Patent Application
20170145580
Various embodiments relate to systems, apparatus and processes for continuous electroceramic coating of coil and wire having surfaces comprising light metals and coated coils of metal and wire produced therefrom.
Coil and wire are often made from metals that include light metals, e.g. aluminum, magnesium, titanium and their alloys. In some instances, the coil or wire may be a dissimilar metal, such as steel, having a coating of light metal. Desirable performance requirements for metal coil and wire include corrosion resistance, environmental endurance (e.g., UV and moisture), creep resistance, as well as relatively high elastic modulus, low density, low coefficient of thermal expansion, and high strength.
Conventional light metal containing coil and wires may be bare, i.e. uncoated, or may be coated with conversion coatings, resin insulating layers and/or paint. The relatively low density (˜1.74-4.51 g/cm3 density compared to 7.8 g/cm3 for iron and 7.75-8.05 g/cm3 for steel), red-rust resistance and strength of light metals and their alloys makes products fashioned therefrom highly desirable for electronic devices, e.g. handheld electronic devices; motor vehicles; aircraft and the like.
A drawback of some light metal containing substrates, e.g. magnesium and aluminum, is susceptibility to corrosion. Exposure to oxygen, moisture and other environmental agents, such as human fingerprint constituents, can cause the light metal surfaces to corrode. This corrosion is both unsightly and reduces strength. Corrosion can be critical in smaller gauge wire, e.g. low voltage aluminum wiring, which is generally concealed from view and subject to loss of functioning due to corroded and broken strands.
One method used to improve corrosion resistance of light metals and their alloys surfaces is anodization, see for example U.S. Pat. No. 4,978,432, U.S. Pat. No. 4,978,432 and U.S. Pat. No. 5,264,113. In anodization, a metal (M) surface is electrochemically oxidized to form metal oxides (MOx) from the metal surface thereby creating a coating layer. Although anodization affords some protection against corrosion, improvements in corrosion performance are desirable. As discussed in U.S. Pat. No. 5,683,522, conventional anodization often fails to form a protective layer on the entire surface of a complex workpiece. Anodizing generally fails to coat edges of sheet metal, which requires extra chemical and mechanical pretreatment steps to render the edges coatable by anodizing. Anodized coatings have been found to contain cracks, some down to the metal surface, at sharp corners. Further, adhesion of paint to anodized magnesium surfaces is often insufficient and improvements are needed. Conventional coil and wire comprising surfaces of light metals and their alloys have been previously coated using other coatings; however, these coatings were limited in flexibility, durability and long term adhesion such that the coating had a short lifespan or had other drawbacks.
Due to the length of the substrate, metal coils and wire are generally manufactured using continuous treatment methods wherein the material is unwound and passed through treatment stations and rewound. Batch coating without unwinding often creates flaws in the coating. Electroceramic coating presents challenges to running a continuous process due to the voltage and current used, high speeds required for industrial coating lines and the need to control metal temper, coating uniformity and content. Thus a need remains for durable, adherent coatings on coil and wire, and methods and apparatus for continuous electroceramic coating of coil and wire.
The apparatus and process for coating disclosed herein provides for continuous electroceramic coating of coils of metal strips and wire. The electrification device in the apparatus, such as a rotating electrical connector, e.g. an electrical slip ring, brushed or brushless, or a liquid mercury rotary contact; or a non-rotating dry anode connection, e.g. a conductive metal contact surface such as aluminum, copper, silver and the like; provides the coil or wire with a high voltage and a high current within a bath of liquid precursor, which in turn causes an electrochemical reaction with the surface of the coil and wire within the bath to form the electroceramic coating comprising metal from the substrate, metal from the liquid pre-cursor, oxygen and, optionally fluorine if present in the liquid pre-cursor. Applicants discovered that a dry anode is particularly useful in the apparatus and processes disclosed herein.
Coil and wire products made utilizing the apparatus and/or process disclosed herein comprise a light metal or light metal alloy surface that has chemically bonded to the metal surface an electroceramic coating comprising metal from the surface, metal from the liquid pre-cursor, oxygen and, optionally fluorine if present in the liquid pre-cursor. The electroceramic coated coil or wire has a specific surface area that is significantly greater than the specific surface area of the bare coil or wire prior to coating.
In one aspect, the invention provides a system for continuously electrolytically coating a metal wire or strip comprising at least one light metal surface, the system comprising components of a bath for an aqueous electrolytic solution containing a precursor for an electroceramic coating on light metal surfaces of a metal wire or strip; a first spool frame adapted to support a first spool for providing the metal wire or strip to the bath; a second spool frame adapted to support a second spool for receiving the metal wire or strip from the bath; an electrification device for electrifying the metal wire or strip and located between the first spool frame and the bath; a plurality of guide members positioned to route the metal wire or strip from the first spool to electrically engage with the electrification device, pass into, through and out of the bath, and be rewound around the second spool, wherein at least one of the plurality of guide members is a bath guide member removably fixed in position in the bath for routing the metal wire or strip into contact with the aqueous electrolytic solution; at least one motor adapted to: unwind the metal wire or strip from the first spool, move the metal wire or strip through the plurality of guide members, and/or rewind the metal wire or strip around the second spool; a cathodic connection positioned in the bath for contacting the aqueous electrolytic solution; and a power source electrically connected to the electrification device and the cathodic connection, the power source providing high voltage and high current to the metal wire or strip through the electrification device, and through the metal wire or strip in the bath to the cathode connection via the aqueous electrolytic solution; wherein the at least one motor is connected to at least one motive assembly capable of imparting movement from the motor to the metal wire or strip. The electrification device may be a dry anode connection comprising at least one of a rotating electrical connector and a non-rotating connection for imparting the high voltage and high current to the metal wire or strip; it may comprise at least one of an electrical slip ring, a liquid mercury rotary contact and a non-rotating electrically conductive contact surface.
In a refinement, the invention provides a system adapted for coating the metal strip moving in a path of travel, the metal strip having a first edge and a second edge approximately parallel to a longitudinal axis of the metal strip, and extending between the first and second edges a first side and a second side parallel to the first side and separated therefrom by a thickness of the metal strip, wherein the cathodic connection comprises at least one cathode in the bath, positioned proximate to the path of travel of the metal strip through the bath and separated from the path by a predetermined distance. In one aspect, the at least one cathode comprises a transverse cathode in the bath positioned transverse to the path of travel of the metal strip through the bath and/or transverse to the longitudinal axis of the metal strip in a plane parallel to the first and second sides, and extending continuously or discontinuously at least 50% of a distance from the first edge to the second edge of the metal strip.
In another aspect, the invention provides a system adapted for coating the metal strip or wire moving in a path of travel wherein the at least one motive assembly is capable of imparting movement to the metal wire or strip such that speeds of from about 25 feet/minute to about 1200 feet/minute for metal strip and/or from about 25 feet/minute to about 5000 feet/minute for metal wire are achieved, while maintaining a residence time in the bath sufficient to form an electroceramic coating on the metal strip or wire of from 1 to 50 microns.
In another aspect, the invention provides a system comprising an electrically insulating material positioned between one of the at least one motors and the at least one motive assembly connected to the motor, and/or on a contact portion of the motive assembly for contacting the electrified metal wire or strip, preferably the at least one motor is an electric motor and the electrically insulating material is positioned between the electric motor and the motive assembly for insulating the electric motor from the metal wire or strip electrified by the electrification device.
In another aspect, the invention provides a system wherein the motive assembly comprises one or more of the plurality of guide members being a motive guide member connected to an output drive of one of the at least one motors, the motive guide member having one or more contact portions for contacting the metal wire or strip and thereby imparting movement from the output drive to the metal wire or strip.
