CA3170350A1 - Method for passivating metal surfaces - Google Patents
Method for passivating metal surfaces Download PDFInfo
- Publication number
- CA3170350A1 CA3170350A1 CA3170350A CA3170350A CA3170350A1 CA 3170350 A1 CA3170350 A1 CA 3170350A1 CA 3170350 A CA3170350 A CA 3170350A CA 3170350 A CA3170350 A CA 3170350A CA 3170350 A1 CA3170350 A1 CA 3170350A1
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- Prior art keywords
- acid
- compound
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- peroxide
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- 238000000034 method Methods 0.000 title claims abstract description 68
- 229910052751 metal Inorganic materials 0.000 title description 27
- 239000002184 metal Substances 0.000 title description 27
- 239000000203 mixture Substances 0.000 claims abstract description 91
- 150000001875 compounds Chemical class 0.000 claims abstract description 78
- XOAAWQZATWQOTB-UHFFFAOYSA-N taurine Chemical compound NCCS(O)(=O)=O XOAAWQZATWQOTB-UHFFFAOYSA-N 0.000 claims abstract description 61
- 239000002253 acid Substances 0.000 claims abstract description 56
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 54
- 150000001412 amines Chemical group 0.000 claims abstract description 49
- 150000002978 peroxides Chemical class 0.000 claims abstract description 43
- 125000000542 sulfonic acid group Chemical group 0.000 claims abstract description 40
- 229960003080 taurine Drugs 0.000 claims abstract description 25
- FHHJDRFHHWUPDG-UHFFFAOYSA-N peroxysulfuric acid Chemical class OOS(O)(=O)=O FHHJDRFHHWUPDG-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 11
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 11
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 18
- 125000000217 alkyl group Chemical group 0.000 claims description 12
- 150000007513 acids Chemical class 0.000 claims description 9
- 229940098779 methanesulfonic acid Drugs 0.000 claims description 9
- SNKZJIOFVMKAOJ-UHFFFAOYSA-N 3-Aminopropanesulfonate Chemical compound NCCCS(O)(=O)=O SNKZJIOFVMKAOJ-UHFFFAOYSA-N 0.000 claims description 6
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 6
- QDHFHIQKOVNCNC-UHFFFAOYSA-N butane-1-sulfonic acid Chemical compound CCCCS(O)(=O)=O QDHFHIQKOVNCNC-UHFFFAOYSA-N 0.000 claims description 5
- CCIVGXIOQKPBKL-UHFFFAOYSA-M ethanesulfonate Chemical compound CCS([O-])(=O)=O CCIVGXIOQKPBKL-UHFFFAOYSA-M 0.000 claims description 5
- RJQRCOMHVBLQIH-UHFFFAOYSA-M pentane-1-sulfonate Chemical compound CCCCCS([O-])(=O)=O RJQRCOMHVBLQIH-UHFFFAOYSA-M 0.000 claims description 5
- KCXFHTAICRTXLI-UHFFFAOYSA-N propane-1-sulfonic acid Chemical compound CCCS(O)(=O)=O KCXFHTAICRTXLI-UHFFFAOYSA-N 0.000 claims description 5
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 4
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 4
- RCLLNBVPCJDIPX-UHFFFAOYSA-N 1-(2-chloroethyl)-3-[2-(dimethylsulfamoyl)ethyl]-1-nitrosourea Chemical compound CN(C)S(=O)(=O)CCNC(=O)N(N=O)CCCl RCLLNBVPCJDIPX-UHFFFAOYSA-N 0.000 claims description 3
- VJKJOPUEUOTEBX-TURQNECASA-N 2-[[1-[(2r,3r,4s,5r)-3,4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]-2,4-dioxopyrimidin-5-yl]methylamino]ethanesulfonic acid Chemical compound O[C@@H]1[C@H](O)[C@@H](CO)O[C@H]1N1C(=O)NC(=O)C(CNCCS(O)(=O)=O)=C1 VJKJOPUEUOTEBX-TURQNECASA-N 0.000 claims description 3
