Patent Application
20230031778
The invention relates to coating materials, in particular coating materials that provide a gradient of one or more physical or chemical property, that mitigate environmental or operational damage, such as corrosion, to a substrate on which the coating material is applied.
Heat exchangers and other systems of interest, when exposed to the local environment, are subjected to conditions which can affect their performance and ultimately their usefulness. The impacts that can be observed are localized corrosion, water and frost accumulation that increase corrosion, debris accumulation or abrasion by airborne debris, which can reduce the effectiveness of corrosion protections or lead to microbial growth and subsequent corrosion. To further the example, significantly more debris accumulation occurs on the leading edge surfaces of a heat exchanger than on the trailing edge. Water accumulation during condensation can aggregate on the trailing edge of the heat exchanger surface, increasing corrosion damage. Roadway wear occurs in the regions of tire contact and oil accumulation occurs in the center of the lanes, both of which alter the wear and corrosion patterns of the roadway. In order to increase the performance of these devices and systems, it is desirable to directly address these conditions in a targeted manner, at the region of interest.
Coating compositions and methods of use thereof are provided herein.
In one aspect, a composition in the form of a coating or modification on a surface of a substrate is provided, wherein the coating or modification includes a gradient in at least one physical or chemical property across at least a portion of the substrate surface. For example, the at least one physical or chemical property of the gradient may include, but is not limited to, one or more of thickness, density, pore size, pore size distribution, pore filling fraction, chemical or physical composition, oxidation state, metal concentration, crosslinking density, isoelectric point, electrical conductivity, thermal conductivity, and capacitance. In some embodiments a gradient, for example, a gradient of any of the above properties can vary by about 1% to about 99%, about 5% to about 95%, about 10% to about 90%, about 20% to about 80%, or any of about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99%, or any of at least about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99%, relative to the largest value of a given property of the coating or modification or the largest value of a given property on the substrate.
In some embodiments, the coating or modification that includes the gradient in at least one physical or chemical property is in a single layer on the substrate surface. For example, the coating or modification may include a ceramic, a polymeric material, or a self-assembled monolayer.
In some embodiments, the coating or modification includes a plurality of layers, wherein at least one of the layers includes the gradient in at least one physical or chemical property. For example, the at least one layer that includes the gradient may include a ceramic, a polymeric material, or a self-assembled monolayer. In one embodiment, the plurality of layers includes a first layer that includes the gradient in at least one physical or chemical property in contact with the substrate, and a second functional material layer that does not include the gradient over the first layer
In another embodiment, the plurality of layers includes a first layer that does not include the gradient in contact with the substrate and a second functional material layer that includes the gradient over the first layer.
In some embodiments, the coating or modification is applied in a spatially discrete area of the substrate surface, and one or more area of the substrate surface does not include the coating or modification. For example, the coating or modification may be applied in a plurality of spatially discrete areas of the surface of the substrate. In some embodiments, about 1% to about 99%, about 5% to about 95%, about 10% to about 90%, about 20% to about 80%, or any of about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99%, or any of at least about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99% of the substrate surface is covered with the coating, layer(s), or modification.
In some embodiments, the coating or modification is spatially continuous across the entire area or substantially the entire area of the substrate surface.
In some embodiments, the substrate is modified with a conversion coating or primer on the entire substrate surface or substantially the entire substrate surface, and a layer that includes the gradient in at least one physical or chemical property is coated on top of the conversion coating or primer. In one embodiment, the layer that includes the gradient in at least one physical or chemical property is applied in a spatially discrete area of the conversion coating or primer, and one or more area of the conversion coating or primer does not include the layer that includes the gradient. In one embodiment, the layer that includes the gradient in at least one physical or chemical property is applied in a plurality of spatially discrete areas of the conversion coating or primer. In one embodiment, the layer that includes the gradient in at least one physical or chemical property is spatially continuous across the entire area or substantially the entire area of the conversion coating or primer. In some embodiments, the conversion coating or primer includes one or more of a chromate, a fluorozirconate, a fluorotitanate, a sol gel, a phosphate, zirconium, a rare earth metal, and a blue or black oxide. In some embodiments, the layer that includes the gradient in at least one physical or chemical property includes a ceramic, a polymeric material, or a self-assembled monolayer.
In some embodiments, a layer that includes the gradient in at least one physical or chemical property is coated on at least a portion of the substrate surface and a uniform or substantially uniform functional material layer is coated on top of the layer that includes the gradient and across the entire area or substantially the entire area of the substrate surface. In some embodiments, the layer that includes the gradient in at least one physical or chemical property includes a ceramic, a polymeric material, or a self-assembled monolayer.
In some embodiments, the coating or modification or layer that includes the gradient in at least one physical or chemical property comprises or consists of a ceramic material. For example, the ceramic material may be a binderless ceramic material with a crystallinity greater than about 20%. The ceramic material may include a metal oxide, a hydrate of a metal oxide, a metal hydroxide, and/or a hydrate of a metal hydroxide. In some embodiments, the ceramic material includes a metal hydroxide, wherein at least a portion of the metal hydroxide is in the form of layered double hydroxide. In some embodiments, the ceramic material includes one or more property selected from: a surface area of about 10 m2 to 1500 m2 per square meter of projected substrate area; a surface area of about 15 m2 to 1500 m2 per gram of ceramic material; a mean pore diameter of about 2 nm to about 20 nm; a thickness of about 0.2 micrometers to about 25 micrometers; a porosity greater than about 10%; and a void volume of about 100 mm3/g to about 7500 mm3/g as determined by mercury intrusion porosimetry.
In some embodiments, the coating or modification or layer that includes the gradient in at least one physical or chemical property comprises or consists of a latex, a paraffin (an alkane), an alkene, an alcohol, an acrylic, an alkyd, an enamel, an epoxy, a siloxane, a fluoropolymer, or a urethane.
In some embodiments, the coating or modification or layer that includes the gradient in at least one physical or chemical property includes a molecule with a head group and a tail group, for example, wherein the head group includes a silane group, a sulfonate group, a sulfonic acid group, a boronate group, a boronic acid group, a phosphonate group, a phosphonic acid group, a carboxylate group, a carboxylic acid group, a vinyl group, a hydroxide group, an alcohol group, a thiolate group, a thiol group, and/or an quaternary ammonium group, and wherein the tail group includes a hydrocarbon group, a fluorocarbon group, a vinyl group, a phenyl group, an epoxide group, an acrylic group, an acrylate group, a hydroxyl group, a carboxylic acid group, a thiol group, and/or a quaternary ammonium group.
In some embodiments, the substrate surface is a surface of a heat exchanger, a vehicle, an aircraft, a watercraft, or a bridge, or any other surface that is susceptible to environmental wear or degradation under conditions in the environment where it is situated or operated. For example, the substrate surface may be a surface of a brazed aluminum heat exchanger, a copper tube-aluminum fin heat exchanger, or a steel tube-aluminum fin heat exchanger.
In another aspect, a heat exchange or a component thereof is provided, wherein a composition as described herein (i.e., a coating or modification that includes a gradient in at least one physical or chemical property across at least a portion of the substrate surface, as described herein) is applied to a surface of the heat exchanger or the surface of a component of the heat exchanger. For example, the heat exchanger may be a brazed aluminum heat exchanger, a copper tube-aluminum fin heat exchanger, or a steel tube-aluminum fin heat exchanger. The heat exchanger surface or component may exhibit greater resistance to environmental damage than an identical heat exchanger or component that does not include the composition described herein.
In another aspect, a method is provided for protecting a substrate from environmental damage. The method includes applying a composition as described herein (i.e., a coating or modification that includes a gradient in at least one physical or chemical property across at least a portion of the substrate surface) to a substrate, wherein the substrate exhibits greater resistance to environmental damage than an identical substrate that does not include the composition. For example, the environmental damage may include, but is not limited to, one or more of corrosion, debris accumulation, water or ice accumulation, biofouling, and abrasion. In one embodiment, corrosion due to water or ice accumulation is reduced or prevented, in comparison to an identical substrate that does not include the composition as described herein.
Selective application of coating compositions can be used to provide protection against environmental damage. Furthermore, over time, the conditions to be prevented or treated change. This can be addressed through a layered coating structure which provides different protections as the layers are altered, for example, through the lifetime of a device.
Provided herein are coating compositions and substrate modifications to minimize environmental wear or degradation, such as corrosion, in areas where environmental exposure and damage is especially challenging, such as on edges, material or composite interfaces, regions of low velocity, regions of high electrochemical corrosion potential, or regions that are exposed to or susceptible to excess moisture, salt, debris accumulation, biofouling, or abrasion.
Coating materials or surface modification may be used to apply more corrosion resistant materials or to promote or enhance movement of a liquid, such as water, away from a substrate, in areas of high environmental exposure or stress, or stress due to operational factors during usage of a device, to partially coat a component in instances where coating of an entire surface or device is not needed, to protect materials differently over time, e.g., through differences in thickness of coating material or surface modification across a substrate surface or through a surface normal gradient (for example, a gradient of one or more chemical or physical property from the top of the coating material or surface modification to the bottom which is in contact with the substrate surface) and/or as a branding or cost cutting measure.
Selective application of coating materials or surface modifications can also be used to achieve complementary benefit such as corrosion resistance, while minimizing potential negative impacts such as heat transfer losses due to thermal resistance of the coating.
One application of use involves heat exchangers. Some outdoor heat exchangers corrode and fail at very specific locations due to standing water after a rain, sprinklers, proximity to or use in marine environments, or animal, e.g., cat, urination. Other environmental stresses that may be mitigated or eliminated by application of the compositions and surface modifications described herein include exhaust pollution, urban pollution, dust/debris, fertilizer, road salt, sand, marine aerosols, industrial emissions (e.g., refinery, water treatment, manufacturing), or microbial (e.g., bacterial, fungal) or viral exposure and/or degradation, including biofilm formation (i.e., anti-microbial, anti-bacterial, anti-fungal, or anti-viral coating or surface modification). Spatial gradients of properties can be used to create a gradient effect. For example, a spatial gradient of porosity that directionally wicks a fluid such as water and “pumps” it from one direction to another may be used for anti-corrosion and other purposes, such as enhanced drying or fluid transfer.
In some embodiments, the coating or surface modification may render a heat exchanger or component thereof resistant to impinging pollutants (e.g., slaughterhouse particles, corrosive aerosols, etc.) and increase thermal resistance to decrease frosting rate, by reducing thermal conductivity and thereby increasing surface temperature. Downstream in the fin pack, the coating may be different to reduce corrosion resistance rate and improve heat transfer/frost suppression properties.