In another aspect, the invention provides a system wherein the components are configured, electrically insulated or electrically isolated such that arcing of the high voltage and high current from electrified components of the system or the electrified metal wire or strip is prevented. In a refinement, at least one of the following components is comprised of an electrically insulating material sufficient to prevent conduction of the high voltage and high current from the power source: the bath; the first spool; the first spool frame; the second spool; the second spool frame; a support frame for the electrification device; at least one of the plurality of guide members; and one of the at least one motive assembly.
In another aspect, the invention provides a system further comprising a cooling system in fluid communication with the bath for cooling the aqueous electrolytic solution and at least partially comprised of an electrical insulating material for preventing conduction of the high voltage and high current.
In another aspect, the invention provides a system comprising a controller connected to and configured to control at least one of the at least one motor, the power source, and an optional cooling system. In a refinement, the controller is connected to the motor and configured to control a speed of the motive assembly for controlling speed of the metal wire or strip to maintain a residence time of the metal wire or strip in the bath.
In another aspect, the invention provides a system wherein during use the electrified metal wire or strip contacts the aqueous electrolytic solution, the high voltage and high current passes from the electrified metal wire or strip acting as an anode to the cathodic connection, thereby forming a plasma around the metal wire or strip with the precursor in the solution, resulting in electroceramic coating deposition.
In another aspect, the invention provides a system wherein the precursor in the aqueous electrolytic solution comprises at least one of a complex metal fluoride and a metal oxyfluoride at acidic pH. In a refinement, the precursor in the aqueous electrolytic solution comprises a source of titanium and a source of phosphorus.
In another aspect, the invention provides a continuous process for forming an electroceramic coating on a metal wire or strip comprising: feeding bare metal wire or strip through a bath having a cathodic connection and containing an aqueous solution comprising a precursor for an electroceramic coating; operating an electrification device in electrical communication with the bare metal wire or strip to thereby electrifying the bare metal wire or strip with a high voltage and a high current; passing electrified bare metal wire or strip through the aqueous solution comprising a precursor for an electroceramic coating in the presence of the cathodic connection thereby passing current from the electrified bare metal wire or strip through the aqueous solution to the cathodic connection; and electrochemically reacting the metal wire or strip with the precursor for an electroceramic coating thereby generating a coated metal wire or strip having an electroceramic coating on at least one surface.
In another aspect, the invention provides a continuous process further comprising controlling at least one of waveform, voltage, amperage, and contact time during a residence time of the electrified metal wire or strip in the bath to thereby produce on the metal wire or strip the electroceramic coating on at least one surface, the coated metal wire or strip having a selected emissivity. In a refinement, the waveform is pulsed DC and the process further comprises controlling the on/off ratio of the waveform.
In another aspect, the invention provides a continuous process further comprising controlling aqueous solution content during a residence time of the electrified metal wire or strip in the bath to thereby produce on the metal wire or strip the electroceramic coating on at least one surface, the coated metal wire or strip having a selected emissivity and/or Taber wear index. In a refinement, the process further comprises controlling the aqueous solution content by controlling the amount of dissolved aluminum in the bath.
In another aspect, the invention provides a continuous process wherein the coating includes a metal/metalloid oxide electroceramic comprising aluminum oxide and titanium dioxide. In another aspect, the invention provides a continuous process wherein the bare metal wire or strip comprises at least one surface of one or more of aluminum, magnesium, titanium, zirconium, aluminum alloy, magnesium alloy, titanium alloy and zirconium alloy.
In another aspect, the invention provides a continuous process wherein electrochemically reacting the metal wire or strip with the precursor in the bath includes providing the metal wire or strip as an anode and providing a cathode in the bath. In another aspect, the invention provides a continuous process wherein electrochemically reacting the metal wire or strip forms a visible light-emitting discharge adjacent to immersed metal wire or strip being coated.
In another aspect, the invention provides a continuous process wherein bare metal wire or strip is fed through the bath from a first spool, the process further comprising cleaning the bare metal wire or strip before feeding the bare metal wire or strip through the bath, continuously collecting coated metal wire or strip onto a second spool; and controlling a speed of an output shaft of an electric motor to control a rotational speed of the one of the first and second spools to maintain a residence time of the metal wire or strip in the bath of five to 30 seconds.
In another aspect, the invention provides a coated metal wire or strip made according to a process of the disclosure wherein the coated metal wire or strip has a surface area that is at least 10 times greater than the bare metal wire or strip's surface area, preferably at least 10 times to about 1000 times greater than the bare metal wire or strip's surface area. In a refinement, the coated metal strip is selected from coated aluminized steel, coated aluminum and coated aluminum alloy strips having a uniform layer of the electroceramic coating present on all surfaces.
In another aspect, the invention provides a coated metal wire or strip wherein the coating comprises, titanium, oxygen and phosphorus, and optionally aluminum and/or zirconium.
In another aspect, the invention provides a coated metal wire or strip wherein the coating comprises titanium present in coating surfaces in an amount of 2-50 wt. %, oxygen present in coating surfaces in an amount of 10-75 wt. %, and phosphorus present in coating surfaces in an amount 2-12 wt. %. In another aspect, the invention provides a coated metal wire or strip wherein the coating comprises magnesium, fluoride, oxygen and at least one additional metal from Groups 1-13 of the periodic table of elements.
In another aspect, the invention provides a coated metal wire or strip wherein the coating comprises metal from the surface, metal from the liquid pre-cursor, oxygen and, optionally fluorine if present in the liquid pre-cursor.
In another aspect, the invention provides a coated metal wire or strip wherein aluminum oxide is present in the coating and aluminum oxide concentration is greater at an interface of the coating and the metal wire or strip and decreases with increasing distances away said interface.
In another aspect, the invention provides a coated metal wire or strip wherein the coating has a thickness being in a range of 0.5 to 50 microns.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, or defining ingredient parameters used herein are to be understood as modified in all instances by the term “about”. Throughout the description, unless expressly stated to the contrary: percent, “parts of’, and ratio values are by weight or mass; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description or of generation in situ within the composition by chemical reaction(s) between one or more newly added constituents and one or more constituents already present in the composition when the other constituents are added; specification of constituents in ionic form additionally implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole and for any substance added to the composition; any counterions thus implicitly specified preferably are selected from among other constituents explicitly specified in ionic form, to the extent possible; otherwise, such counterions may be freely selected, except for avoiding counterions that act adversely to an object of the invention; molecular weight (MW) is weight average molecular weight; the word “mole” means “gram mole”, and the word itself and all of its grammatical variations may be used for any chemical species defined by all of the types and numbers of atoms present in it, irrespective of whether the species is ionic, neutral, unstable, hypothetical or in fact a stable neutral substance with well-defined molecules; and the terms “solution”, “soluble”, and the like are to be understood as including not only true equilibrium solutions but also dispersions that show no visually detectable tendency toward phase separation over a period of observation of at least 100, or preferably at least 1000, hours during which the material is mechanically undisturbed and the temperature of the material is maintained at ambient room temperatures (18 to 25° Celsius). The chemical precursors used for forming the electroceramic coating are preferably free, depending on which light metal is being coated, of the following chemicals: chromium, cyanide, nitrite ions, oxalates; carbonates; silicon, e.g. siloxanes, organosiloxanes, silanes, silicate; hydroxylamines, sodium and sulfur. Specifically, it is increasingly preferred in the order given, independently for each preferably minimized component listed below, that precursor for the electroceramic coating according to the invention, when directly contacted with metal in a process according to this invention, contain no more than 1.0, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002 percent of each of the following constituents: chromium, cyanide, nitrite ions; oxalates; carbonates; silicon, e.g. siloxanes, organosiloxanes, silanes, silicate; hydroxylamines, sodium and sulfur. As used herein the term “coil” will be understood to mean metal sheets and metal strips, generally rectangular in cross-section, that are wound into coils of metal, with or without a central spool or reel around which the metal may be wound.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Metal coil and wire produced according to the disclosure herein have an electroceramic coating chemically bonded thereon which has an increased surface area as compared to the bare metal coil or wire. A metal coil or wire having electroceramic coating deposited thereon may have a specific surface area that is 10 times to 1000 times the specific surface area of the uncoated metal coil or wire, based upon BET measurement according to ASTM C1274-12. A specific surface area is the total surface area per unit mass (m2/g). The increased surface area provides for increased radiative emission from the cable, as well as improved convective cooling. According to one example, the electroceramic coating increases the specific surface area of a metal coil or wire by one to two orders of magnitude, i.e. ten times to one hundred times. Desirably, the increase in surface area is at least a factor of 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 130, 140, 150, 200, 300, 500, 700, or 1000 times that of the uncoated metal coil or wire, and in one example the increase is surface area is in the range of 100 to 1000 times that of the uncoated metal coil or wire. In some embodiments, the surface area is less than 1000, 700, 500, 400, 350, 300, 250, or 225 times greater than the surface area of the underlying coated metal coil or wire, e.g. than that of a bare metal coil or wire. In one example, the specific surface area is 700 times that of the specific surface area of the uncoated metal coil or wire. In a further example, the specific surface area is 700 times that of the specific surface area of the uncoated metal coil or wire, and has an add-on mass of 800 mg/m2. In general, a metal coil or wire having electro-ceramic coating deposited thereon may have a surface area that is about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 130, 140, 150, 170, or 200 times greater than the surface area of the underlying coated metal coil or wire and less than 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 225 times greater than the surface area of the underlying coated metal coil or wire.
