Patent Application
20250198010
This application relates generally to non-triazole imidazoline and amide compounds and their use as corrosion inhibitors to inhibit corrosion in industrial water systems including mixed metal systems.
Corrosion of metal surfaces in water systems is a serious problem. Corrosion can cause undesirable consequences, including loss of heat transfer, increased cleaning frequency, equipment repairs and replacements, shutdowns, environmental problems and the increasing resources and costs associated with each. Some causes of increased corrosion of metal surfaces include high dissolved solids, acidic environments, elevated temperatures, microbiological growth, organic and mineral deposits, and fluids that contain relatively high concentration of gases such as oxygen, hydrogen sulfide, or carbon dioxide.
Ferrous metals such as stainless steel are commonly used in industrial water systems such as for heat exchangers in cooling waters. Stainless steel has good mechanical and physical properties for long service life, as well as generally good corrosion resistance. However, even stainless steel can be subject to pitting and crevice corrosion.
Copper and its alloys (all referred to generally as “yellow metals”) are also commonly used in cooling water treatment systems for heat exchanger tubing, pump impellers, and various other applications due to the natural corrosion resistance and high thermal conductivity of these metals. However, copper and its alloys are not immune to corrosion in cooling water applications especially in the presence of halogen based oxidizing biocides such as hypochlorous acid (HOCl) or hypobromous acid (HOBr), which results in corrosion and possibly failure of heat exchangers. Current corrosion inhibitors for copper and its alloys include triazole-based compounds, i.e., a heterocyclic compound that includes a five-membered ring of two carbon atoms and three nitrogen atoms. Conventional triazole corrosion inhibitors include tolyltriazole (TT), benzotriazole (BZT), and chlorinated tolyltriazole (Cl-TT). The triazoles work as yellow metal corrosion inhibitors by forming an inhibitor film on the surface of yellow metals through bonding with copper. However, the film formed by triazoles can be disrupted by halogen-based biocides (e.g., HOCl), which can lead to corrosion and equipment failure. The film formed by triazoles on the metal surface is also affected by high free chlorine and it requires additional triazole to re-passivate the film for corrosion protection. Additionally, in the bulk water, the triazole inhibitor can react and be degraded by halogen-containing biocide and its corrosion inhibition capacity reduced. Triazole inhibitors and their halogenated derivatives also have high aquatic toxicity which can limit their application in industrial cooling water treatment, and the raw materials required to manufacture triazoles are often impacted by cost fluctuation and supply chain vulnerability.
Imidazoline compounds, such as 2-imidazolines, 3-imidazolines, and 4-imidazolines, are a known class of heterocycles formally derived from imidazoles by the reduction of one of the two double bonds. Alkylamphocarboxylates belong to this group of compounds and are known surfactants. Despite their applications as a surfactant, imidazoline compounds and amide compounds have not previously been considered for use in inhibiting corrosion in industrial water systems.
Industrial water systems, including cooling water systems, present unique challenges in terms of efficacy, toxicity, and cost. Historically, phosphate and triazole-based inhibitor compositions have been considered. But these treatments lack stability and can be toxic. These and other issues are addressed by the present disclosure.
The inventors found that certain non-triazole imidazoline and amide compounds are particularly efficacious and stable in industrial water systems, including cooling water systems. In particular, they found that these compounds have surprising chelating properties dictated by specific functional groups that result in superior corrosion resistance and that will not overreact in the presence of halogens, such as halogen-containing biocides or free chlorine, in the water systems, i.e., they have low Cl2 demand (e.g., 2 mg/L or less, 1.1 mg/L or less, 0.1 mg/L to 1.1 mg/L, or 0.2 mg/L to 0.8 mg/L).
According to one aspect, this disclosure provides a method of inhibiting corrosion of a corrodible metal surface that contacts a water stream in a water system. The method includes introducing into the water stream a treatment composition including at least one of (i) at least one non-triazole derivative of imidazoline compound comprising at least one carboxylic or carboxylate group, at least two nitrogen atoms, and an alkyl group, and (ii) at least one amide compound comprising at least one carboxylic or carboxylate group, at least two nitrogen atoms, and an alkyl group.