A coating or surface modification may be applied to an entire substrate surface or selectively (to one or more portion of a substrate surface, such as to one or more area that is exposed to adverse environmental conditions or subject to environmental or operational stress). In certain embodiments described herein, coating or surface modifications are configured as a gradient (i.e., spatial variability) in one or more dimension, across a substrate surface or across a device or a portion or component of a device. Exemplar material parameters may include gradients in material density, pore size distribution, pore filling (i.e., filling fraction, or spatial gradient of materials filling pores of a porous material), or material thickness.
Methods of mitigating or preventing environmental or operational damage to a substrate or a device or component into which the substrate is incorporated are provided. The methods include spatially continuous or discrete application of any of the coating or surface modification materials described herein to a substrate, including one or more material that includes a gradient in at least one chemical or physical property, wherein the substrate is resistant to environmental or operational damage, such as, but not limited to, corrosion, debris accumulation, water or ice accumulation, biofouling, or abrasion, in comparison to a substrate that does not include the coating or substrate modification.
Numeric ranges provided herein are inclusive of the numbers defining the range.
“A,” “an” and “the” include plural references unless the context clearly dictates otherwise.
The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.”
“Binder” or binding agent is any material or substance that holds or draws other materials together to form a cohesive whole mechanically, chemically, by adhesion or cohesion.
“Binderless” refers to absence of a binder that may be exogenously added to a primary material to improve structural integrity, particularly with regard to an organic binder or resin (e.g., polymers, glues, adhesives, asphalt) or inorganic binder (e.g., lime, cement glass, gypsum, etc.).
“Capillary climb” refers to a surface tension driven flow of liquid up a sample (the capillary climb is parallel to, and opposite to, the direction of the force (vector) due to gravity) upon contact with a free surface of liquid as a result of the porous substrate.
A “ceramic” or “ceramic material” refers to a solid material including an inorganic compound of a metal or a metalloid, and a non-metal, with ionic or covalent bonds. A “non-metal” may include oxygen (oxide ceramic), or carbon (carbide) or nitrogen (nitride) (non-oxide ceramics). A “metal” may include a non-hydrogen element of Group 1 of the periodic table, an element of Groups 2-12 of the periodic table, or an element from the p-block (Groups 12-17 of the periodic table), e.g., Al, Ga, In, Tl, Sn, Pb, Bi, or combinations thereof. A “metalloid” may include B, Si, Ge, As, Sb, Se, Te, or Po, or combinations thereof.
“Contact angle” refers to the angle measured through a liquid between a surface and the liquid-vapor interface at the contacting surface.
“Contiguous” or “contiguity” refers to pores and structures that contain walls and features in direct contact with one another or that share a common wall across a region or dimension large relative to an individual pore or structure.
A “conversion coating” refers to a surface layer in which reactants are chemically reacted with the surface to be treated, which converts the substrate into a different compound. This process is typically not additive or a deposition, but may result in a small mass change.
“First quartile pore diameter” refers to the value of the pore diameter at which the cumulative pore surface area determined in the direction of increasing pore size is equivalent to 25% of the total cumulative pore surface area as determined by BJH gas adsorption/desorption measurements.
A “functional material layer” refers to a layer of material which may serve as the uppermost surface layer interacting with the surrounding environment or may serve as an interfacial layer for subsequent materials (intermediate layer between two other layers of material). A functional material layer imparts one or more desirable functional properties to the underlying substrate and/or the material on which it is deposited.
A “gradient” refers herein to a quantitative increase or decrease in one or more physical or chemical property of a material observed by passing spatially from one point to another point along a substrate surface on which the material is situated or immobilized, and varying in an x, y, or z direction in Cartesian coordinates on or through the material. Nonlimiting examples of gradient properties include thickness, density, hardness, ductility, pore size, pore size distribution, pore filling fraction, or chemical or physical composition, including but not limited to, oxidation state, metal concentration, or crosslinking density, for example, resulting in variation in isoelectric point, electrical conductivity, thermal conductivity, capacitance, etc.
“Hydrophilic” refers to a surface that has a high affinity for water. Contact angles can be very low (e.g. less than 30 degrees as measured from the surface through the liquid water in the presence of air) and/or immeasurable.
“Layered double hydroxide” refers a class of ionic solids characterized by a layered structure with the generic sequence [AcB Z AcB]n, where c represents layers of metal cations, A and B are layers of hydroxide anions, and Z are layers of other anions and/or neutral molecules (such as water). Layered double hydroxides are also described in PCT Application No. PCT/US2017/052120, which is incorporated by reference herein in its entirety.
A “macro void” refers to a geometric space within solid that has a characteristic dimension substantially larger than the characteristic dimension of an individual pore or feature (e.g., thickness), for example, at least about 5× to about 10× or about 10× to about 100× greater than the characteristic dimension.
“Mean” refers to the arithmetic mean or average.
“Mean pore diameter” is calculated using total surface area and total volume measurements from the Barrett-Joyner-Halenda (BJH) adsorption/desorption method as 4 times the total pore volume divided by the total surface area (4V/A), assuming a cylindrical pore.
“Multimodal” refers to a distribution which contains more than one different mode that appears as more than one distinct peak.
“Permeability” in fluid mechanics is a measure of the ability of a porous material to allow fluids to pass through it. The permeability of a medium is related to the porosity, but also to the shapes of the pores in the medium and their level of connectedness.
“Pore size distribution” refers to the relative abundance of each pore diameter or range or pore diameters as determined by mercury intrusion porosimetry (MIP) and Washburn's equation.
“Porosity” is a measure of the void (i.e., “empty”) spaces in a material, and is a fraction of the volume of voids, i.e., macro voids. over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Porosities disclosed herein were measured by mercury intrusion porosimetry.
“Porous” refers to spaces, holes, or voids within a solid material.
“Superhydrophobic” refers to a surface that is extremely difficult to wet. The contact angle of a water droplet on a superhydrophobic material here a superhydrophobic surface refers to a sessile drop contact angles >150°. Highly hydrophobic contact angles are >120°. Contact angles noted here are angles formed between the surface through the liquid.
“Surface area per square meter of projected substrate area” refers to the actual measured surface area, usually measured in square meters, divided to the surface area of the substrate if it were atomically smooth (no surface roughness), also typically in square meters.
“Synergy” or “synergistic” refers to the interaction or cooperation between two or more substances, materials, or agents to produce a combined effect that is greater (positive synergy) or lesser (negative synergy) than the sum of their separate, individual effects.
“Thickness” refers to the length between the surface of the substrate and the top of the surface modification (e.g., ceramic) material.
“Third quartile pore diameter” refers to the value of the pore diameter at which the cumulative pore surface area determined in the direction of increasing pore size is equivalent to 75% of the total cumulative pore surface area as determined by BJH gas adsorption/desorption measurements.
“Tortuosity” refers to the fraction of the shortest pathway through a porous structure Δl and the Euclidean distance between the starting and end point of that pathway Δx.
“Tunable” refers to the ability of a function, characteristic, or quality of a material to be changed or modified.
The selective coating of a substrate, such as a surface of a heat exchanger, can be performed in multiple ways, such as: partial (selective) coating on a portion of the surface of a substrate, where some locations are uncoated and some are coated, based on local corrosion resistance need or other needs, such as, but not limited to, limiting microbial growth in regions of high moisture (e.g., Legionella) or movement of a liquid, such as water, away from the substrate; complete coating of a substrate with first material A and partial coating of a second material B over the first material (i.e., selective coating of second material B over a portion (one or more areas) of the surface of first material A), where the second material may be the same as or different from the first material; and a gradient within a coating across the substrate based on need for protection from environmental or operational stress conditions.
Gradients herein are spatially variable with respect to at least one chemical or physical property. For example, a coating or surface modification material A may be a uniform material on a substrate surface or may include a spatial gradient (variability) in one or more property such as, but not limited to, material density, pore size distribution, pore filling fraction, or thickness. Additionally, an optional second material B may also be applied over material A, which may be a uniform material or may possess spatial variability in one or more property, such as, but not limited to, material density, pore size distribution, thickness, and/or filling fraction of the pores of material A. In some embodiments, an optional third material C may also be selectively applied and may be a uniform material across the substrate or across the material directly below or may possess spatial variability in one or more property, such as, but not limited to, material density, pore size distribution, thickness, and/or filling fraction of the pores of material B. In some embodiments, material C is applied over a stack of materials, such as, but not limited to, A-B-A, and may possess spatial variability in one or more property, such as, but not limited to, material density, pore size distribution, thickness, and/or filling fraction of the pores of the material directly below material C, e.g., material A. Additional optional layers of uniform or gradient materials may also be included. The coating or surface modification material(s) may be applied continuously across the substrate surface or in one or more discrete (selective) areas, such as areas of the substrate that are subject to environmental or operational stress in an application of use for a device or component into which the substrate is incorporated.
A gradient layer as disclosed herein may include a gradient of one or more property of a structural layer. For example, a gradient may include higher porosity near a joint, a change in structural composite thickness on a panel, e.g., thicker near the bottom or edges from the draining and dryout of an immersion process at a specific temperature, selectively spraying materials in select regions, adding additional coats of materials in select regions, configuration of spray application resulting in a greater addition of material at the leading edge, or a composition change impacting electrochemical potential.
A gradient may be developed during processing of a structural layer, for example, by changing concentration levels of reactants or components of the composition (dropping) during processing, which results in changes in the composition through the thickness of the coating, and/or changing temperature, e.g., temperature of the processing bath, during processing to change structure or to change part temperature during processing, or having variable temperature zones during processing, such as a hot zone and a cold zone of the part to result in thicker, thinner, or different materials, e.g., structured ceramic materials. Modification of the local chemical reactivity through mechanical part agitation, fluid advection, addition of localized heat or light, pressure differences and/or gravitational settling differences can also be used to generate gradient properties. The drying and curing process can also be used to generate property gradients through the use of select temperature zones, drying orientations, and/or selective light addition.
In some embodiments, one or more coating or surface modification material (e.g., materials A-C) is a structured ceramic, such as a binderless ceramic surface modification material, for example, with pores that may be filled, unfilled, or partially filled, optionally in a manner that produces a gradient with respect to partial filling of the pores with a second material. In one embodiment, the ceramic material includes a contiguous network of pores filled with a second material, such as a polymer material.