The coatings are typically stable in ultraviolet (UV) light to withstand exposure to the sun. Additionally, the coatings may be scratch resistant, and may be able to bend with the coil or wire without cracking, delaminating or breaking. The coatings may be thin such that they do not significantly increase the overall weight of the coil or wire. In one example, the coatings may be 0.1, 0.5 or more up to fifty microns in thickness, may be one to twenty microns in thickness, and may be in the range of ten to fifteen microns, five to ten microns, or eight to twelve microns in further examples.
By practicing the methods of the invention, e.g. controlling the content of the aqueous solution in the electroceramic coating bath, the shade or color of the coating may be varied, for example, by various shades of grey ranging from white to black, with lighter shades of grey providing lower absorption of solar emissions. Darker shades of grey may be used to help the coated surfaces shed ice for example.
The coating on the coil or wire may be a uniform coating having a constant or generally constant thickness on the surface of the coil or about the perimeter of the wire. Desirably, this uniformity is achieved in the absence of a polishing, grinding or other removal of coating. In one embodiment, thickness may vary by 0 to 25%, for example at least 1, 3, 5, 7, 9 or 10%, and desirably no more than 25, 20, 18, 16, 14, or 12%, with higher tolerances being acceptable with thicker coatings. The coating provides for improved emissivity, surface area and heat transfer compared to a similar substrate surface that is bare. The coating on the coil or wire has been demonstrated to pass a T-bend test of 0T-1T showing a high bend strength and high adhesion to the coil or wire to provide flexibility under weathering conditions and subjected forces during manufacture and use.
Typically, conventional corrosion resistant coatings deposited on aluminum surfaces provide less than desirable resistance to heating by the electromagnetic radiation of the sun (solar radiation). One commercially available, chromium-containing corrosion protective coating composition provides an emittance of only 0.22 as measured by ASTM C1371-04a. This is better than the untreated metal surface's emittance of 0.08, but still leaves room for improvement. A conventional uncoated roof exposed to solar radiation can reach temperature up to approximately 60-80 deg. C. A coated roof 10 having an electroceramic coating as disclosed herein exposed to the same solar radiation may reach a temperature up to 30% lower and is more durable than white paint typically used for its high emissivity. The high surface area of the coating contributes to the emissivity. This temperature reduction results in reduced heat transfer to the interior of buildings having the coated roof 10 and reduced energy requirements for cooling of the interiors. In one example, the emissivity of the coating ranges from about 0.5 to 1.00, and in a further example, the emissivity is from 0.6 to 0.80. This shows an improvement of more than twice the emissivity of a conventional chromium passivate used in architecture.
In
The coating causes the cable to have a lower temperature than a conventional energized cable where both are operating under the same electrical load at a temperature up to about 150-180 degrees Celsius, e.g. approximately 160 degrees Celsius. The coated cable may show temperatures of 20, 30, 40, 50, 60, 70, 80 or 100 degrees Celsius lower in temperature than a similar cable having no coating. The electroceramic coated cable can operate up to 10%, 20% or 30% or more lower in temperature than the uncoated cable based on the same load, and desirably operates at temperatures lower than the uncoated cable of at least 1, 3, 5, 7 or 9%. This can provide the benefit of allowing either reduced energy losses from the coated cable, or the ability to increase the current carrying capability of a given cable for a given temperature.
In one example, bare uncoated light metal surfaces of coil or wire are cleaned and the bare surfaces are coated with an electroceramic coating prior to forming steps, for instance before cabling or stamping. In one embodiment, wires 46 in a cable 18 are coated prior to the bundling process to form the finished cable 18. The outer layer wires 46 are singly coated and then placed as the outer wires on the cable 18, thereby only coating the wires that gain the most benefit from having an electroceramic coating on them, i.e. the wires exposed to the external environment. Alternatively, the entire cable may be coated. Coating of strands of wire in a formed cable is particularly useful in low voltage wiring applications where the cables are simply bunches of wire without a formal lay geometry and is performed prior to applying additional layers of resin, enamel, insulation or the like.
The electroceramic UV stable coating may be applied during a continuous process to coils of light metal as part of a manufacturing process that may include, for example unwinding the ribbon or sheet of light metal from the coil, depositing additional layers on the electroceramic coated coil and/or cutting, stamping or otherwise forming the ribbon in the desired shapes or parts. The coating may be applied during a continuous process to individual wires as part of a manufacturing process that may include, for example extruding the wire, adding layers to the coated wire such as resin insulation, and/or forming the wires into mesh, cable, grid, fencing, and the like. Likewise, the coating may be applied during a continuous process to individual metal strips as part of a manufacturing process that may include, for example rolling a billet of metal to form the metal strip, depositing an electroceramic coating having a selected morphology, adding layers to the electroceramic coated metal strip such as resin or paint and/or forming the metal strips for use in architectural, automotive, electrical applications, such as roofs, vehicular and aircraft components, transformer cores and the like. Controlling the morphology of the coating by selecting coating process parameters, for example voltage, current, electrolyte makeup, etc. as described herein, allows production of coated coil and wire having different surface area which affects heat dissipation.
“Continuous” and “continuously” as used herein are meant to include processes that do not involve batch coating. Batch coating may be defined as when all or more than 50% of a coil or wire to be coated is in contact with the electrolyte at one time. By way of non-limiting example, a continuous coil or wire coating process may include a process in which a feed coil or wire to be coated is supplied to the electrolyte bath by passing the coil or wire through the bath. In an example, a continuous process includes processes wherein the product intended to be coated, aluminum coil or wire for example, is passed in a continuous manner into a bath of the electrolyte and the coated coil or wire exits the electrolyte, preferably entry and egress of the coil or wire from the bath may be at the same rate. The leading end of one coil or wire may be attached to the trailing end of the coil or wire ahead of it in the processing line. With the use of an accumulator, which may store up to perhaps 1000 ft. or more of coil or wire ahead of the main section of the processing line, these coil or wire ends can be joined without stopping the main section provided that adequate protection is provided against the current running through the electrolyte and the electrified coil or wire. As a result, the coil or wire being processed through the coating bath need not stop and the process is truly “continuous.” Continuous processes may include intermittent stoppages, by way of non-limiting example for changing of coil or wire spools or maintenance, or be semi-continuous, i.e. continuous manufacturing, but for a discrete time period, without going outside of the scope of the invention.
Advantages of continuous coating of coil or wire include integrated processing with fewer steps; little or no manual handling of the coil or wire; increased safety; shorter processing times; increased efficiency; smaller coating baths and hence less energy consumption and facility space used; a more flexible operation with lower capital costs; smaller ecological footprint; on-line monitoring and control for increased product quality assurance in real-time; and a potential for reduced costs.