This disclosure provides novel non-triazole imidazoline and amide chemistries that are effective to prevent corrosion of metal surfaces in contact with water. The non-triazole imidazoline and amide corrosion inhibitors overcome several of the drawbacks of known triazole-based corrosion inhibitors. In particular, disclosed non-triazole imidazoline and amide corrosion inhibitors have been shown to perform as better corrosion inhibitors for metal surfaces than conventional compounds used in cooling water corrosion inhibition applications. They have low halogen demand while exhibiting good corrosion resistance.
Disclosed non-triazole imidazoline corrosion inhibitors form films on the surface of the metal and provide a hydrophobic barrier. This barrier prevents the transmission of corroding species like oxygen from interacting with the metal surface. These inhibitors and similar derivatives show excellent performance with yellow metals like copper and brass.
In embodiments, the non-triazole imidazoline corrosion inhibitors may include compounds that are non-triazole derivatives of imidazoline and/or amide compounds having at least one carboxylic or carboxylate group and at least two nitrogen atoms. The number of the at least one carboxylic or carboxylate group can be in a range of, for example, 1 to 6, 1 to 4, or 2 to 4. The number of the at least two nitrogen atoms can be in a range of, for example, 2 to 6, 2 to 5, or 2 to 4. These compounds may include two nitrogens and at least 1 carboxylate group in the main chain. Preferably, the compounds include 1 to 2 carboxylate groups. The non-triazole derivatives of imidazoline may be formed by reacting an imidazoline with an aminoamine and reacting the product with a haloacetic acid or salt thereof in the presence of an alkali to hydrolyze the nitrile.
Non-triazole derivative compounds particularly suitable for disclosed applications may include but are not limited to compounds of Formula (I) below:
In Formula (I), R may be a hydrocarbon group that can include from 1 to 20 carbon atoms, from 7 to 20 carbon atoms, from 11 to 20 carbon atoms, or from 13 to 15 carbon atoms, for example. The hydrocarbon group can be linear, branched, cyclic or heterocyclic, aliphatic or aromatic, saturated or unsaturated. The hydrocarbon group can include one or more of the following atoms/moieties: halogen, heteroatom, amino, aminoalkyl, cyano, alkoxy, hydroxyl, polyhydroxyl, thiol, alkythiol, carbonyl, nitro, phosphoryl, phosphonyl, sulfonyl. If non-cyclic, the hydrocarbon can be terminated with an amine or hydroxyl group. If the hydrocarbon group includes heteroatoms, the heteroatoms can be present in the hydrocarbon backbone in numbers of, for example, 1, 2, 3, or 4 heteroatoms, including, e.g., N, O, S, and the hydrocarbon group can also be substituted with a halogen atom. If aromatic groups are present, they can include heterocyclic aromatic groups, including a pyridine group, for example.
The compound of Formula (I) may be sodium dicarboxylethyl coco phosphoethyl imidazoline.
In other embodiments, the non-triazole imidazoline corrosion inhibitors may include amide compounds and amide derivatives having at least one carboxylic or carboxylate group and at least two nitrogen atoms. The number of the at least one carboxylic or carboxylate group can be in a range of, for example, 1 to 6, 1 to 4, or 2 to 4. The number of the at least two nitrogen atoms can be in a range of, for example, 2 to 6, 2 to 5, or 2 to 4. These compounds may include two nitrogens and at least 1 carboxylate group in the main chain.
Amide or amide derivative compounds particularly suitable for disclosed applications may include but are not limited to compounds of Formula (II) below:
In Formula (II), R may be a hydrocarbon group that can include from 1 to 20 carbon atoms, from 7 to 20 carbon atoms, from 11 to 20 carbon atoms, or from 13 to 15 carbon atoms, each R′ may be independently H or C, R″ may be N, a nitrogen-containing group, O, C, OH, or COOH, n may be 1 to 20, 1 to 10, 1 to 6, or 1 to 3, m may be 1 to 20, 1 to 10, 1 to 6, or 1 to 3, and 1 may be 1 to 20, 1 to 10, 1 to 6, or 1 to 3, for example. The hydrocarbon group can be linear, branched, cyclic or heterocyclic, aliphatic or aromatic, saturated or unsaturated. The hydrocarbon group can include one or more of the following atoms/moieties: halogen, heteroatom, amino, aminoalkyl, cyano, alkoxy, hydroxyl, polyhydroxyl, thiol, alkythiol, carbonyl, nitro, phosphoryl, phosphonyl, sulfonyl. If non-cyclic, the hydrocarbon can be terminated with an amine or hydroxyl group. If the hydrocarbon group includes heteroatoms, the heteroatoms can be present in the hydrocarbon backbone in numbers of, for example, 1, 2, 3, or 4 heteroatoms, including, e.g., N, O, S, and the hydrocarbon group can also be substituted with a halogen atom. If aromatic groups are present, they can include heterocyclic aromatic groups, including a pyridine group, for example.