In some embodiments, a surface modification material may be a conversion coating or primer (for example, but not limited to, trivalent chromium phosphate, other chromates, fluorozirconates, fluorotitanates, sol gels, phosphates, blueing or black oxide coatings or anodizing).
In some embodiments, one or more surface modification material is applied to a paint primer. For example, a deposited material may be a paint, such as a latex, acrylic, alkane, alkene, alcohol, enamel, epoxy, siloxane, polysilazane, fluoropolymer, or urethane. For example, a deposited material may be a natural or processed fatty acid, alcohol, hydrocarbon, or oil, such as linoleic, palmitic, oleic acid, glycerol, paraffin, turpentine, tall oil, linseed oil, palm oil, tung oil or boiled linseed oil, hydrogenated fatty acids, refined glycerol, distilled paraffin, mineral oil, or refined palm oil.
In some embodiments, one or more surface modification material is a monolayer chemistry, which may provide any of an array of properties, such as, but not limited to, wettability, sealant, optical, etc.
Many substrates have multimetal components, such as copper-aluminum heat exchangers, steel-aluminum heat exchangers, brazed aluminum heat exchangers, screws and rivets in bridges and vehicles, and other components that contain composite interfaces. Selective protection in these composite scenarios can provide additional protection for galvanic corrosion susceptible metal couples (e.g. selective anode protection) for a wide variety of environments and anodic/cathodic areas. Other substrates, homogenous or heterogenous in composition, contain local areas susceptible to corrosion due to local environments such as local abrasion, standing liquids, or air flow gradients.
In some embodiments, the substrate is a heat exchanger or component thereof, such as a microchannel heat exchanger. Other embodiments include bridges, aircraft, vehicles, and watercraft, or components thereof.
Nonlimiting examples of properties and compositions of a coating or surface modification include a layer (“n”), as described herein:
n1 Conversion coating or primer—continuous coverage without gradient
n2 Conversion coating or primer—continuous coverage with gradient
n3 Conversion coating or primer—selective (discrete) coverage without gradient
n4 Conversion coating or primer—selective coverage with gradient
n5 Structured ceramic—continuous coverage without gradient
n6 Structured ceramic—continuous coverage with gradient
n7 Structured ceramic—selective coverage without gradient
n8 Structured ceramic—selective coverage with gradient
n9 Deposited monolayer/paint/oil/resin—continuous coverage without gradient
n10 Deposited monolayer/paint/oil/resin—continuous coverage with gradient
n11 Deposited monolayer/paint/oil/resin—selective coverage without gradient
n12 Deposited monolayer/paint/oil/resin—selective coverage with gradient
Nonlimiting permutations of coatings or surface modifications (n=“A”, “B”, “C”, . . . , where A, B, C, etc. are listed in order of application or proximity to the substrate, for example, wherein A is a material in contact with or proximal to the substrate or the bottommost material in a plurality of layers of material), include:
A1-B11 (continuous coverage conversion coating+selective coverage paint)
A1-B10 (continuous coverage conversion coating+continuous coverage gradient paint)
A1-B12 (continuous coverage conversion coating+selective coverage gradient paint)
A1-B6 (continuous coverage primer+continuous coverage gradient structured ceramic)
A1-B7 (continuous coverage primer+selective coverage structured ceramic)
A1-B8 (continuous coverage primer+selective coverage gradient structured ceramic)
A1-B5-C9-D11 (continuous coverage conversion coating+continuous coverage structured ceramic+continuous coverage functional material layer+selective coverage paint)
A1-B5-C10 (continuous coverage conversion coating+continuous coverage structured ceramic+continuous coverage gradient functional material layer)
A1-B5-C11 (continuous coverage conversion coating+continuous coverage structured ceramic+selective functional material layer)
A1-B5-C12 (continuous coverage conversion coating+continuous coverage structured ceramic+selective coverage gradient functional material layer)
A3 (selective coverage conversion coatings)
A5-B9-C11 (continuous coverage structured ceramic+continuous coverage functional material layer+coverage selective paint)
A5-B10 (continuous coverage structured ceramic+continuous coverage gradient functional material layer)
A5-B11 (continuous coverage structured ceramic+selective coverage functional material layer)
A5-B12 (continuous coverage structured ceramic+selective coverage gradient functional material layer)
A6 (continuous coverage gradient structured ceramic)
A6-B9 (continuous coverage gradient structured ceramic+continuous coverage functional material layer)
A6-B10 (continuous coverage gradient structured ceramic+continuous coverage gradient functional material layer)
A6-B11 (continuous coverage gradient structured ceramic+selective coverage functional material layer)
A6-B12 (continuous coverage gradient structured ceramic+selective coverage gradient functional material layer)
A7 (selective coverage structured ceramic)
A7-B9 (selective coverage structured ceramic+continuous coverage functional material layer)
A7-B11 (selective coverage structured ceramic+selective coverage functional material layer)
A8 (selective coverage gradient structured ceramic)
A9-B11 (continuous coverage monolayer coating+selective coverage paint)
A10 (continuous coverage gradient paint)
A11 (selective coverage paint)
A12 (selective coverage gradient paint)
A continuous or discrete coating or surface modification material as described herein may be a structured ceramic, for example, a binderless (e.g., surface immobilized) ceramic, such as a binderless ceramic with a crystallinity greater than about 20%. In some embodiments, the structured ceramic is porous. Nonlimiting examples of ceramic materials are provided in PCT/US19/65978, which is incorporated herein by reference in its entirety.
The ceramic material may include a metal oxide and/or hydroxide ceramic, for example, a single metal or mixed metal oxide and/or hydroxide ceramic. In some embodiments, the ceramic material includes a metal hydroxide and/or hydroxide ceramic, for example, a single metal or mixed metal oxide and/or hydroxide ceramic. In some embodiments, the ceramic material includes a metal oxide and a metal hydroxide ceramic, wherein the metal oxide and the metal hydroxide include the same or different single metal or mixed metal. In some embodiments, the ceramic material includes a metal oxide and/or a metal hydroxide ceramic, wherein the substrate is hydrated by water or other compounds resulting in a change of surface energy and potentially the ratio of metal oxide to metal hydroxide composition of the ceramic. In some embodiments, the ceramic material includes a metal hydroxide, wherein at least a portion of the metal hydroxide is in the form of a layered double hydroxide, e.g., at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of the metal hydroxide is layered double hydroxide.
In some embodiments, a “metal oxide” or “metal hydroxide” may be in the form of a hydrate of a metal oxide or metal hydroxide, respectively, or a portion of the metal oxide or metal hydroxide may be in the form of a hydrate of a metal oxide or metal hydroxide, respectively.
A mixed metal oxide or mixed metal hydroxide may include, for example, oxides or hydroxides, respectively, of more than one metal, such as, but not limited to, iron, cobalt, nickel, copper, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tantalum, zinc, lead, tin, tungsten, cerium, praseodymium, samarium, gadolinium, lanthanum, magnesium, aluminum, or calcium.
In some embodiments, the ceramic material is a binderless ceramic material, i.e., deposited onto a substrate without a binder. In some embodiments, the ceramic materials immobilized on the substrate.
In some embodiments, the ceramic material has an open cell porous structure, for example, characterized by one or more of: ability to effect capillary rise of a liquid having a low surface tension (e.g., less than about 25 mN/m, such as isopropanol) at greater than about 5 mm up a surface against gravity in a closed container in 1 hour; surface area of about 0.1 m2/g to about 10,000 m2/g; mean pore size of about 10 nm to about 1000 nm or about 1 nm to about 1000 nm; pore volume as measured by mercury (Hg) intrusion porosimetry of about 0 to about 1 cc/g; and tortuosity of about 1 to about 1000 as defined by the length of a fluid path to the shortest distance, the “arc-chord ratio”; and/or permeability of about 1 to about 10,000 millidarcy.
In some embodiments, the ceramic material is porous, with a porosity of about 5% to about 95%. In some embodiments, the porosity may be any of at least about or greater than about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. In some embodiments, the porosity is about 10% to about 90%, about 30% to about 90%, about 40% to about 80%, or about 50% to about 70%.
In some embodiments, the porous ceramic material has a permeability of about 1 to 10,000 millidarcy. In some embodiments, the permeability may be any of at least about 1, 10, 100, 500, 1000, 5000, or 10,000 millidarcy. In some embodiments, the permeability is about 1 to about 100, about 50 to about 250, about 100 to about 500, about 250 to about 750, about 500 to about 1000, about 750 to about 2000, about 1000 to about 2500, about 2000 to about 5000, about 3000 to about 7500, about 5000 to about 10,000, about 1 to about 1000, about 1000 to about 5000, or about 5000 to about 10,000 millidarcy.
In some embodiments, the porous ceramic material includes a void volume of about 100 mm3/g to about 7500 mm3/g, as determined by mercury intrusion porosimetry. In some embodiments, the void volume is any of at least about 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, or 7500 mm3/g. In some embodiments, the void volume is any of about 100 to about 500, about 200 to about 1000, about 400 to about 800, about 500 to about 1000, about 800 to about 1500, about 1000 to about 2000, about 1500 to about 3000, about 2000 to about 5000, about 3000 to about 7500, about 250 to about 5000, about 350 to about 4000, about 400 to about 3000, about 250 to about 1000, about 250 to about 2500, about 2500 to about 5000, or about 500 to about 4000 mm3/g.