Processing herein is run at “high voltage” and “high current” relative to the cross-sectional unit area of the metal coil or wire being coated. These values may be varied while practicing the continuous coating process within power applied ranges of at least 10, 20, 30, 40 or 50 kW per coil or wire. Greater kW may be applied provided the coil or wire has great enough cross-sectional unit area to withstand the added kW without damage to the coil or wire. The voltage and current used in the coating apparatus and process may be varied depending on the mass and surface area of the electrified metal substrate that is in contact with the electrolyte at one time, desired coating weight and morphology. For example, when coating coil, a thin gauge ribbon of aluminum can withstand less voltage and current than a thicker gauge aluminum coil used in for example architectural applications over the same period of contact. Likewise, when coating wire, large gauge aluminum wire can be coated at peak voltage potential of at least about 140 volts up to about 800 volts; at “high current” which as used herein includes effective current of at least about 20 amps and up to about 1000 amps per coil or wire. Small gauge wires, for example wires useful in automotive wire harnesses and wire for signal transmission are desirably coated at voltages ranging from 250 Volts to 500 Volts peak voltage and current of 5 to about 100 amps. Thicker material may support greater amperage to increase coating speed provided that the coil or wire is not damaged by the greater current.
In one embodiment, voltage and current is controlled to supply a selected kW amount over a contact time period, Tc (sec) which is equal to Tf minus Ti, where Ti is the time of initial contact with the electrolyte and Tf is the time of final contact with the electrolyte of a point on the coil or wire passing through the electrolyte in a continuous coating process. Control of the kW passed through the coil or wire during the Tc, as well as the on/off ratio of voltage when using pulsed direct current, work synergistically to deposit uniform electroceramic coatings chemically adhered to low gauge sheets of light metal, e.g. coil metal substrates having thickness values of 0.025 mm to 6.5 mm and individual wires of light metal, at diameters of for example 0.05-25 mm.
Referring to
Alternatively, step 60 may comprise obtaining commercially available bare aluminum coil or wire of desired geometry and providing same to the coating line.
In processes according to the invention, bare coil or wire may be provided on a spool, reel or other coil or wire carrier, which may be used to feed coil or wire into the coating process. Desirably, the coil or wire carrier for feeding the bare coil or wire into the coating process comprises a spool, reel or the like about which the bare coil or wire is wound. Bare coil or wire will be understood by those of skill in the art to mean coil or wire having surfaces of metallic aluminum or an aluminum alloy in the absence of a durable applied coating or sheathing, such as paint, insulation, conversion coatings and the like; bare coil or wire may include some contaminants such as forming lubes, oils, soils and a thin alumina layer formed by environmental oxidation, as well as temporary treatments applied for transport to reduce damage to coil or wire surfaces. Individual wires may have diameters ranging from about 0.05 inches up to not more than 0.375 inches. Suitable wire diameters for overhead conductor applications may be at least 1, 2, 3, 4 mm and not more than about 10, 9, 8, 7, 6, 5 mm. In one example, the bare wire has a diameter of 0.134 inches, although other wire diameters are also contemplated. Spool A in
In one embodiment, the bare coil or wire is coated using a coating sub-process for a coil or wire, shown collectively as block 62. Processes according to the invention may include a greater or fewer number of steps, different variations of a step, and various steps in the process may also be ordered differently from the illustrated flow chart in other embodiments. For example, bare coil or wire having only minor amounts of contaminants on the coil or wire surfaces, may be coated in the absence of a pre-cleaning step or heavily contaminated coil or wires may benefit from a pre-clean step with several sub-steps such as cleaning, pickling and rinsing.
In
At step 66, the coil or wire in the apparatus is electrified to a high current and a high voltage, as described herein, using an electrification device such that the coil or wire acts as an anode within the bath of a solution containing chemical precursors for the coating. A cathode is provided within the bath. Both the electrification device and the cathode are electrically connected to a power source, which when activated passes current to the coil or wire via the electrification device, the electrical current passing from the anodic coil or wire through solution to the cathode.
At step 68, a motor is operated to feed coil or wire through the bath to coat the coil or wire. The type of motor to be used is not particularly limited in any way, and can include for example an electric motor, an internal combustion engine, motors based on pneumatic or hydraulic power or the like. If only for economy, an electric motor is preferred. In one embodiment, speed of the coil or wire is adjustable based on a feedback loop providing data on coating features, such as coating thickness measured, for example in real time or otherwise to a controller. In one embodiment, a user interface is provided for monitoring coil or wire speed, motor parameters and allows making changes to same with adjustment and/or other devices associated with the apparatus.
At step 70, a cleaning device, such as a spray system, an acid or alkaline cleaning bath, ultrasound device, deoxidizing bath and/or an air knife, may be operated to clean the bare coil or wire before it enters the solution in the coating bath. In one example, a spray system provides high pressure deionized water to clean the coil or wire. The cleaning process can provide a better and more uniform substrate surface for coating deposition, and may also reduce introduction of debris or other contaminants into the coating bath.
At step 72, the coil or wire proceeding through the bath is coated via an electrochemical process thereby providing a ceramic coating on the surface of the coil or wire. In one embodiment, the solution in the bath is an aqueous solution containing a coating precursor comprising a source of titanium and a source of phosphorus. In one example, the aqueous solution contains H2TiF6 and a source of phosphorus. An electroceramic coating is deposited on the coil or wire surface which comprises oxides of metals from the substrate and from the solution.
A visible glow or visible light discharge may occur along the surface of the coil or wire as the coating is being formed. The electrochemical process may be a plasma process. The coil or wire may provide an anode connection with oxygen radicals reacting with titanium anions at the surface of the coil or wire to form a titanium oxide, such as titania. Protons at the cathode connection in the bath may lead to formation of hydrogen gas as water in the aqueous solution is electrolyzed, which desirably may be controlled and removed by one or more optional hoods or venting systems. In other examples, other chemical solutions may be used to provide a coated coil or wire.
At step 74, a control system including a controller is used to control the speed of the motor, and the speed of the coil or wire. By changing the speed of the coil or wire, the residence time of the coil or wire in the bath may be controlled, thereby together with other process parameters, controlling the thickness of the coating and the amount of dissolution of aluminum from the coil or wire. Longer residence times for the coil or wire may also be obtained by for example, defining a longer path through the bath. The thickness of the coating and/or the color of the coating may also be controlled by modifying the wave form and/or voltage utilized. The control system is also useful in adjusting spool speed for spools A and B. For coil or wire provided on a spool, to maintain a constant speed of coil or wire travel through the bath as the coil or wire is taken off of spool A, the rotational speed of spool A may be increased to compensate for the smaller amount of coil or wire provided by each rotation. Likewise, as the coated coil or wire accumulates on spool B, to maintain the same feed velocity of the coil or wire, the rotational speed of spool B may be decreased to compensate for the greater amount of coil or wire accumulated during each rotation around the increasing circumference of spool B due to added coated coil or wire. An accumulator, which may store up to perhaps 300 meters or more of coil or wire ahead of the main section of the processing line may be utilized to control coil or wire speed and contact time in the bath. The control system may also control a cooling system connected to the bath to cool the solution and maintain the solution temperature within a predetermined range, desirably from ambient temperature, generally about 20 degrees Celsius to less than 100, 95, 90, 80, 70, 60, 50 or 40 degrees Celsius.
At step 76, after the coil or wire leaves the bath any excess solution remaining on the coated coil or wire may be removed and desirably the coated coil or wire may be rinsed with water or other process steps for removal of electrolyte as are known in the art. In one embodiment, the excess solution, with or without rinse water can be returned to the bath in a recycling process. At step 78, the coated coil or wire is collected onto spool B. When spool A is empty or near empty, the coating process 62 is stopped and spool B containing coated coil or wire is removed from the apparatus.