Compounds of Formula (II) may include compounds of Formulas (IIA)-(IIF) below, i.e., disodium cocoamphodipropionate (Formula (IIA)), disodium cocoamphodiacetate (Formula (IIB)), disodium capryloamphodipropionate (Formula (IIC)), sodium cocoamphoacetate (Formula (IID)), disodium dapryloamphodiacetate (Formula (IIE)), and disodium lauroamphodiacetate (Formula (IIF)).
The compounds of Formulas (I) and (II) do not include any triazole groups, and preferably do not include any tetrazole groups. Among the compounds of Formulas (I) and (II), sodium dicarboxylethyl coco phosphoethyl imidazoline, disodium cocoamphodiacetate, sodium cocoamphoacetate, and disodium lauroamphodiacetate are preferred due to their superior corrosion inhibition performance, which, without intending to be bound by theory, is believed to be due to their longer chain lengths.
The non-triazole imidazoline and/or amide compounds described above can be combined with water that is in contact with a metal surface to inhibit or prevent corrosion of the metal surface. In embodiments, the non-triazole imidazoline and/or amide compounds may be introduced into open or closed water systems. Further, the non-triazole imidazoline and/or amide compounds can be applied to the water stream while the water system is on-line. The methods of inhibiting corrosion can be used in aqueous systems including, but not limited to cooling water, cooling towers, water distribution systems, boilers, pasteurizers, water and brine carrying pipelines, storage tanks and the like. In general, water in these aqueous systems is at least 90 wt. % water, at least 95 wt. % water, or at least 99 wt. % water.
The metal surface that is in contact with the treated water can include ferrous metals such as steel (e.g., mild steel, stainless steel, galvanized steel, etc.), aluminum and its alloys, and yellow metals (e.g., copper and copper-based alloys including bronzes, brasses, etc.). In one aspect, it has been discovered that disclosed non-triazole imidazoline and/or amide compounds are particularly useful in inhibiting corrosion of yellow metals. In this regard, the non-triazole imidazoline and/or amide compounds, and in particular compounds of Formula (I) and (II) and derivatives, can prevent corrosion on yellow metals by forming an insoluble protective film on the surface. It is believed that the film is stabilize by a molecular bond with the organic inhibitor and copper and prevents surface interaction with corrosive species.
The water systems may be mixed metal systems. In embodiments, mixed metal systems include systems that include surfaces of two or more metals such as copper or copper alloy metal surfaces and another metal. The other metals may include, but are not limited to, iron, silver, steel, zinc alloy, and aluminum. In embodiments, the other metal may be stainless steel, ferrous steel, and/or galvanized steel.
The water in the aqueous systems may contain a free halogen residual in amounts of from 0 to 20 ppm, from 0.01 to 10 ppm, from 0.1 to 5 ppm, or from 0 to 2 ppm, for example. The water temperature may be from 0 to 200° C., from 0 to 180° C., from 0 to 140° C., from 1 to 120° C., from 1 to 100° C., from 20 to 70° C., from 40 to 60° C., or about 50° C. The water in the aqueous systems may be pressurized. The pH of the water may have a value of from 2 to 12, from 4 to 10, from 6 to 9, from 7.0 to 8.5, from 7.5 to 8.5, or about 8.
The non-triazole imidazoline and/or amide compounds described above can be combined with the water in the water system in amounts that are effective to form a film of the non-triazole imidazoline and/or amide compound(s) on the metal surface and reduce corrosion of the metal surface to a desired degree. The non-triazole imidazoline and/or amide compounds can be added so that the non-triazole imidazoline and/or amide compounds is present in the water in amounts of from 0.01 ppm to 500 ppm, 0.01 ppm to 100 ppm, from 0.01 ppm to 50 ppm, 0.01 ppm to 10 ppm, or from 1 ppm to 3 ppm, for example. The non-triazole imidazoline and/or compounds can be added to the water continuously, periodically, or intermittently.
In embodiments, the treatment composition may be used in conjunction with other corrosion inhibitors. With mild steel, for example, the other corrosion inhibitors may include, but are not limited to, Sn, Al, PO4, and Zn. In other embodiments, the treatment composition may exclude cathodic corrosion inhibitors including, but not limited, to rare earth metals.