A porous ceramic material as disclosed herein may be characterized by its interaction with liquid materials. As previously noted, the ceramic material may be characterized the ability to effect capillary rise of a liquid having a low surface tension (e.g., less than about 25 mN/m, such as isopropanol) at greater than about 5 mm up a surface against gravity in a closed container in 1 hour. Other solvents with surface tension less than about 25 mN/m at 20° C. of may be used including, but not limited to, Perfluorohexane, Perfluoroheptane, Perfluorooctane, n-Hexane (HEX), Polydimethyl siloxane (Baysilone M5), tert-Butylchloride, n-Heptane, n-Octane (OCT), Isobutylchloride, Ethanol, Methanol, Isopropanol, 1-Chlorobutane, Isoamylchloride, Propanol, n-Decane (DEC), Ethylbromide, Methyl ethyl ketone (MEK), n-Undecane, Cyclohexane. Other solvents with surface tension at 20° C. of >25 mN/m may be used including: Acetone (2-Propanone), n-Dodecane (DDEC), Isovaleronitrile, Tetrahydrofuran (THF), Dichloromethane, n-Tetradecane (TDEC), sym-Tetrachloromethane, n-Hexadecane (HDEC), Chloroform, 1-Octanol, Butyronitrile, p-Cymene, Isopropylbenzene, Toluene, Dipropylene glycol monomethylether, 1-Decanol, Ethylene glycol monoethyl ether (Ethyl Cellosolve), 1,3,5-Trimethylbenzene (Mesitylene), Benzene, m-Xylene, n-Propylbenzene, Ethylbenzene, n-Butylbenzene, 1-nitro propane, o-Xylene, Dodecyl benzene, Fumaric acid diethylester, Decalin, Nitroethane, Carbon disulfide, Cyclopentanol, 1,4-Dioxane, 1,2-Dichloro ethane, Chloro benzene, Dipropylene glycol, Cyclohexanol, Hexachlorobutadiene, Bromobenzene, Pyrrol (PY), N,N-dimethyl acetamide (DMA), Nitromethane, Phthalic acid diethylester, N,N-dimethyl formamide (DMF), Pyridine, Methyl naphthalene, Benzylalcohol, Anthranilic acid ethylester, Iodobenzene, N-methyl-2-pyrrolidone, Tricresylphosphate (TCP), m-Nitrotoluene, Bromoform, o-Nitrotoluene, Phenylisothiocyanate, a-Chloronaphthalene, Furfural (2-Furaldehyde), Quinoline, 1,5-Pentanediol, Aniline(AN), Polyethylene glycol 200 (PEG), Anthranilic acid methylester, Nitrobenzene, a-Bromonaphthalene (BN), Diethylene glycol (DEG), 1,2,3-Tribromo propane, Benzylbenzoate (BNBZ), 1,3-Diiodopropane, 3-Pyridylcarbinol (PYC), Ethylene glycol (EG), 2-Aminoethanol, sym-Tetrabromoethane, Diiodomethane (DI), Thiodiglycol (2,2′-Thiobisethanol) (TDG), Formamide (FA), Glycerol (GLY), Water (WA), and Mercury
The porous ceramic surface modification material may possess the ability to effect capillary rise of water, at various temperatures. These materials may have the ability to separate miscible materials and binary azeotropes, such as ethanol-water, ethyl acetate-ethanol, or butanol-water, to break ternary azeotropes, or to remove amyl alcohol from mixtures including ethanol and water.
The pores of the porous ceramic surface modification material may include open cells filled with one or more gas, may include partially filled cells (e.g., partially filled with one or more solid material(s)), or may include completely or substantially filled cells (e.g., completely or substantially filled with one or more liquid and/or solid material(s)). In some embodiments, the pores are partially, substantially, or completely filled with a gas, liquid, or solid substance, or combinations thereof.
In some embodiments, the pores are partially filled with a first material and then partially or completely filled with a second material. In some embodiments, the second material is added as a layer of material over partially filled pores. In some embodiments, the first material is a gas, solid, or liquid, or combination of gas, liquid, and/or solid substance(s). In some embodiments, the second material is a gas, solid, and/or liquid substance(s), or the environment (e.g., air). Examples include, and functions thereby imparted include changes in the porosity, wicking, repellency and/or wetting behavior; changes in the composite (comprising the porous material and second material) to modify electrical/dielectric properties, to modify mechanical properties such as abrasion resistance, hardness, toughness, tactile feel, elastic modulus, yield strength, yield stress, Young's modulus, surface (compressive or tensile) stress, and/or elasticity; changes in thermal properties such as thermal diffusivity, conductivity, thermal expansion coefficient, thermal interface stress, and/or thermal anisotropy; modification of optical properties such as emissivity, color, reflectivity, and/or absorption coefficients; modification of chemical properties such as corrosion, catalysis, reactivity, inertness, compatibility, fouling resistance, ion pump blocking, microbial resistance, and/or microbial compatibility; and/or as a substrate for biocatalysis.
In some embodiments, the first material interacts with the second material in a positive or negative synergistic manner to alter one or more functional characteristic of the ceramic material, such as, but not limited to, wettability, hardness, elasticity, a mechanical, electrical, piezoelectric, optical, adhesion, or thermal property, microbial affinity or resistance, alteration of biofilm growth, catalytic activity, permeability, aesthetic appearance, liquid repellency, and/or corrosion resistance.
Nonlimiting materials that may be used to partially or completely fill pores include molecules capable of binding to the surface such as molecules with a head group and a tail group wherein the head group is a silane, phosphonate or phosphonic acid, a carboxylic acid, vinyl, a hydroxide, a thiol, or ammonium compound. The tail group can include any functional group such as hydrocarbons, fluorocarbons, vinyl groups, phenyl groups, and/or quaternary ammonium groups. Other ceramic materials can also be deposited into the pores partially or completely. Polymers may also be deposited into the pores partially or completely. Ceramic materials may include, for example, one or more oxide of zinc, aluminum, manganese, magnesium, cerium, gadolinium, and cobalt. In addition, ceramic materials may include any solid material which can be added to the surface modification material, including an inorganic compound of metal, non-metal, or metalloid atoms primarily held in ionic and covalent bonds, such as, for example, clays, silicas, and glasses. Polymers may include, for example, natural polymeric materials such as hemp, shellac, amber, wool, silk, natural rubber, cellulose, and other natural fibers, sugars, hemi- and holo-celluloses, polysaccharides, and biologically derived materials such as extracellular proteins, DNA, chitin. Synthetic polymers include, for example, polymers and co-polymers containing polyethylene, polypropylene polystyrene, polyvinyl chloride, synthetic rubber, phenol formaldehyde resin (or Bakelite), neoprene, nylon, polyacrylonitrile. PVB, silicone, polyisobutylene. PEEK, PMMA, and PTFE.
In some embodiments, the pores are filled partially with a thin composite polymer layer to produce a surface modification material that has porosity and functionality provided by the polymer. In other embodiments, the pores are filled completely with a thick polymer layer to produce a surface modification material with a thick polymer layer that has composite properties of the porous base material and the polymer layer. A polymer as described in the compositions herein includes co-polymers.
In some embodiments, the pores are partially or completely filled with a layer of material deposited over the surface of the surface modification material. In some embodiments, a layer of material is deposited that adds one or more functional group(s) to the surface modification material, such as, but not limited to, ammonium groups (e.g., quaternary ammonium groups), alkyl groups, perfluoroalkyl groups, fluoroalkyl groups. In some embodiments, a polymer or ceramic layer is deposited. In one embodiment, a ceramic top surface layer is deposited which is the same or different ceramic than the ceramic of the binderless porous ceramic material on the substrate. Examples of functional group(s) and functions thereby imparted include quaternary ammonium groups for anti-microbial functions, alkyl chains for water repellency and hydrocarbon affinity, perfluoroalkyl groups for water and oil repellant functions, polymers for mechanical property function, other ceramics for aesthetic functions, optoelectronic functions, or anti-corrosive functions.
In some embodiments, the pores are partially or completely filled with a gas, liquid, or solid substance, or combinations thereof, and the composition further includes a layer of a top surface material over the ceramic material, and the top surface material imparts one or more functionality, such as, but not limited to, wettability with a liquid and/or selective separation of compounds in a liquid. In certain embodiments, the top surface material is a separate material from the substance with which the pores are partially, substantially, or completely filled, and does not itself fill or intrude into the pores. In some embodiments, the top surface material interacts with the substance(s) in the pores. For example, the top surface material may interact with the substance(s) in the pores to provide one or more functionality, such as, but not limited to, thermal management, electrochemical reactivity modulation, and/or mechanical property modulation. In certain embodiments, the top surface material is the surrounding environment with which the binderless porous ceramic material is in contact.
In some embodiments, the pores are substantially or completely filled with a polymer or with a ceramic material.
In some embodiments, a material in the pores interacts with the ceramic material. Examples of such materials and functions thereby imparted include the oxidation of the surface modification material by ambient liquid or vapor, the condensation of minor components (e.g., environmental pollutants), the capture or oxidation of hazardous environmental materials such as CO or H2S from environmental air, and/or the collection and retention of materials in the environment.
In some embodiments, moisture in the environment or added to the pores interacts with a material in the pores to modify the material in the pores or the surface modification material. Examples of such materials and functions thereby imparted include changes in wetting behavior, in optical properties, changes in oxidation state or reactivity, changes in the rate of evaporation, frosting, icing, or condensation.
In some embodiments, material in the pores may be designed to interact with the ceramic material to “tune” the properties of the overall surface. Examples of tunable properties includes, but are not limited to, wettability, hardness, microbial resistance, catalytic activity, corrosion resistance, color, and/or photochemical activity.
In some embodiments, the ceramic surface modification material and a material in the pores interact in a synergistic manner, for example, enhancing or reducing at least one functionality of the surface modification material and/or the material in the pores, in comparison to the functionality of the surface modification material and/or the material in the pores alone. In some embodiments, two or more materials in the pores interact in a synergistic manner, for example, enhancing or reducing at least one functionality of at least one material in the pores, in comparison to the functionality of that material alone.
In some embodiments, the ceramic surface modification material is asymmetric, for example, a pore morphology that is not spherical, cylindrical, cubic or otherwise ordered as having a well-defined, relatively constant, normal distribution of surface area to volume, as characterized a by a ratio of the pore diameter at the first quartile to the pore size at the third quartile as a function of the thickness of the binderless ceramic surface modification. In particular, the pore morphology is asymmetric about its center when compared to a spherical, cylindrical, or cubic structure. A nonlimiting example of asymmetric pores is depicted in PCT Application No. PCT/US19/39743, which is incorporated by reference herein in its entirety.
A porous ceramic surface modification material may be characterized by a broad pore size distribution that varies with distance from the substrate. In particular, the pore structure at a given distance from the substrate can be characterized locally, e.g., as described herein and has a different characterization at a different distance. The resulting asymmetry is determined in situ by the combination of substrate, ionic mobility, processing conditions such as temperature, pressure, and concentrations. The degree of asymmetry can be further modified through bulk means such as mixing, agitation, electric field modulation, and tank filtration, or through surface directed process means such as shear rates, impinging flows or surface charge modification and modulation. The asymmetry can be determined ex situ through a variety of means such as etching, track etching, ion beam milling, oxidation, photocatalysis, or through additional means. These approaches are to refer to materials which have a narrower, or symmetric pore structures, with thickness and/or pore depth, such as zeolites, track etched membranes, or expanded PTFE membranes.