Although the coating process 62 is described for a single wire or coil, multiple wires or coils may be fed through the bath simultaneously, with each wire or coil being electrified at a high power, as described herein. For simultaneously coating multiple wires or coils, a minimum separation between the electrified wires or coils should be maintained to avoid arcing and each wire or coil may be provided with separate electrification devices and guides as well as supplied from and collected on separate spools. In alternative embodiments, a cable may be fed through the bath such that the outer surface and portions of the interior of the cable are coated.
In one embodiment, the coated coil or wires are polished after removal from the coating apparatus. The polishing step serves to reduce surface roughness and allows for easier handling of the coated wires or coils during later bundling steps. For example, the smoother surface is also less abrasive to uncoated inner wires of a cable, without significantly reducing surface area provided by the electrolytic coating.
At optional step 80, multiple spools of coated cable (spool B) are connected to a cable winding or forming apparatus. The cable is formed by bundling and tensioning the wires to provide a predetermined degree of twist to the various layers in the cable. The twist may be the same between various layers, may be twisted in opposed directions, or the degree of twist vary from layer to layer. In one example, all of the wires in the cable are coated.
In another embodiment, only some or a portion of wires in the cable are coated. At step 82, additional spools of uncoated or bare wire (spool A) may be provided to the cable forming apparatus. A spool of support wire, such as a steel wire, a composite wire, or the like, may also be provided to add additional mechanical strength, such as tensile strength or reduced sag characteristics, to the cable. The uncoated wires and the support wires are positioned to be internal wires within the cable. The coated wires are positioned to form the outer layer of the cable, or the layer that provides the outer perimeter of the cable such that the cable presents a coated outer surface to the environment. The cable is formed by bundling and tensioning the wires to provide a predetermined degree of twist to the various layers in the cable, as described above.
In one embodiment, secondary heat transfer fins such as spine fins, or other durable fins that have a high surface area are also coated according to the invention. These secondary heat transfer fins may be wound on a collecting spool, such as spool B and provided for application to the formed cable using an adhesive or the like, thereby multiplying the outer cable surface area and increasing emissivity.
At step 84, the cable, coil or wire is then provided onto a storage spool or reel. The coil may be installed on a roof as shown in
A metal strip moves in a path of travel through the apparatus and a bath. The metal strip has a first edge and a second edge approximately parallel to a longitudinal axis of the metal strip. The metal strip also has a first side and a second side parallel to the first side and separated therefrom by a thickness of the metal strip. The first and second sides extend between the first and second edges of the strip.
The coil or wire 102 is fed through a bath 108 comprising a container at least partially filled with an aqueous solution comprising a precursor for a ceramic coating on the coil or wire. The container for the bath 108 may be made from a material that is chemically unreactive with the solution. The container for the bath may be electrically conductive to provide a cathode, or may be made from electrically insulating and non-conductive material.
A first frame 110, or main frame, is supported above the bath 108. In one example, the first frame 110 has a lower sub-frame 112, and first and second end supports 114, 116. The frame 110 may be made from non-conductive materials, and in one example, the frame 110 is electrically conductive. Legs or other support members may support the frame 110 on an underlying surface and above the bath 108, as shown or in other configurations.
The first spool 104 is supported by the frame 110 or the first end support 114 by a stationary shaft 128 or spindle. The spool 104 may be removed from the shaft 128 as needed for operation of the apparatus. A fastener may connect with the end of the shaft 128 to retain the spool 104 on the shaft 128 and allow for removal. The shaft 128 is positioned to be generally perpendicular with a section of the coil or wire 102 as it leaves the spool 104, with the coil or wire leaving the spool generally tangentially according to one example. A bearing assembly 130 is provided between the spool 104 and the shaft 128. In one embodiment, the bearing assembly is within the cylindrical section of the spool 104 or on an outer section of the shaft 128 to reduce friction of the spool 104 as it rotates about the shaft 128.
In this embodiment, an electric motor 132 is provided, and in
The second spool 106 is supported by the output shaft 136 of the electric motor 132. The spool 106 may be removed from the shaft 136 as needed for operation of the apparatus. A fastener may connect with the end of the shaft 136 to retain the spool 106 on the shaft 136 and allow for removal. The motor 132 shaft and the inner diameter of the spool 106 may be keyed or splined such that they rotate together. A sleeve 138 made of electrically insulating material is positioned within the barrel of the spool 106 such that the electric motor 132 is electrically isolated from the spool 106. Alternatively, the spool 106 may be made from an electrically insulating material.
In alternative embodiments, the electric motor 132 may be connected to the first spool 104, or each spool 104, 106 may be provided with an electric motor to impart movement to the coil or wire 102 though the bath 108. Alternatively, the coil or wire 102 may be moved using guides that are driven by one or more motors.
A second frame 140, or drop frame, is supported by the main frame 110 and extends away from the main frame 110 such that it may be received within the bath 108. In other examples, the main frame 140 and drop frame 140 are separate components in the system and are not connected to one another. In one example, as shown, the second frame 140 is connected to the lower sub-frame 112. The second frame 140 is positioned such that it is partially submerged within solution in the bath 108. The second frame 140 has at least one guide member 142 to guide the coil or wire through the bath 108. In the example shown, the second frame 140 has first and second members 144 that extend from the first frame 110 with each frame member 144 having a guide member 142 connected to an end region. Each guide member 142 may be a wheel connected to the frame member 144 by a bearing connection, or may be a nonrotating guide member as is known in the art. Each guide member 142 may also be a roller or a pair of rollers for use with a coil, and may extend along the width of the sheet of the coil. The guide members may also include a sheet straightener or alignment device to maintain the positioning of the sheet metal on the coils on the spools and through the bath. Desirably, the frame members 144 are made from an electrically insulating material or an electrically non-conductive material such that electrical current does not pass from the bath 108 to the main frame 110. In one example, the frame members 144 or the frame 140 are made from plastic, such as a plastic or polymer, including, e.g. PVC, CPVC, polyethylene, polypropylene, polyamide, nylon, phenolic resin, as well as non-conductive composites. The frame 140 and guide members 142 are made from or coated with a material that is chemically inert or nonreactive with the solution in the bath. The frame 140 may be removable from the bath 108 for maintenance and other operating considerations.
In
In one embodiment, the electrification device 146 may provide at least 10, 20, 30, 40 or 50 kW per coil or wire and higher provided that the conductor has a great enough cross-sectional area to withstand the added kW without damage to the coil or wire. Current density may be increased for purposes of heating the coil or wire in the bath to temperatures such that the coating is applied and the coil or wire is tempered in the same step in the bath. The electrification device may provide 20-100 kW or more to a single strand of coil or wire in one example, and for a production system may provide 1, 2, 3, 4, 5, 6, 8, 10 or more MW of power across multiple strands of coil or wire running simultaneously through the bath 108. In a further embodiment, the device 146 is one or more rotary switches having a contact wheel that rotates with passage of the coil or wire 102 as the coil or wire is fed from spool 104 to spool 106. The rotary switch of the device 146 may have a liquid mercury rotary contact, which is a rotating electrical connector with an electrical connection made through a pool of liquid metal which transfers the electricity to the contact, thereby providing a low resistance, stable connection. As the mercury contact rotates, the liquid metal maintains the electrical connection between the contacts without wear and with low resistance. The liquid mercury rotary contact is able to provide the high voltage and high current needed to electrify the coil or wire 102. According to one example, the high voltage is a peak voltage at or greater than 125 Volts.