The compounds can be added in response to a measured parameter of the water or of the metal surface, including when a measured amount of corrosion inhibitor drops below a predetermined threshold. The compounds can be added in response to a system demand of the system or surface demand of the metal surface.
System demand may be attributed to the presence of oxygen, halogens, other oxidizing species and other components in the aqueous system that can react with or remove, and thereby deactivate or consume, the inhibitor. System demand also includes inhibitor losses associated with bulk water loss through, for example, blowdown and/or other discharges from the treated system. System demand does not, however, include inhibitor that binds to or otherwise reacts with the wetted metal surfaces.
Surface demand is the consumption of the inhibitor attributed to the interaction between the inhibitor and a reactive metal surface. Surface demand will decline as the inhibitor forms a protective film or layer on those metal surfaces that were vulnerable to corrosion. Once all of the wetted surfaces have been adequately protected, the surface demand will be nothing or almost nothing. Because the intermittent feed methods according to embodiments focus on treating the metal rather than treating the water, once the surface demand is reduced to values close to zero, the inhibitor feed amount can be substantially reduced or even terminated for some period of time without compromising the effectiveness of the corrosion inhibition program.
The non-triazole imidazoline and/or amide compounds can be added to the water in sufficient amounts and over a sufficient duration so that a protective film is formed on the corrodible metal surface, and in particular so that the protective film has a thickness that is in a range of from 1 to 150 nm, from 5 nm to 50 nm, or from 10 nm to 20 nm. The thickness of the protective film can be measured by applying a platinum coating to the corrodible metal surface (to enhance visibility of the protective film), imaging a cross-section of the corrodible metal surface with a Scanning Transmission Electron Microscopy (STEM), and then measuring the average protective film thickness from the STEM image as is known in the art. Forming a protective film of this thickness is evidence that inhibitor treatment has formed a uniform robust film that is effective to inhibit corrosion of the metal surface. In some embodiments, the film may take from 5 days to 120 days or from 15 days to 90 days with regular dosing of the inhibitor to achieve a suitable film thickness.
The non-triazole imidazoline and/or amide compounds can also increase the hydrophobicity of the corrodible metal surface, which reduces the wettability of the surface and thereby also reduces the corrosion potential. The increased hydrophobicity of the surface is also an indication that the non-triazole imidazoline and/or amide compounds have formed a protective film on the surface. The hydrophobicity of the corrodible metal surface can be quantified by placing a drop of water on the surface and measuring the contact angle of the droplet in accordance with ASTM D594. The treatment composition can be added in a sufficient amount and for a sufficient duration so that the treated metal surface exhibits a contact angle in a range of from 65 to 85 degrees, from 70 to 80 degrees, or from 72 to 78 degrees, for example. Similarly, the contact angle of the treated metal surface can increase by up to 40%, from 5% to 30%, or from 15% to 25%, for example, as compared to a like metal surface that is not treated with the treatment composition (i.e., having no protective film).
The non-triazole imidazoline and/or amide compounds can be added to the water in the form of a powder or an aqueous solution. If added as an aqueous solution, the non-triazole imidazoline and/or amide can be present in amounts of from 1 to 60 wt. % or from 5 to 40 wt. %, for example.
The non-triazole imidazoline and/or amide inhibitors have improved aquatic toxicity, as compared to conventional azole inhibitors. Accordingly, in some embodiments, the treated water that is in contact with the metal surface is free of or substantially free of triazole compounds, e.g., less than 5 ppm triazole compounds, less than 1 ppm triazole compounds, or less than 0.1 ppm triazole compounds. In particular, the treated water can be free of or substantially free of tolyltriazole, benzotriazole, and chlorinated tolyltriazole.
In some embodiments, the non-triazole imidazoline and/or amide inhibitors can be added to the water in combination with other inhibitor treatment agents including triazoles, polymers, phosphonates, and/or phosphates.
The non-triazole imidazoline and/or amide inhibitors also have improved halogen stability, and remain effective to inhibit corrosion even in the water that contains halogen-containing biocides or free chlorine. In this regard, it is believed that these halogens do not substantially disrupt the film formed by the above-referenced non-triazole imidazoline and/or amide corrosion inhibitors and do not degrade those compounds in the bulk water. Accordingly, in some embodiments, the treated water that is in contact with the metal surface includes at least 0.1 ppm of a halogen-containing biocide and/or free chlorine, at least 0.5 ppm, at least 1 ppm, or from 1 ppm to 10 ppm. Halogen-containing biocides may include, for example, hypochlorous acid or hypobromous acid. Likewise, in some embodiments, methods include combining a halogen-containing biocide with the treated water in addition to the non-triazole imidazoline or amide compound.