In some embodiments, the porous ceramic surface modification material includes mesoporous mean pore sizes that range from about 2 nm to about 50 nm. In other embodiments, the mean pore sizes range from about 50 nm to about 1000 nm. In some embodiments, the binderless porous ceramic material includes a mean pore diameter of about 2 nm to about 20 nm. In some embodiments, the mean pore diameter is any of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nm. In some embodiments, the mean pore diameter is any of about 2 to about 5, about 4 to about 9, about 5 to about 10, about 7 to about 12, about 9 to about 15, about 12 to about 18, about 15 to about 20, about 4 to about 11, about 5 to about 9, about 4 to about 8, or about 7 to about 11 nm.
The ceramic surface modification material may include one or more metal oxide and/or metal hydroxide (and/or hydrates thereof). Non-limiting examples of metals that may be included in the ceramic compositions disclosed herein include: zinc, aluminum, manganese, magnesium, cerium, copper, gadolinium, tungsten, tin, lead, and cobalt. In some embodiments, the ceramic material includes a transition metal, a Group II element, a rare-earth element (e.g., lanthanum, cerium gadolinium, praseodymium, scandium, yttrium, samarium, or neodymium), aluminum, tin, or lead. In some embodiments, the ceramic material includes two or more metal oxides (e.g., a mixed metal oxide) including but not limited to zinc, aluminum, manganese, magnesium, cerium, praseodymium, and cobalt.
In some embodiments, the ceramic surface modification material includes: a mixture of zinc and aluminum oxides and/or hydroxides; a mixture of ZnO and Al2O3, and Zn-aluminates; mixtures of materials comprising any/all phases comprising Zn, Al, and oxygen; a mixture of manganese and magnesium oxides and/or hydroxides; manganese oxide; aluminum oxide; a mixed metal manganese oxide and/or hydroxide; a mixture of magnesium and aluminum oxides and/or hydroxides; a mixture of magnesium, cerium, and aluminum oxides and/or hydroxides; a mixture of zinc, gadolinium, and aluminum oxides and/or hydroxides; a mixture of cobalt and aluminum oxides and/or hydroxides; a mixture of manganese and aluminum oxides and/or hydroxides; a mixture of cerium and aluminum oxides and/or hydroxides; a mixture of iron and aluminum oxides and/or hydroxides; a mixture of tungsten and aluminum oxides and/or hydroxides; a mixture of tin and aluminum oxides; tungsten oxide and/or hydroxide; magnesium oxide and/or hydroxide; manganese oxide and/or hydroxide; tin oxide and/or hydroxide; or zinc oxide and/or hydroxide.
In some embodiments, at least one metal in the ceramic material is in the 2+ oxidation state.
In some embodiments, the ceramic surface modification material includes one or more oxide and/or hydroxide of zinc, aluminum, manganese, magnesium, cerium, gadolinium, and cobalt, and the substrate is aluminum or an aluminum alloy.
In some embodiments, the ceramic surface modification material is superhydrophobic. In some embodiments, the surface modification material is highly hydrophobic. In some embodiments, the surface modification material includes one or more functional characteristic selected from wettability, hardness, elasticity, mechanical, electrical, piezoelectric, electromagnetic, optical, adhesion, or thermal properties, microbial affinity or resistance, alteration of biofilm growth, catalytic activity, permeability, aesthetic appearance, and corrosion resistance, in comparison to a substrate that does not include the ceramic material.
In some embodiments, a functional material layer (e.g., top layer of material) is deposited onto the ceramic material. Examples of such materials include, but are not limited to, quaternary ammonium groups for anti-microbial functions, alkyl chains for water repellency and hydrocarbon affinity, perfluoroalkyl groups for water and oil repellant functions, polymers for mechanical property function, other ceramics for aesthetic functions, optoelectronic functions, or anti-corrosive functions. Examples of functionalities imparted by such materials include, but are not limited to,—changes in the porosity, wicking, repellency, and/or wetting behavior; changes in the composite (including the porous material and second material) to modify electrical/dielectric properties, to modify mechanical properties such as abrasion resistance, hardness, toughness, tactile feel, elastic modulus, yield strength, yield stress, Young's modulus, surface (compressive or tensile) stress, tensile strength, compression strength, and/or elasticity; thermal properties such as thermal diffusivity, conductivity, thermal expansion coefficient, thermal interface stress, thermal anisotropy, to modify optical properties such as emissivity, color, reflectivity, and/or absorption coefficients, to modify of chemical properties such as corrosion, catalysis, reactivity, inertness, compatibility, fouling resistance, ion pump blocking, microbial resistance and/or microbial compatibility, promotion of adhesion of subsequent material layers, and/or as a substrate for biocatalysis.
In some embodiments, the ceramic surface modification material is resistant to degradation by ultraviolet radiation, in comparison to the substrate material, such as a polymer or any of the substrate materials disclosed herein.
In some embodiments, the ceramic surface modification material includes a thickness of about 0.5 micrometers to about 20 micrometers. In some embodiments, the ceramic material includes a thickness of about 0.2 micrometers to about 25 micrometers. In some embodiments, the thickness is any of at least about 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 micrometers. In some embodiments, the thickness is any of about 0.2 to about 0.5, about 0.5 to about 1, about 1 to about 5, about 3 to about 7, about 5 to about 10, about 7 to about 15, about 10 to about 15, about 12 to about 18, about 15 to about 20, about 18 to about 25, about 0.5 to about 15, about 2 to about 10, about 1 to about 10, about 3 to about 13, about 0.5 to about 15, about 0.5 to about 5, about 0.5 to about 10, or about 5 to about 15 micrometers.
In some embodiments, the ceramic surface modification material is characterized by a water contact angle of about 0° to about 180°. In other embodiments, the water contact angle is less than about 30 degrees. In other embodiments the water contact angle is greater than about 150 degrees.
In some embodiments, the ceramic surface modification material includes a surface area of about 1.1 m2 to about 100 m2 per square meter of projected substrate area. In some embodiments, the ceramic material includes a surface area of about 10 m2 to about 1500 m2 per square meter of projected substrate area. In some embodiments, the surface area is any of at least about 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, or 1500 m2 per square meter of projected substrate area. In some embodiments, the surface area is any of about 10 to about 100, about 50 to about 250, about 150 to about 500, about 250 to about 750, about 500 to about 1000, about 750 to about 1200, about 1000 to about 1500, about 70 to about 1000, about 150 to about 800, about 500 to about 900, or about 500 to about 1000 m2 per square meter of projected substrate area.
In some embodiments, the ceramic material includes a surface area of about 15 m2 to about 1500 m2 per gram of ceramic material. In some embodiments, the surface area is any of at least about 15, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, or 1500 m2 per gram of ceramic material. In some embodiments, the surface area is any of about 15 to about 100, about 50 to about 250, about 150 to about 500, about 250 to about 750, about 500 to about 1000, about 750 to about 1200, about 1000 to about 1500, about 50 to about 700, about 75 to about 600, about 150 to about 650, or about 250 to about 700 m2 per gram of ceramic material.
The substrate on which one or more coating or surface modification materials as described herein are applied or deposited may be composed of any material suitable for the structural or functional characteristics, or functional application of use, for example, in a device, such as a heat exchanger. In some embodiments, the substrate is aluminum or contains aluminum (e.g., an aluminum alloy), a ferrous alloy, zinc, a zinc alloy, copper, a copper alloy, a nickel alloy, nickel, a titanium alloy, titanium, a cobalt-chromium containing alloy, glass, a polymer, a co-polymer, a natural material (e.g., a natural material containing cellulose), or a plastic.
In some embodiments, the substrate includes a metal, and the primary metal in a ceramic surface modification material as described herein is different than the primary metal in the substrate. A primary metal is a metal that is at least about 50%, 60%, 70%, 80%, 90%, or 95% of the total metal in the substrate or the ceramic material, e.g., as determined by x-ray diffraction on an atomic metals basis. Examples of substrate primary metals include, but are not limited to, aluminum, iron, copper, zinc, nickel, titanium, and magnesium. Examples of ceramic primary metals include, but are not limited to, zinc, aluminum, manganese, magnesium, cerium, copper, gadolinium, tungsten, tin, lead, and cobalt.
In some embodiments, the substrate includes a metal that is able to react (e.g., dissolve) under reaction conditions that allow for local dissolution of the substrate metal, and the substrate metal is incorporated into a substrate modification material, such as a ceramic material, e.g., a binderless porous ceramic material. For example, an aluminum substrate may provide aluminum (e.g., Al2+) that is incorporated into ceramic material as the ceramic material is deposited on the substrate.
The following examples are intended to illustrate, but not limit, the invention.
The substrates or assembles to which the coating is applied typically go through a process starting with (a) surface preparation or cleaning, followed by (b) a conversion or primer step, (c) a structured ceramic deposition, and (d) the deposition of another ceramic layer, conversion of the deposited structured ceramic layer, or deposition of a monolayer, paint, oil or resin. In some cases, some of the steps can be bypassed to give a different outcome.
(a) Surface preparation and cleaning step: In the examples below, the surface was prepared as follows. The metallic substrates or assemblies were pot cleaned or wiped with isopropyl alcohol (IPA) and a towel to remove any residual oils. Next, the parts were submerged in a caustic etch bath at pH>10 at a nominal room temperature of 20° C. until a darkening of the surface was observed, or about 15 minutes. The substrates or assemblies were then rinsed in water to remove any residual caustic or loosely adhered material. Next, the parts were submerged in a nitric acid solution with pH below 3 and temperature of 20° C. to remove smut, etch reaction products, intermetallic and surface oxide, or to pickle the substrate, revealing a clean surface. Other surface preparation techniques that result in a clean surface are appropriate are applicable. Polymeric and cellulosic substrates were pot cleaned or wiped with isopropyl alcohol on a towel to remove any residue.