High current is an effective current at or greater than about 20-1000 Amps per coil or wire. As coil or wire size increases so does current carrying capability without damage to the coil or wire. Too much current through a coil or wire may result in excessive heating of the coil or wire, resulting in embrittlement of the coil or wire. Depending upon the gauge of coil or wire to be coated the amperage may be adjusted to at least 20, 30, 40, 50, 60, 70, 80, 90, or 100 Amps and preferably not more than 1000, 400, 300, 200 180, 160, 140, 120 Amps per wire, i.e. a single strand of wire, for high tension wire. Applied current may be alternating current, asymmetric alternating current, direct current, or pulsed direct current. In some examples, direct current is used and may be applied as an on/off waveform. In one embodiment, a total period of the waveform is at least 0.01, 0.1, 1 or 10 milliseconds and up to 50, 40, 30, 20 or 15 milliseconds. Waveforms may be adjusted to a ratio of at least: 0.1, 0.3, 0.6, 1.0, 1.2, 1.5, 1.7, 2.0, 2.2, 2.5, 2.8, 3.0, 5.0, 10.0, or up to an infinite ratio where the direct current is always on and there is no off portion, also referred to as straight DC.
In alternative embodiments, the electrification device 146 may comprise one or more rotating electrical connectors, e.g. an electrical slip ring, brushed or brushless, or a liquid mercury rotary contact; or a non-rotating dry anode connection, e.g. an aluminum or copper contact surface, or other devices. Dry anodes are particularly preferred. Unlike anodizing, where a wet anode may be used, the high voltage, high amperage, lower conductivity of the bath as compared to anodizing renders the wet anode highly inefficient in processes described herein.
One or more cathode connections 148 are provided within the bath 108. The cathode connection 148 may be the container for the bath 108 itself, if the container is electrically conductive; or a component of suitable material, such as metal or graphite, positioned within the bath and in contact with the solution. In one example, for a strip or coil, the cathodic connection includes at least one transverse cathode in the bath, positioned across the path of travel of the metal strip through the bath and separated from the path by a predetermined distance. The at least one transverse cathode in the bath is positioned transverse to the longitudinal axis of the metal strip in a plane parallel or substantially parallel to the first and second sides, and extends continuously or discontinuously at least 50% of a distance from the first edge to the second edge of the metal strip, or at least 50% of the width of the strip.
The electrification device 146 and the cathode connection 148 are connected to a power supply 150. The power supply 150 may be controlled to provide direct current and/or alternating current to the anode and cathode or may provide asymmetric alternating current, for example, with 400-500 Volts peak voltage at the anode, 40-50 Volts at the cathode. In some embodiments, the power may be a square wave form pattern with a frequency of 0.1-40 milliseconds. In other examples, the power supply may provide direct current or pulsed direct current to the anode and cathode. Frequency may be adjusted from 25 Hz to 25,000 Hz, may be high frequency such as 200-25,000 Hz or 100-10,000 Hz. Waveforms may include sinusoidal, triangular, and/or rectangular in any of AC, DC or pulsed DC current, as well as complex waveforms containing superimposed waveforms, e.g. an AC waveform over a DC waveform.
A cooling system 152 is in fluid communication with the bath to maintain the temperature of the solution in the bath. In one example, the cooling system 152 maintains the solution at a predetermined temperature range by cooling the fluid. The temperature range may be greater than the freezing point and less than the boiling point of the solution provided that coating quality is not adversely affected. Generally useful ranges include zero to forty degrees Celsius, twenty to forty degrees Celsius, or other ranges as appropriate. As the coil or wire is electrochemically coated, the solution is heated based on the reaction. The cooling system 152 includes a heat exchanger and may include a pump to circulate and cool the fluid. A fan or the like may be provided to direct air over the heat exchanger to cool the solution. In other embodiments, the solution contained within the bath 108 has sufficient thermal mass, or the electrochemical process does not release sufficient heat to require a cooling system 152.
In one example, at least one cleaning device 154 may be positioned to interact with and clean the coil or wire 102 before it enters the bath 108. The cleaning device 154 may be supported by the frame 110. The cleaning device 154 may be a cleaning bath that chemically removes contaminants or a physical cleaner which removes contaminants by physical impingement, e.g. abrasion, contacting with pressurized fluid, media blasting, burnishing, or polishing, upon the coil or wire. The cleaning device 154 may be a spray system that sprays pressurized fluid across the coil or wire as the coil or wire is fed past the cleaning system to remove any debris or other undesirable material from the surface of the bare coil or wire, such as cutting fluid, etc. The cleaning device 154 may also include a dip tank, and other cleaning systems as are known in the art for use with a continuous system. In other examples, the bare coil or wire is sufficiently clean such that no cleaning device is needed for use with the apparatus 100. In another example, a cleaning device 156 is positioned to interact with the coil or wire 102 after it exits the bath 108.
One or more sets of guides 158 may be provided on the first frame 110 or the second frame 140 to guide the coil or wire 102 to travel along a predetermined path between the first spool 104 and the second spool 106. The guides 158 may be roller guides, including one or two plane guides, or the like. The guides 158 may assist in directing the coil or wire to pass by the cleaning device 154 and/or the air knife 156. The guides 158 may assist in a smooth feed of the coil or wire from the first spool 104. The guides 158 may also present the coil or wire at the appropriate angle to the second spool 106 for a smooth winding and for the appropriate alignment of the coil or wire.
A controller 160 is in communication with the electric motor 132. The controller 160 may be a single controller or multiple controllers in communication with one another. The controller 160 may be connected to random access memory or another data storage system. In some embodiments, the controller 160 has a user interface. The controller 160 is configured to control the electric motor 132, the power supply 150, and the cooling system 152 for startup procedures, shut down procedures, and emergency stop procedures.
It is recognized that any circuit or other electrical device disclosed herein may include any number of microprocessors, integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof) and software which co-act with one another to perform operation(s) disclosed herein. In addition, any one or more of the electrical devices as disclosed herein may be configured to execute a computer-program that is embodied in a non-transitory computer readable medium that is programmed to perform any number of the functions as disclosed herein.
In one embodiment, the controller 160 is in communication with a first sensor 162 and a second sensor 164. The first and second sensors 162, 164 are used with the first and second spools 104, 106, respectively. The first sensor 162 may be a speed and/or position sensor to determine the rotational speed of the first spool 104 or the feed speed of the coil or wire after it exits the spool 104. The first sensor 162 may also include an optical sensor or the like to determine the amount of coil or wire on the first spool 104, for example, the outer diameter of the coil or wire on the barrel of the spool 104. The second sensor 164 may be a speed sensor for the electric motor 132 that senses the rotational speed of the motor shaft, and corresponding speed and/or position of the spool 106. The second sensor 164 may also include an optical sensor or the like to determine the amount of coil or wire on the second spool 106, for example, the outer diameter of the coated coil or wire on the barrel of the spool 106.
The controller 160 controls the speed of the electric motor 132 to control the speed of the second spool 106 and the feed speed of the coil or wire through the apparatus. By controlling the feed speed of the coil or wire 102, the residence time of the coil or wire within the bath 108 is controlled. In one embodiment, the controller 160 controls the motor 132 speed to maintain a residence time, meaning the total time on contact with the solution of a given point on the coil or wire, within a predetermined range or at a predetermined speed. Generally, residence time ranges from about 1, 2, 3, 4, 5, 6, 8, or 10 seconds and at least for efficiency is not more than 180, 160, 140, 120, 100, 60, 45, 30, 20 or 15 seconds. In one example, the residence time is approximately five to ten seconds. Generally, feed rate or coil or wire speed is dependent upon achieving sufficient residence time for desired coating properties, e.g. thickness, surface area and emissivity, and desirably can range from about 10 feet per minute to about 200 feet per minute. Higher speeds may be used provided that residence time is maintained. As the amount of coil or wire on the first spool 104 (and the diameter of the wrap of coil or wire) decreases, the spool must spin faster to provide the same feed rate of coil or wire through the bath. Likewise, as the amount of coil or wire on the second spool 106 (and the diameter of the wrap of coil or wire) increases, the spool 106 must spin slower to provide the same feed rate of coil or wire through the bath. Therefore, the controller 160 uses a closed or open control loop to constantly adjust and control the rotational speed of the electric motor 132 to maintain a generally constant feed rate of coil or wire and residence time.