In addition to the non-triazole imidazoline and/or amide corrosion inhibitor, other components can be added to the water as part of the treatment, including chelating agents, scale inhibitors, dispersants, biocides (such as the halogen-containing biocide noted above), and combinations thereof. These components can be included as part of a treatment composition with the non-triazole and/or amide corrosion inhibitor or can be added to the water separately. Suitable chelating agents include, for example, citric acid, 2-butenedioic acid (Z), and their derivatives. Other chelating agents may include, but are not limited to, glutamic acid, N,N-diacetic acid, tetrasodium salt (GLDA), methylglycine N,N-Diacetic Trisodium Salt (MGDA), and ethanoldiglycinic disodium salt (EDG). GLDA, MGDA, and EDG have been found to be particularly suitable with amide corrosion inhibitors.
Suitable scale inhibitors and dispersants can include one or more of unsaturated carboxylic acid polymers such as polyacrylic acid, homo or co-polymaleic acid (synthesized from solvent and aqueous routes); acrylate/2-acrylamido-2-methylpropane sulfonic acid (APMS) copolymers, copolymer of maleic and acrylic acid (MA/AA), acrylate/acrylamide copolymers, acrylate homopolymers, terpolymers of carboxylate/sulfonate/maleate, terpolymers of acrylic acid/AMPS; phosphonates and phosphinates including 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP), amino tris methylene phosphonic acid (ATMP), 2-hydroxyphosphonocarboxylic acid (HPA), diethylenetriamine penta(methylene phosphonic acid) (DETPMP), bis(hexamethylene triamine penta(methylene phosphonic acid) (BHMTPMP), phosphinosuccinic oligomer (PSO), tetrapotassium pyrophosphate (TKPP), phosphoric acid; salts of molybdenum and tungsten including nitrates and nitrites; amines such as N,N-diethylhydroxylamine (DEHA), diethyl amino ethanol (DEAE), dimethylethanolamine (DMAE), cyclohexylamine, morpholine, and monoethanolamine (MEA). The other components can be added so that the components are present in the water in amounts of from 0.01 ppm to 500 ppm, 0.01 ppm to 100 ppm, from 0.01 to 50 ppm, for example.
In some embodiments, at least one triazole compound such as tolyltriazole (TTA), benzotriazole (BZT), methylbenzotriazole (MBT), butylbenzotriazole (BuBZT), halogen-stable azole (HST), halogenated azoles, and their salts, may be added. The at least one triazole compound can be added so that the triazole compound is present in the water in amounts of from 0.01 ppm to 5 ppm, 0.01 ppm to 1 ppm, from 0.01 to 0.50 ppm, for example. The non-triazole and/or amide compound is dosed in greater amounts than the triazole. In embodiments, the at least one non-triazole and/or amide compound and the at least one triazole compound may be present in the water in a mass ratio of from 1,000:1 to 50:1, from 500:1 to 100:1, from 300:1 to 100:1, from 250:1 to 150:1, or about 200:1, for example. The inventors found that non-triazole and/or amide corrosion inhibitors in combination with low active triazole compounds result in particularly synergistic corrosion inhibition. The inventors found that the triazole may be added in small amounts and result in synergy while still obtaining the benefit of less toxicity. This combination is synergistic and can be done with substantially reduced aquatic toxicity as compared to using triazoles alone to achieve the same level of corrosion inhibition.
In some embodiments, a sugar acid may be added. The sugar acids may include, but are not limited to, glucaric acid, gluconic acid, glucoheptonate, citric/poly citric acid, ascorbic acid, erythorbic acid, glycolic acid, adipic acid, aqueous and a solvent based polymaleic acid. These acids may be added so that amounts of these acids in the water stream are from 0.01 ppm to 100 ppm, 0.01 ppm to 50 ppm, 0.01 ppm to 10 ppm, from 1 to 10 ppm, or from 1 to 5 ppm, for example. In embodiments, the sugar acid may be a polyol such as, for example, a carbohydrate-derived polyol. In preferred embodiments, the carbohydrate-derived polyol is glucoheptonate.