(b) Conversion coating or primer: Conversion coatings and/or primers in the following examples are considered continuous unless otherwise described. Selective coverage was carried out through a partial chemical exposure and/or through the use of masking agents. Conversion coatings or primers consist of films generated through a chemical or electrochemical conversion of the substrate, resulting in a thin film with low porosity when compared to structural ceramic deposition layers described below. Conversion coatings are typically either oxides, phosphates, or chromates and carried out at low pH. Application methods include immersion plating, which can in some cases include the application of electrical bias, or spraying chemical solutions on the substrates to be coated. Inorganic materials such as aqueous acidic chromium (III) phosphate with other metals and anionic reactants to modify the solution pH. Solutions consisting of insoluble solid materials were heated from 40° C.-100° C. with solution/substrate contact from 1 to 90 minutes. Surfactants can be added to enhance the film composition or substrate conversion reaction rate. The surface of the exposed substrate reacts, forming a dense layer, wherein the conversion of the substrate surface provides a diffusion barrier to limit further reaction. A thermal stabilization step can be used to accelerate the formation of conversion layer.
Conversion layers or primers were dried prior to introduction of structural ceramic deposition methods or deposited monolayer/paint/oil/resin layers unless otherwise indicated. Process times between application of conversion layers and subsequent processing was less than 24 h unless otherwise noted.
(c) Structured or porous ceramic deposition: Structured ceramic depositions in the following examples are considered continuous unless otherwise described. Selective coverage was carried out through a partial chemical exposure and/or through the use of masking agents. The substrates or assemblies were then placed into the structured ceramic deposit bath containing 20-500 mM of metal nitrate and a similar amount of an amine (such as ethylene diamine, hexamethylenetetramine, or urea), and were allowed to react prior to the substrate insertion at a reaction temperature of 30-90° C. The assemblies were maintained in the bath until the turbidity dropped below 100 NTU or for about 5 minutes to about 90 minutes. The substrates or assemblies were removed, drained, rinsed and placed into an oven to dry and/or calcine at approximately 100° C.-800C for several hours. The parts were then allowed to cool to room temperature. Structural ceramics were dried prior to deposited monolayer/paint/oil/resin layers unless otherwise indicated.
(d) Deposited monolayer/paint/oil/resin—continuous/selective coverage with/without gradient: Deposited monolayer/paint/oil/resin in the following examples are considered continuous unless otherwise described. Selective coverage was carried out through a partial contact and/or through the use of masking agents. Structural ceramics created in (c) were dried prior to a post processing step, such as a conversion of the deposited ceramic or deposition of a second ceramic that partially or completely filled the porous interconnected ceramic network with a second material, unless otherwise indicated. Substrate temperatures were typically maintained at room temperature, and deposition solutions were typically maintained at ambient room temperatures unless otherwise noted. Deposited monolayer/paint/oil/resin consisted of materials applied to the upper surface layer by painting, spraying, immersion, wicking, vapor phase condensation, and may include thermal or catalytic treatment to expedite drying of the materials and/or increase chemical or mechanical adhesion to the upper surface layers. These processing steps are described in additional detail in each Example as needed.
A heat exchanger (HX) is completely coated in a conversion coating, such as trivalent chromium process (TCP) via an immersion or spray coating process. The manifolds and brazing joints of the manifolds and tubes are subsequently painted via a partial dip or spray coating a particular location on the part. In this particular case, the complete coil is totally immersed to apply a conversion coating. In a subsequent step, the manifolds of the heat exchanger are sequentially dipped into a paint bath. The conversion area of the coil will have corrosion protection while maintaining its heat transfer coefficient while the painted manifolds and manifold-tube joints will have an extra protective layer from corrosion.
A HX is completely coated in a conversion coating, such as TCP, applied to the entire HX via an immersion step. This process step is followed by a complete coating of a paint that is thicker at the bottom of the HX than the top, which is applied via dip coating and encouraging the paint to drain in a preferred orientation resulting in a thicker layer in that orientation. A complete spraying, with additional passes of the sprayer in the desired thicker location would be similar. The regions of thicker paint coating will have an increased corrosion resistance. The top of the HX requires less paint due to the lower exposure time of accumulated liquid, thus lowering production cost of having a uniform thickness across the entire HX while providing the same amount of corrosion protection that also reduces the thermal HX losses by minimizing the application of paint to primarily areas that need protection and/or limiting material applied to critical heat exchange surfaces.
A HX is completely coated in a conversion coating, such as TCP, followed by a complete coating of a paint that is thicker at the bottom of the HX than the top, which is applied in sequential dip coating steps with a sequentially shallower immersion depth. As water accumulates at the bottom of the coil during use, the thicker paint coating at the bottom has an increased corrosion resistance. The top of the HX requires less paint due to the lower exposure time of accumulated liquid, thus lowering production cost of having a uniform thickness across the entire HX while providing the same amount of corrosion protection.
An aluminum containing marine alloy as may comprise the hull of a ship is completely coated in a conversion coating, such as TCP. The alloy is then coated with a corrosion resistant paint via contact or spray painting. The paint is applied in multiple layers in the regions that require additional corrosion protection, such as near the waterline and at the bottom of the hull, to provide scratch protection. The thicker paint layers add more corrosion resistance to the areas most exposed to corrosive environments.
A fin-tube HX coil is completely coated with a primer that has corrosion resistance properties, such as TCP or similar phosphate coating. The HX is then completely modified with a ceramic surface modification in an immersion deposition system. The deposition fluids velocities are modified at different areas of the coil changing the composition of the structured ceramic in the regions with changed velocities. This approach may be used to induce a pore size gradient across the coil. The varying pore size creates variable wicking patterns that can pull water away from areas prone to corrosion.
A brazed aluminum HX is completely coated with a ceramic surface modification primer that has corrosion resistance properties, such as TCP or similar phosphate coating. The manifolds and manifold-tube brazing joints are then coated in a multilayer structured ceramic that prevents corrosive solutions from reaching the HX surfaces at the most vulnerable areas. The structured ceramic material also modifies the manner in which rain, condensate and other applied liquids are retained on the surface. As an example, a structured ceramic layer may have a low contact angle, leading to a thinner liquid layer at the applied locations which would lead to more rapid drying of the surface.
A HX is completely coated with a primer or conversion coating that has corrosion resistance properties, such as TCP or ceria. The upper half of the HX is then modified with a structured ceramic surface modification during which the shear rate is varied to create a gradient in pore size towards the top of the HX. The gradient of pore sizes causes water to wick towards the top of the HX, away from the most vulnerable areas of HX.
A brazed aluminum HX is completely coated with a primer coating followed by a structured ceramic surface modification and an optional functional material layer such as steric acid to provide a surface energy modification. The manifolds and manifold-tube joints are then painted via spray or dip coating to provide additional corrosion protection or an aesthetic look. The main portion of the coil that has had a functional material layer applied has a high contact angle and rejects water from standing on the surface and increases thermal capacity, while the less functional areas that are prone to corrosion are protected by the corrosion resistant paint.
A marine alloy as may comprise the hull of a ship is completely coated in a conversion coating, such as TCP, followed by a complete coating with a structured ceramic surface modification. The hull is then modified with a functional material layered to create a superhydrophobic surface. The functional material layer will be applied such that the bow of the hull is more hydrophobic than the stern. The superhydrophobic surface allows the ship to reduce drag more effectively and/or be more durable at the points of highest water shear rate during operation, while the TCP and ceramic surface modification protects the rest of the hull from the corrosion of sea water.
An HX is completely coated with a conversion coating, followed by a structured ceramic surface modification. The bottom half of the coil is then functional material layered to create a superhydrophobic surface. The bottom half of the coil rejects water condensation and prevent the accumulation of water at manufacturing joints and design features such as the manifold-tube joints, fin-tube joints, or louvers. With the decrease in water accumulation at the most vulnerable areas of the coil, the most vulnerable areas of the coil to corrosion are protected.
An HX is completely coated with a conversion coating, followed by a structured ceramic surface modification. The coil is then coated in a corrosion resistant functional material layer that is thicker on the outside facing side of the HX than the inside facing side. This protects the outside (e.g., environmental or airstream) facing side of the HX from corrosive environments (acid rain, cat urine, etc. or contaminants in the airstream). while the inside facing side (e.g., side that is not exposed to environmental conditions or airstream) exhibits a limited decrease in heat transfer performance. Overall, the pressure drop is reduced relative to a uniform thickness coverage.
A brazed aluminum HX is partially coated with a conversion coating on the manifolds and brazing joints of the manifolds and tubes applied via selective immersion into a process bath. The coated areas prevent corrosion in the areas that are most susceptible to corrosion.
A HX is completely coated in a structured ceramic surface modification, followed by a functional material layer that enhances hydrophobicity to create a superhydrophobic surface. The manifolds and brazing joints of the manifolds and tubes are painted to create a more corrosion resistant area of the coil. The superhydrophobic area of the coil rejects water accumulation during use while the painted manifold and manifold-tube joints protect the more vulnerable areas from corrosion.
An HX is completely coated with a binderless structured ceramic surface modification. The coil is then coated in a corrosion resistant functional material layer that is thicker on the outside facing side of the HX than the inside facing side. This protects the outside facing side of the HX from corrosive environments (acid rain, cat urine, etc.), while the inside facing side exhibits limited decrease in heat transfer performance. Overall the pressure drop is reduced relative to a uniform thickness coverage.
A brazed aluminum heat exchanger was completely coated with a binderless structured magnesium oxide ceramic surface modification that was deposited in a 25 to 100 mM aqueous solution of magnesium nitrate and a similar amount of hexamethylenetetramine at a temperature of about 50° C. to 80° C. for a time period of about 15 to 90 minutes. The coil was then calcined at a temperature of about 400° C. for about 1 hour. The coil was allowed to cool and was then immersed for a second time in a 25 to 100 mM aqueous solution of magnesium nitrate and a similar amount of hexamethylenetetramine at a temperature of about 50° C. to 80° C. for a time period of about 15 to 90 minutes. The coil was then calcined a second time at a temperature of about 400° C. for about 1 hour. The coil was then cooled and partially immersed in a solution containing a room temperature vulcanizing (RTV) silicone at a concentration between 0.5 wt % and 10 wt %, preferably about 2 wt % in tert-butyl acetate. The heat exchanger was immersed such that approximately half of the heat exchanger was in the solution, and approximately half of the heat exchanger was in the vapor space above the solution. The heat exchanger was immersed for about 10 to 300 minutes, preferably about 30 minutes. The heat exchanger was then placed in air for 24 to 72 hours where the RTV silicone formed a superhydrophobic functional layer on the surface of the heat exchanger with a contact angle of >120°. The unfunctionalized portion of the heat exchanger was then placed in an aqueous solution containing an aminoethylaminopropylsilsesquioxane at a concentration of 0.1 wt % to 10 wt %, preferably about 5 wt %. The heat exchanger was immersed for 10 minutes to 240 minutes, preferably about 30 minutes. The heat exchanger was thoroughly rinsed with de-ionized water to remove any remaining solution from the surface and annealed in an oven at an temperatures of 90° C. and 140° C., preferably about 110° C., for 30 minutes to 300 minutes, preferably about 60 minutes. The silsequioxane functionalized structured ceramic was hydrophilic and had a water contact angle of <60°.