As the apparatus 100 is operated, bare coil or wire leaves the spool 104 and travels over the electrification device 146 and is electrified with a high current and a high voltage, as described herein, via a dry anode connection. The coil or wire may be an aluminum or aluminum alloy coil or wire in an embodiment. The bare coil or wire then enters the bath 108. The coil or wire is electrified during contact with the bath. In one example, the bath contains an aqueous electrolytic solution containing at least one of a complex fluoride and an oxyfluoride. In other examples, other solutions as disclosed herein may be used. The coil or wire electrochemically reacts with the precursor in the bath by passing a current between the coil or wire in the bath and a cathode in the bath to form the coating. This reaction may form a visible light-emitting discharge adjacent to the coil or wire (or an oxygen plasma) and a hydrogen gas from the water in the aqueous solution. The electrified coil or wire may form a plasma with the liquid precursor, with the bath acting as a cathode and the coil or wire acting as an anode. A coating is formed on the bare coil or wire, and the coating may be a metal/metalloid oxide electroceramic. The coating has an emissivity greater than that of the bare coil or wire. The thickness of the coating is controlled via control of various parameters including but not limited to the residence time of the coil or wire within the bath. The emissivity of the coating may also be adjusted by changing the temperature of the solution in the bath 108, and/or the power provided by the electrification device 146 to a coil or wire. In one embodiment, without changing the bath content, the emissivity can be increased by about 10, 20, 30, 40, or 50% by controlling deposition parameters including waveform, voltage, amperage, and contact time.
The continuous length of the coil or wire 102 is electrified at a high current and voltage, and a cathode is present in the bath 108 such that the coil or wire acts as an anode in the bath 108. The first spool 104, the frame 110, and various guides or devices on the frame 110 may also be electrified. The second frame 140 is made of a non-conductive or insulating material to prevent arcing, formation of the coating on the frame, and to reduce electrical consumption by the apparatus. The electric motor 132 is also electrically insulated from the frame 110 and the coil or wire 102 to prevent electrical shorting of the motor 132.
The second spool of coated coil or wire 102 may be removed from the apparatus 100 and used to form various components or structures such as a roof panel, a stamping blank, a transmission or distribution cable, etc. Multiple spools of coated wire may be combined or bundled to form a cable as shown in
Coating system 210 also includes at least one electrical power supply 222 electrically connected to a cathode 224 located within coating bath container 218, and to an electrification device 226 (dry anode) which electrifies uncoated coil or wire 212 such that the coil or wire 212 acts as an anode in the electrolyte composition E, during operation.
Coating system 210 also includes at least one guide member 228 (two shown in
Coating system 210 includes at least one motive device 232 which moves the coil or wire 212 through the coating system. The motive device 232 is not particularly limited as long as it causes the coil or wire 212 to move through the coating system 210. The motive device 232 typically includes a motor and a motive assembly; suitable motive assemblies may comprise a combination of a motor shaft, rotating guides, tensioning rollers, accumulators and the like. In one embodiment, the motive device 232 may include an electric motor which moves the coil or wire for example by rotating the take-up spool 216 via motor shaft 234 acting as a motive assembly, which may be the sole motive force for moving the coil or wire 212 or may be supplemented by motors drawing the coil or wire through the bath, for example by shoes or rotating guides propelling the coil or wire along its path.
In some embodiments, coating system 210 includes a cooling system 250 in fluid communication with the electrolyte E in bath container 218. The cooling system 250 may provide direct cooling to the electrolyte E or may include a heat exchanger system or the like.
Coating system 210 also includes a controller 236 which is configured to control at least one of the motive device 232, the power supply 222, and the cooling system 250. In operation, the power supply 222 supplies the electrification device 226 with a high voltage and current, as described herein, which is provided to coil or wire 212 when it is in proximity to the electrification device 226, and generally in contact therewith. Coil or wire 212 is unwound from the feed spool 214, contacts the electrification device 226, is electrified thereby and passes into the electrolyte E in bath container 218. Coil or wire 212 passes through the electrolyte E for a residence time sufficient to electrolytically coat coil or wire 212, then coated coil or wire 212 exits the electrolyte E, moves past or through drip guides 240 and is wound onto take-up spool 216. Coated coil or wire 212 may optionally pass through other stages before or after the electrolyte bath, for example a pre-cleaning bath 260, a post rinsing bath 270 which may include a post-coating drying station. One important aspect of the invention is providing appropriate electrical insulation to parts of the coating system 232 which may be damaged by high voltage and current used for coating formation on the coil or wire 212 or, for those parts of the system that do not require such high power, insulating or isolating them from the high power, at least for economy and safety. Hence, while feed spool 214, coating bath container 218, take-up spool 216 and various guides are in contact with the electrified coil or wire 212 or electrolyte E, these parts may either be made of non-conductive materials or physically insulated from other parts of the coating system. For example, the electric motor portion of a motive device 232 may be insulated from the electrified coil or wire by interposing non-conductive contact surfaces which impart movement to the coil or wire 212, but do not conduct electricity back to the motor of the motive device. For example, electrically insulating material 230 may be used to isolate the coil or wire 212. Desirably, at least motors, pumps and the controller are insulated or isolated such that they are not electrified by the high voltage and current supplied to the electrification device 226 and the coil or wire 212.
Various electroceramic coatings may be deposited using the methods and apparatus described in the present disclosure. In one embodiment, the coating comprises titanium, oxygen and phosphorus. In one embodiment, the coating comprises aluminum, titanium, oxygen and phosphorus. In another embodiment, the coating comprises aluminum, titanium, zirconium, oxygen and, optionally phosphorus. In another embodiment, the coating comprises aluminum, zirconium, oxygen and, optionally phosphorus. In yet another embodiment, the coating comprises magnesium, fluoride, oxygen and at least one additional metal from Groups 1-13 of the periodic table of elements.
An example of an electroceramic coating and the associated chemistry, including reactants, to use when generating the coating on a light metal substrate such as aluminum or an aluminum alloy is described in U.S. Pat. No. 6,797,147 issued on Sep. 28, 2004; U.S. Pat. No. 6,916,414 issued on Jul. 12, 2005; and U.S. Pat. No. 7,578,921 issued on Aug. 25, 2009; the disclosures of which are incorporated in their entirety by reference herein.
In one embodiment, an oxide coating which comprises aluminum oxide and titanium dioxide, is formed on the surface of the aluminum coil or wire. Desirably, aluminum oxide is present in the coating in amounts of 1-25 wt. %, with the remainder comprising titanium dioxide and non-zero, small amounts of elements from the bath. In one example, the coating includes aluminum oxide in an amount of at least, 5, 10, 15, 20, 25, or 30 of the total weight of the electroceramic coating. In another refinement, electroceramic coating electroceramic coating includes aluminum oxide in an amount of at most, 80, 75, 70, 60, or 50, or 40 of the total weight of the electroceramic coating. Typically, the metal oxide or oxides other than aluminum oxide are present in an amount of at least 20 10, 15, 20, 25, 30, 35, 40, 45, or 50 weight percent of the total weight of the electroceramic coating. In a variation, the aluminum oxide concentration varies over the thickness of the electroceramic coating being greater at the coating substrate interface and generally decreasing as with increasing distances away from the coil or wire substrate. For example, the aluminum concentration may be 10 to 50 percent higher at 0.1 microns from the interface than at 3, 5, 7, or 10 microns from the interface.
In another embodiment, the emissivity of the coating is modified by changes in the identity of the electroceramic coating precursors in the electrolytic bath, e.g. precursor elements may include Ti, Zr, Zn, Hf, Sn, B, Al, Ge, Fe, Cu, Ce, Y, Bi, P, V, Nb, Mo, Mn, W and Co. In one embodiment, features of the coating are adjusted by changing aluminum and/or zirconium concentration of the aqueous solution. The inclusion of aluminum oxide and/or zirconium oxide advantageously allows the adjustment of coating features, e.g. the color and/or abrasion resistance of the electroceramic coating.