In some embodiments, a Sn, Al, PO4, Zn, polymaleic acid (PMA), nitrite, molybdate, silicate, or borate compound may be added. These compounds may be added so that amounts of these compounds in the water stream are from 0.01 ppm to 100 ppm, 0.01 ppm to 50 ppm, from 1 to 10 ppm, or from 1 to 5 ppm, for example. The inventors found that the combination of the non-triazole and/or amide corrosion inhibitor and nitrite, molybdate, silicate, or borate compound is particularly beneficial in closed loop systems.
In some embodiments, one or more fluorescent agents can be combined with the non-triazole imidazoline and/or amide inhibitor or added to the water together with the non-triazole imidazoline and/or amide inhibitor to detect and quantify the amount of inhibitor in the water. In embodiments, the fluorescent agents can include a reactive chemical tracer (e.g., PTSA) that interacts with the non-triazole group in a way that affects the fluorescence intensity and a non-reactive chemical tracer such as a tagged polymer. Suitable fluorescent agents that can be used are described in U.S. Pat. No. 10,024,751, the entirety of which is incorporated by reference herein.
Several classes of compounds at various concentrations were tested to determine their potential to inhibit corrosion of copper alloy in aqueous systems to determine their potential to inhibit corrosion of copper alloy in aqueous systems as shown in Table 1 below.
In this example, the imidazoline derivative was sodium dicarboxylethyl coco phosphoethyl imidazoline (SDCPI).
One liter samples of synthetic water were each dosed with the compositions in Table 1. The composition of the synthetic water is shown in Table 2 below.
The apparatus used for the corrosion testing was a Gamry Multiport Corrosion Cell and Gamry Reference 600+ potentiostat with multiplexor. Copper coupons (CDA110) were added to the sample cells containing neutral water (pH 7.5), and the cells were dosed with 50 ppm of scale inhibitor (co-polymer and 2-phosphonobutane-1,2,4-yricarboxylic acid) and heated to 50° C. and maintained at this temperature throughout the testing. The cells were continuously stirred at a speed of 350 rpm. A cylindrical working electrode was submerged into the test solutions, and an LPR sweep (linear polarization resistance) was performed every hour for 18 hours. After the 0.5 hrs mark, 1 ppm of free chlorine was dosed into the corrosion cell. The testing parameters are summarized in Table 3 below.
The corrosion rates (in mpy) over the 18 hour period are shown in Table 4 below and in
Several classes of compounds at various concentrations were tested to determine their potential to inhibit corrosion of copper alloy in aqueous systems to determine their potential to inhibit corrosion of copper alloy in aqueous systems as shown in Table 5 below.
One liter samples of the synthetic water described above with respect to Example 1 were each dosed with the compositions in Table 5 and processed under conditions similar to Example 1.
The corrosion rates (in mpy) over the 18 hour period are shown in Tables 6A and 6B below and in
The classes of compounds and concentrations tested in this example are as shown in Table 7 below.
One liter samples of the synthetic water described above with respect to Example 1 were each dosed with the compositions in Table 7 and processed under conditions similar to Example 1.
The control normalized Cl2 demand over time is shown in
An admiralty brass coupon was immersed in water and a treatment composition of the invention was dosed continuously for one month to maintain a constant concentration of the treatment composition of 20 ppm. The treatment composition includes approximately 3 wt. % of a halogen stable azole (i.e., dosed at 0.6 ppm), 20 wt. % of sodium glucoheptonate (i.e., dosed at 4 ppm), and 7.6 wt. % of sodium cocoamphoacetate (i.e., dosed at 1.52 ppm). The formation of a protective film having a thickness in a range of 10 nm-15 nm was observed with a STEM image. Before the treatment, the coupon was determined to have a contact angle of 62.1 degrees, and after one month of treatment, the treated surface of the coupon was determined to have a contact angle of 74.8 degrees (i.e., the contact angle increased by 20.5%).
It will be appreciated that the above-disclosed features and functions, or alternatives thereof, may be desirably combined into different systems or methods. Also, various alternatives, modifications, variations or improvements may be subsequently made by those skilled in the art. As such, various changes may be made without departing from the spirit and scope of this disclosure.
This application claims the earlier filing date benefit of U.S. Provisional Application No. 63/612,127, which was filed on Dec. 19, 2023, the entirety of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63612127 | Dec 2023 | US |