On the finished heat exchanger, there was an interface between the RTV functionalized ceramic surface and the silsequioxane functionalized ceramic surface. On the RTV side of this interface, water droplets beaded up and rolled off the surface. On the silsequioxane functionalized ceramic surface, water droplets wetted the surface and spread out along the surface.
A HX was fully coated with a binderless structured ceramic surface modification comprising magnesium and aluminum oxides/hydroxides as described above The HX was dipped in a 25 to 75 mM aqueous solution of magnesium nitrate with a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 120 minutes. The coil was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. A subsequent treatment was carried out by immersion of half of the coil in a bath containing a functional material layer chemical. The functional material, hexadecylphosphonic acid, layer was applied to the bottom half of the coil. The functional material layer created a superhydrophobic surface on the bottom half of the coil.
The heat exchanger was then fitted into a controlled air stream and chilled below the dew point of the air stream using chilled glycol. The upper half of the heat exchanger which contained just the structural ceramic layer generated condensate during the testing which was retained in the heat exchanger body. The lower portion of the heat exchanger that was treated with a functional material layer that resulted in superhydrophobic surface (contact angle>150 degrees) conditions resulted in condensation demonstrating heat exchange but the condensate was not retained in the heat exchanger body during wind tunnel testing wherein condensation was occurring.
A brazed aluminum heat exchanger was completely coated with a binderless structured magnesium oxide ceramic surface modification that was deposited in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The coil was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The coil was allowed to cool and immersed a second time in a 25 to 100 mM aqueous solution of magnesium nitrate and a similar amount of hexamethylenetetramine at a temperature of about 50° C. to 80° C. for a time period of about 15 to 90 minutes. The coil was then calcined a second time at a temperature of about 400° C. for about 1 hour. Two different solutions were created, one was a solution containing a room temperature vulcanizing (RTV) silicone at a concentration of 0.5 wt % to 10 wt %, preferably 2 wt %, in tert-butyl acetate. The other solution was an aqueous solution containing aminoethylaminopropylsilsesquioxane at a concentration of 0.1 wt % to 10 wt %, preferably about 5 wt %. The heat exchanger was placed in a spray chamber and the solutions were each sprayed in a fashion such that one side of the heat exchanger was sprayed with the RTV solution and the other side was sprayed with the aminoethylaminopropylsilsesquioxane solution for 1 minute to 30 minutes, preferably about 5 minutes. The heat exchanger was annealed in an oven at a temperatures of 90° C. to 140° C., preferably about 110° C., for 30 minutes to 300 minutes, preferably about 60 minutes. The silsequioxane functionalized structured ceramic was hydrophilic and had a water contact angle of <60° while the RTV functionalized structured ceramic was hydrophobic and had a contact angle of >120°
On the finished heat exchanger, there was a gradient interface between the RTV functionalized ceramic surface and the silsequioxane functionalized ceramic surface as a result of the spray pattern. When water was sprayed onto the heat exchanger, the water droplets bounced off of the hydrophobic functionalized surface and wicked into the fin pack on the hydrophilic functionalized surface. As water condenses or is introduced to the surface, it can flow from hydrophobic areas to hydrophilic areas and improve the heat transfer of the surface
An aluminum panel was modified with a structured ceramic material of manganese and aluminum oxides that was deposited in a 50 to 150 mM aqueous solution of manganese nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 70° C. to 80° C. for a time period of about 30 to 120 minutes. The panel was then baked at a temperature of about 400° C. for about 1 hour. The panel was then selectively coated with sealant materials such as a drying oils, such as tung oil or linseed oil, or waxes, such as paraffin wax or bees wax, such that about 10% of the top of the panel was not covered with the oil or wax. This allowed for electrical contact to be made to the sample and enables use as an electrode for a battery or capacitor.
A HX coil was completely coated with a magnesium based structured ceramic surface modification comprising magnesium and aluminum oxides/hydroxides. The surface was deposited in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The coil was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The shear rate of the reacting chemical mixture was varied at different areas adjacent to and along the coil, which created a gradient in thickness of the surface modification. A heat exchanger was treated to apply a structured ceramic as described above. A recirculation system moved the processing liquid from the base of the immersion tank to a pump and filter to remove suspended solids from the stream. The liquid was returned to the immersion tank containing a heat exchanger through a liquid eductor, which focused and amplified the liquid motion adjacent to the eductor. The recirculated fluid was directed to the midpoint of one manifold, and along the length of the heat exchanger. The areas of higher shear rate had an increased amount of the ceramic modification with varying pore size. The increased deposition levels were demonstrated through a visual observation of the color of the material along the manifold and heat exchanger surface. Regions of increased deposit were seen to be more white in color than the remainder of the heat exchanger, which had a grey appearance. X-ray fluorescence (XRF) measurements confirmed that the areas that appeared whiter had a higher amount of the magnesium and aluminum oxide surface modification compared to adjacent areas that appeared darker in color. These regions with thicker structural layers can provide additional protection against corrosive elements from the surrounding environment.
A HX coil is completely coated with a structured ceramic surface modification. The coil is placed in a 25-75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The coil was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. During processing, the temperature, concentration, and shear rates are varied to create a denser structure with smaller pore sizes closer to the fins and less dense structure with increased pore sizes in the ceramic deposit further from the fins. The gradient of the ceramic structure with surface modification thickness enhances water wicking properties at the outer areas of the ceramic deposit to decrease drying time, while the increased density and smaller porosity toward the fin surface of the HX minimizes the quantity of water from contacting the substrate. This enhances drying time and onset of frost, while inhibiting corrosion of the surface.
A HX is completely coated with a magnesium oxide based structured ceramic surface modification. The coil is placed in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The coil is then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The shear rate is varied at different areas along the coil, creating a gradient of pore size and altering the topography of the ceramic surface. The HX is then uniformly treated with a functional material layer to create a superhydrophobic surface such as perfuloralkylsilanes, fatty acids, or alkyl phosphonic acids. The gradient created by the ceramic modification creates areas that provide droplet rejection characteristics to control the wettability of certain areas of the coil. These areas of droplet rejection can be focused on areas known to be more vulnerable to corrosion related failures.
A brazed aluminum heat exchanger is immersed into an immersion tank and the part is agitated by oscillation in a direction orthogonal to the primary airflow direction during operation. The part motion results in a greater deposition of a structured ceramic layer at the leading and trailing edges when the primary operation airflow directions are considered than in the central section of the heat exchanger body. This greater deposition rate increases the thickness of material at the leading and trailing edges providing protection. The part is then subsequently treated through the application of a functional material layer on the leading edge (when considering the airflow direction) to provide additional wear and abrasion protection on the leading edge.
An aluminum alloy as may comprise the body of an aircraft is coated with a structured ceramic surface modification. The shear rate is varied such that the front facing portions of the wings, propeller blades, horizontal stabilizers, and rudder have increased variability in topography. The front facing portions of the wings, propeller blades, horizontal stabilizers, and rudder are then treated selectively with a functional material layer. The increased variability in topography from the ceramic surface modification results in the functional material layer possessing a droplet rejection property, which serves to prevent ice formation on the most vulnerable areas of the aircraft. The overall weight of the aircraft is reduced through selective protection.
A HX is completely coated with a structured ceramic surface modification. The shear rate is varied such that the top of the HX has a thicker ceramic layer than the bottom. The bottom half of the coil is then painted via dip or spray painting with a focus on the manifold-tube brazing joints. The thicker areas of the paint protect the more vulnerable areas of the coil while the thicker ceramic layer wicks water away from the underlayers of the paint so water or other corrosive solutions cannot undercut the paint.
A steel-aluminum heat exchanger was coated with a structured ceramic surface modification that has corrosion resistance properties and that was also preferentially deposited on the aluminum fins but not the steel tubes. The coil was placed in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The coil was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The structured ceramic included zinc and aluminum oxides/hydroxides. The ceramic surface was hydrophilic and wicked water from the steel tube to the aluminum fins to allow better water management and improve the heat exchanger's performance, while protecting the steel tubes from corrosion.
An aluminum panel was selectively protected (masked) in a pattern. The panel was masked with silicone tape in a desired pattern and the masked panel was deposited with a structured ceramic. The masked surface was placed in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The masking from the panel was removed and the panel was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. On removal of the masking, a patterned structural ceramic remained, allowing for selective moisture collection (wicking) patterns or moisture removal (draining) patterns. The part also contained a region of bare metal adjacent to the structured layer which may be used for electrical contact with the substrate.
An aluminum panel was selectively protected (masked) in a pattern. The panel was masked in a pattern with a permanent marker containing a dye pigment, a resin, and organic solvents. The masked panel was subsequently coated in a binderless structured ceramic surface modification that included zinc and aluminum oxides/hydroxides. The masked panel was deposited in a 25 to 75 mM aqueous solution of zinc nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The panel was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. During thermal treatment, the dye pigment, resin and organic solvents in the mask were vaporized and oxidized, leaving a bare aluminum substrate. Structural ceramic remained, allowing for selective moisture collection (wicking) patterns or moisture removal (draining) patterns. The part also contained a region of bare metal adjacent to the structured layer which may be used for electrical contact with the substrate.
An aluminum panel was selectively protected (masked) in a pattern. The panel was masked in a desired pattern with a permanent marker containing a dye pigment, a resin, and organic solvents. The masked panel was subsequently coated in a binderless structured ceramic surface modification that included zinc and aluminum oxides/hydroxides. The masked panel was deposited in a 25 to 75 mM aqueous solution of zinc nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The panel was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. During thermal treatment, the dye pigment, resin and organic solvents in the mask were vaporized and oxidized, leaving a bare aluminum substrate. The structural ceramic was then modified with a hexadecylphosphonic acid functional layer which was selective for the ceramic material. This resulted in a superhydrophobic structured ceramic surface near a more hydrophilic bare aluminum surface. The contact angle of water of the functionalized structured ceramic surface was higher than the contact angle for the bare aluminum panel.