The coil and wire products of the disclosure are useful in architectural, appliance, electronic, vehicular, aerospace and furniture products, the wires may act as conductors of electricity or signals, and the coils may be used in equipment such as transformers. Various embodiments of the present disclosure have associated, non-limiting advantages. For example, the electroceramic coating may provide for reduced corrosion of coil or wire. For example, the electroceramic coating on the coil or outer stands or wires of the cable provides for increased emissivity of the coil or cable and lower operating temperatures or reduced heating. By lowering the operating temperature, the losses from the cable incurred by Joule heating are reduced, and the cable sag is reduced. Also, by operating the cable at a lower temperature, the cable is able to transmit the same amount of electrical power as an uncoated cable more efficiently, or greater amounts of electrical power at the same operating temperature as the uncoated cable. In one embodiment, coils of light metal having an electroceramic coating according to the invention can be useful for cool roof applications where the emissivity of the coated surface can be selected based on coating parameters as described herein. Controlling the morphology of the coating by selecting coating process parameters, for example voltage, current, electrolyte makeup, etc. as described herein, allows production of coated coil and wire having different surface area which affects heat dissipation.
Articles of manufacture according to the disclosure include electroceramic coated light metal surfaces of metal coils having one or more of corrosion resistance of 1000 hours ASTM B113 salt spray with no corrosion from the scribe line; improved bonding of resin or paint layers through control of the electroceramic coating morphology as described herein, in particular pores present in the coating provide anchoring sites for subsequent coating. Articles of manufacture comprising a metal coil and/or wire having electroceramic coated light metal surfaces of as disclosed herein. In another application, coils of light metal having coatings according to the invention can be used in architectural applications, in particular for those coatings comprising titanium, use is made of the catalytic activity of titania to produce architectural articles having coated surfaces which catalyze the reduction of nitrogen oxides to nitrogen and oxygen.
Coils of conductive metal, such as aluminum are useful in transformers, but the layers of metal must be insulated from each other. Deposition of a chemically adherent, durable and uniform electrically insulating layer of electroceramic oxide according to the invention provides a flexible insulating layer for use in transformers which can benefit from improvements in durability as compared to insulation materials of conventional transformers. The process as disclosed herein provides uniform edge coverage of metal coils without edge modification steps.
In other embodiments, the electroceramic coating on strands of wire can provide wire and cable having improved properties, for example, titanium wire and cable are being used increasingly to replace steel in some construction projects due to the low density and high strength of titanium, which substrates can benefit from improved corrosion resistance of the electroceramic coating. Other light metal wire, in particular aluminum and aluminum alloy wires, according to the invention are useful in flexible coaxial cable, a variety of audio or audio and video cable, vehicle signal cable, network cable, data transmission cables, single wire conductor and the like. The wire is also applicable to a variety of electronic components' lead wire, such as capacitors, resistors and the like.
While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention. Additionally, the process and systems in the various embodiments described herein may be extended for use in coating other coil or wire and/or cable for various applications. The coating may also be adjusted using the process as described herein to modify the thickness, porosity, color, emissivity, and other properties based on the desired application for the coil or wire.
An aluminum alloy sample was coated in an aqueous electrolytic deposition bath comprising 5.24 parts zirconium basic carbonate and 20.06 parts hexafluorozirconic acid, at constant temperature and 410 Volts peak for 3 minutes. A DC pulsed square waveform having an on/off ratio of 1:3 was used. The coated sample was removed from the bath, rinsed with water and allowed to dry. Emissivity of the sample was 0.68 at 3.1 microns thickness.
An aluminum alloy sample was coated in an aqueous solution comprising 1 part hexafluorotitanic acid and 1 part hexafluorozirconic acid to 0.375 parts of a source of phosphate, measured as phosphate. The aqueous solution was energized to 450 volts applied at constant temperature for a time sufficient to deposit an electroceramic coating. A DC pulsed square waveform having an on/off ratio of 2.78 was used. The coated sample was removed from the bath, rinsed with water and allowed to dry. Emissivity of the sample was 0.79 at 9.0 microns.
Aluminum alloy samples were coated in an electrolytic deposition bath comprising a phosphate source and hexafluorotitanic acid at constant concentration. All samples were coated in the same bath at constant temperature. Voltage, amperage, time and waveforms were varied, as shown below. Waveforms for pulsed DC current were square. The coated samples were removed from the bath, rinsed with water and allowed to dry. Emissivity of the samples was determined for various combinations of voltage, amperage, time and waveforms used, and the results are shown in the table below.
The above results showed that without changing the bath content, the emissivity can be increased by about 40% from the lowest to the highest emissivity shown, by controlling deposition parameters including waveform, voltage, amperage, and contact time.
An elemental depth profile was taken of the coatings of Example 3 using glow discharge optical emission spectroscopy (GDOES). Amounts of various elements were determined in weight percent at particular distances from the metal surface. For all samples, oxygen content built gradually from initial values of less than 2 wt. % at the substrate, while the Al content dropped precipitously over a span of about 2 microns independent of coating thickness. Surface analyte weight percentages were similar across the samples, as shown in the table below:
Comparing the data from the GDOES analysis of the coatings of Example 3 showed surprising similarities between elemental profiles despite different emissivity values. These results tend to show that coating thickness, waveform of deposition, voltage and amperage work synergistically to produce coatings, that although quite similar elementally, have differing emissivities.
Aluminum alloy samples were coated in an electrolytic deposition bath comprising a phosphate source and hexafluorotitanic acid at constant concentration. All samples were coated in the same bath at constant temperature and voltage. Time and waveforms were varied, as shown below. Waveforms for pulsed DC current were square. The coated samples were removed from the bath, rinsed with water and allowed to dry. Emissivity of the samples was determined for various combinations and the results are shown in the table below.
The above results showed that with bath content and voltage held constant, the emissivity was increased by about 10%, from the lowest to the highest emissivity shown, by controlling waveform and contact time.
Sets of commercially available aluminum alloy wires and representative flat panel samples of the aluminum alloys were coated in electrolytic deposition baths comprising a phosphate source and hexafluorotitanic acid at constant concentration. Voltage, power, time and waveforms were varied, as shown below. Waveforms for pulsed DC current were square. The coated samples were removed from their baths, rinsed with water and allowed to dry. Quality and thickness of the coatings were assessed and the results are shown in the table below.
The emissivity of the representative flat panel sample from the same set, selected to have sufficient flat surface area for taking emissivity readings, was measured. Emissivity of the flat samples was measured to be 0.73±0.03. The above results showed that with bath content held constant, the emissivity can be maintained at a given level by selecting and/or controlling waveform, voltage, power, and contact time (for wire this would generally be distance of travel per unit time through a bath along a path of constant dimension, aka line speed).
A series of aluminum alloy samples were electrolytically coated at constant voltage of 435 V with a constant waveform having an on/off ratio of 2.78, using the electrolyte of Example 3 which had been modified by the addition of dissolved Al, in amounts as shown in the table below. The current applied and the coating time was held constant within each alloy group. The coated samples were removed from the electrolyte, rinsed with water and allowed to air dry. The samples in each alloy group were subjected to Taber abrasion testing using a CS-10 grade abrasive wheel under 500 gram load. After 5000 cycles of testing the weight loss and Taber wear index (TWI) were determined. Average values for both values are shown below.
The above results show that adding Al to the electrolytic bath, changes coating features, e.g. the abrasion resistance and TWI of the resulting coating.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
This application claims the benefit of U.S. provisional application Ser. No. 62/034,358 filed Aug. 7, 2014 and U.S. provisional application Ser. No. 62/034,308 filed Aug. 7, 2014, the disclosures of which are hereby incorporated in their entirety by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62034358 | Aug 2014 | US | |
| 62034308 | Aug 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US15/44267 | Aug 2015 | US |
| Child | 15425667 | US |