An aluminum panel was selectively protected (masked) in a pattern. The panel was masked with polyimide tape in a desired pattern and the masked panel was subsequently coated in a structured binderless ceramic surface modification that included magnesium and aluminum oxides/hydroxides. The panel was deposited in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The panel was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The adhesive in the polyimide tape was vaporized and re-deposited on the surface of the metal, forming a superhydrophobic structured ceramic. Upon removal of the masking, there was a difference in the contact angle between the structured ceramic surface coated with a functional layer and the aluminum surface coated with the same functional layer, due to the presence of the structured ceramic layer.
An aluminum panel is selectively protected (masked) in a pattern. The masked panel is subsequently sprayed or showered to deposit a ceramic surface modification on unmasked surfaces. On removal of the masking, a patterned structural ceramic remains comprising magnesium and aluminum oxides/hydroxides, allowing for selective moisture collection (wicking) patterns or moisture removal (draining) patterns. The spray or shower application of the ceramic material is configured to provide additional deposit coverage to preferential draining locations.
An aluminum panel was selectively protected (masked) in a pattern using a Kapton (polyimide) adhesive tape. The masked panel was subsequently coated with a binderless structured ceramic surface modification that included magnesium and aluminum oxides/hydroxides, as described in Example 29. Silicone tape has also been successfully used on aluminum panels and HX materials. On removal of the masking, a patterned structural ceramic remained. The patterned panel was then dipped in an anodic dye in which the patterned structural ceramic preferentially absorbed the pigment of the dye, changing the color of the structured deposit sections only.
A stainless steel-aluminum heat exchanger was coated with a structured ceramic surface modification that was preferential to the aluminum fins but not the stainless steel or copper tubes. The heat exchanger was coated with a structured ceramic surface by dipping it deposited in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The coil was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The heat exchanger was then functionalized with a monolayer material by dipping it into a dilute solution (0.1-1% by mass) of hexadecylphophonic acid, perfluoroalkylsilanes, fatty acids, or alkyl silanes, to create a superhydrophobic surface on the aluminum fins. The superhydrophobic functional material layer on the fins resulted in droplet rejection properties, which prevented water accumulation on the fins and improved the heat exchanger's performance compared to a similar uncoated heat exchanger. The surface properties also provided a protective layer from corrosion. Because the ceramic surface modification material selectively modified the aluminum fins, less raw materials were used than if the surface modification were applied to both the fins and tubes, resulting in a cheaper process.
An aluminum panel was selectively protected (masked) in a pattern. The panel was masked with polyimide tape in a desired pattern and the masked panel was deposited with a structured ceramic material, and the polyimide material was not removed prior to exposure to elevated temperatures. The panel was placed in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The panel was then calcined at a temperature of about 400° C. to 600° C. for about 1 hour. The resulting panel had a patterned structural ceramic that included magnesium and aluminum oxides/hydroxides and the regions that contained a structural ceramic layer were significantly more hydrophobic than the patterned (covered) areas that did not contain structured ceramic. The masked regions did demonstrate a contact angle difference relative to an untreated panel.
A stainless steel-aluminum heat exchanger is coated with a structured ceramic surface modification that is preferential to the aluminum fins but not the stainless steel tubes. A functional material is then selectively layered onto the ceramic material only due to its chemical bonding selectivity to the ceramic relative to the steel. This creates a superhydrophobic surface on the fins, preventing water from accumulating on the fins, which decrease air flow through the fin pack of the heat exchanger, while maintaining the natural corrosion resistance of the unmodified stainless steel.
A stainless steel-aluminum heat exchanger is coated with a structured ceramic surface modification that is preferential to the aluminum fins but not the stainless steel tubes. The fins are processed longer on one side than the other. This creates a gradient of porosity across the aluminum fins.
A stainless steel-aluminum heat exchanger is coated with a structured ceramic surface modification that is preferential to the aluminum fins but not the stainless steel tubes. The fins have a surface roughness due to the manufacturing process and grain boundaries wherein the structured ceramic material is deposited thicker due to the selective targeting of these areas to mitigate corrosion.
A series of 3003 aluminum Q-panel test substrates were coated with a binderless structured ceramic surface modification comprising magnesium and aluminum oxides/hydroxides and subjected to different flow conditions during the deposit process, as shown in Table 1. The panels were placed in a 25 to 75 mM aqueous solution of magnesium nitrate and a similar quantity of hexamethylenetetramine at a temperature of about 60° C. to 80° C. for a time period of about 30 to 90 minutes. The panels were calcined at a temperature of about 400° C. to 600° C. for about 1 hour.
As shown in Table 1, the velocities, deposit masses and resulting concentrations are relative to the base case, shown in the second row, with the velocity setpoint and resulting mass and concentrations being the reference. The changing flow conditions resulted in changes to the amount of mass deposited as well as the composition of the deposit. All other process parameters, temperatures, compositions, materials remained unchanged. This example illustrates that a processing parameter can be used to generate gradients in the structural properties of the binderless ceramic surface layer to provide useful benefit.
An aluminum heat exchanger is coated with a structured ceramic surface modification and subjected to changing process conditions during processing. The temperature of the processing bath is reduced during the processing, resulting in a change in composition of the structural layer as a function of deposit thickness, as compared to a heat exchanger processed at a uniform temperature.
Alternatively, the chemical composition of the processing bath is increased during the processing, resulting in a change in composition of the structural layer as a function of deposit thickness, as compared to a heat exchanger processed at a uniform chemical composition.
Alternatively, a working fluid with a different temperature than the processing bath is passed through the heat exchanger during processing, resulting in a variable temperature across the heat exchanger surface. The structured ceramic material will then have structural properties consistent with local temperature during processing. In eventual use, the heat exchanger may also have an operating temperature gradient owing to the differences in temperature of the heat exchanger, and as such the desired properties of the ceramic surface layer are aligned with the operational needs of the heat exchanger.
All steel surfaces used for a bridge are coated in a corrosion resistant coating to prevent the corrosion of the steel. The surfaces that will be closest to roadway of the bridge are then painted in a protective paint. This partial paint layer protects the corrosion resistant coating from the harsh chloride ions used in deicing agents. Only areas that will be exposed to deicing agents need the protective paint layer, as opposed to painting all structural steel elements of the bridge, thus decreasing overall painting cost.
A HX is painted with a corrosion resistant paint via dip or spray. The paint is applied such that the paint thickness is thinnest in the middle of the coil and thickest on the outside by the manifolds. The cost of painting is reduced while still maintaining the corrosion protection at the areas most vulnerable to corrosion.
A brazed aluminum HX coil is painted via dip or spray painting on the manifold and manifold-tube brazing joints. This creates a corrosion protective coating around the most vulnerable areas of the coil.
A HX coil is painted with a corrosion resistant paint via dip or spray at the manifold and manifold-tube brazing joints only. A gradient is created by applying multiple layers or varying spray time in selected regions of the substrate. The application of the paint is focused on the manifold-tube brazing joints which are most vulnerable to corrosion related failure. This process vastly decreases the cost of painting, while maintaining corrosion prevention in areas that are most needed. The absence of the paint in the functional area of the coil (fin pack) also prevents loss in the HX performance.
3003 Aluminum panels were tested for improved drying properties as outlined herein. All panels were tested by measuring the mass of a panel subject to controlled ambient conditions ranging from 68-70° F., 30-50% relative humidity (RH), and monitoring the mass on the addition of a quantity of two 100 microliter droplets during a subsequent drying period. The bare panel had a drying rate (as measured by mass loss after droplet addition) of about 3 mg of water/cm2-hr. Similarly, an electrocoated panel with polyurethane UV protection was determined to have a similar drying rate of 3 mg/cm2-hr. Panels coated with various structural ceramic layers, as described in PCT/US19/65978, were determined to have a drying rate of 20 to 50 mg/cm2-hr. Three different structured ceramic layer formulations were applied. One panel included magnesium and aluminum oxides/hydroxides (“Structured ceramic1”), applied as described in PCT/US19/65978. Another panel included magnesium and aluminum oxides/hydroxides (“Structured ceramic2”), deposited under similar process conditions for a shorter period of time. A third panel included manganese and aluminum oxides/hydroxides (“Structured ceramic3”). Results are shown in
Panels similar to those comprising the structural ceramic layer were further treated with a functional material layer comprising hexadecylphosphonic acid to increase the contact angle. The application of 100 microliter water droplets resulted in the droplets rolling off the surface of the panels. No mass measurements are provided, as the droplets rolled off the surface before the first time point.
A series of 3003 aluminum q-panels were coated with a binderless structured ceramic surface modification including magnesium and aluminum oxides/hydroxides, similar to that described in Example 33, and subjected to either an immersion temperature of 70° C. or 80° C., for an immersion time period of 1 minute to 64 minutes. Previous samples made at these same conditions demonstrated that the porosity and pore size distribution of the structured ceramic surface varied as a function of immersion time. The capillary climb of de-ionized water of the samples was measured and the data demonstrated the ability of process parameters to impact how water interacts with the surface. Longer immersion times yielded improved capillary climb, and higher temperature immersion also yielded improved capillary climb. This showed that varying process parameters across the surface of a material can be used to optimize how the surface interacts with water for specific applications. Imaging of the structured ceramic layers with a scanning electron microscope (SEM) demonstrated differences in both nanometer and micrometer scale features. When capillary climb measurements were taken with a bare aluminum q-panel, the air-water interface was unchanged.
Although the foregoing invention has been described in some detail by way of illustration and examples for purposes of clarity of understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced without departing from the spirit and scope of the invention. Therefore, the description should not be construed as limiting the scope of the invention.
All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entireties for all purposes and to the same extent as if each individual publication, patent, or patent application were specifically and individually indicated to be so incorporated by reference.
This application claims priority to PCT Application No. PCT/US2019/065978, filed on Dec. 12, 2019, and claims the benefit of U.S. Provisional Application Nos. 62/989,092, filed on Mar. 13, 2020, 62/989,150, filed on Mar. 13, 2020, 63/038,642, filed on Jun. 12, 2020, 63/038,693, filed on Jun. 12, 2020, and 63/039,965, filed on Jun. 16, 2020, all of which are incorporated herein by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/064396 | 12/11/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62989092 | Mar 2020 | US | |
| 62989150 | Mar 2020 | US | |
| 63038642 | Jun 2020 | US | |
| 63038693 | Jun 2020 | US | |
| 63039965 | Jun 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2019/065978 | Dec 2019 | US |
| Child | 17784502 | US |