- JCMLWGQJPSGGEI-HZAMXZRMSA-N 2-[[2-[(2s)-2-[(3r,5s,7r,8r,9s,10s,12s,13s,14s,17r)-3,7,12-trihydroxy-10,13-dimethyl-2,3,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydro-1h-cyclopenta[a]phenanthren-17-yl]propyl]selanylacetyl]amino]ethanesulfonic acid Chemical compound C([C@H]1C[C@H]2O)[C@H](O)CC[C@]1(C)[C@@H]1[C@@H]2[C@@H]2CC[C@H]([C@@H](C[Se]CC(=O)NCCS(O)(=O)=O)C)[C@@]2(C)[C@@H](O)C1 JCMLWGQJPSGGEI-HZAMXZRMSA-N 0.000 claims description 3
- WBWWGRHZICKQGZ-UHFFFAOYSA-N Taurocholic acid Natural products OC1CC2CC(O)CCC2(C)C2C1C1CCC(C(CCC(=O)NCCS(O)(=O)=O)C)C1(C)C(O)C2 WBWWGRHZICKQGZ-UHFFFAOYSA-N 0.000 claims description 3
- AFCGFAGUEYAMAO-UHFFFAOYSA-N acamprosate Chemical compound CC(=O)NCCCS(O)(=O)=O AFCGFAGUEYAMAO-UHFFFAOYSA-N 0.000 claims description 3
- 229960004047 acamprosate Drugs 0.000 claims description 3
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 3
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 3
- FYAQQULBLMNGAH-UHFFFAOYSA-N hexane-1-sulfonic acid Chemical compound CCCCCCS(O)(=O)=O FYAQQULBLMNGAH-UHFFFAOYSA-N 0.000 claims description 3
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 claims description 3
- 125000001972 isopentyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])C([H])([H])* 0.000 claims description 3
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims description 3
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 3
- 150000003141 primary amines Chemical class 0.000 claims description 3
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 3
- WBWWGRHZICKQGZ-GIHLXUJPSA-N taurocholic acid Chemical compound C([C@@H]1C[C@H]2O)[C@@H](O)CC[C@]1(C)[C@@H]1[C@@H]2[C@@H]2CC[C@@H]([C@@H](CCC(=O)NCCS(O)(=O)=O)C)[C@@]2(C)[C@H](O)C1 WBWWGRHZICKQGZ-GIHLXUJPSA-N 0.000 claims description 3
- AJKIRUJIDFJUKJ-UHFFFAOYSA-N taurolidine Chemical compound C1NS(=O)(=O)CCN1CN1CNS(=O)(=O)CC1 AJKIRUJIDFJUKJ-UHFFFAOYSA-N 0.000 claims description 3
- 229960004267 taurolidine Drugs 0.000 claims description 3
- 229950010168 tauromustine Drugs 0.000 claims description 3
- 229950011342 tauroselcholic acid Drugs 0.000 claims description 3
- 150000003512 tertiary amines Chemical class 0.000 claims description 3
- 229960003570 tramiprosate Drugs 0.000 claims description 3
- DBMBAVFODTXIDN-UHFFFAOYSA-N 2-methylbutane-2-sulfonic acid Chemical compound CCC(C)(C)S(O)(=O)=O DBMBAVFODTXIDN-UHFFFAOYSA-N 0.000 claims description 2
- FKOZPUORKCHONH-UHFFFAOYSA-N 2-methylpropane-1-sulfonic acid Chemical compound CC(C)CS(O)(=O)=O FKOZPUORKCHONH-UHFFFAOYSA-N 0.000 claims description 2
- XCJGLBWDZKLQCY-UHFFFAOYSA-N 2-methylpropane-2-sulfonic acid Chemical compound CC(C)(C)S(O)(=O)=O XCJGLBWDZKLQCY-UHFFFAOYSA-N 0.000 claims description 2
- HYZYOKHLDUXUQK-UHFFFAOYSA-N 3-methylbutane-1-sulfonic acid Chemical compound CC(C)CCS(O)(=O)=O HYZYOKHLDUXUQK-UHFFFAOYSA-N 0.000 claims description 2
- DPPPKJMOPYULFX-UHFFFAOYSA-N C(C)(C)(C)C(CCCCC)S(=O)(=O)O Chemical compound C(C)(C)(C)C(CCCCC)S(=O)(=O)O DPPPKJMOPYULFX-UHFFFAOYSA-N 0.000 claims description 2
- 230000002378 acidificating effect Effects 0.000 claims description 2
- HNDXKIMMSFCCFW-UHFFFAOYSA-N propane-2-sulphonic acid Chemical compound CC(C)S(O)(=O)=O HNDXKIMMSFCCFW-UHFFFAOYSA-N 0.000 claims description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 69
- 238000002161 passivation Methods 0.000 description 55
- 229910001220 stainless steel Inorganic materials 0.000 description 31
- 238000005260 corrosion Methods 0.000 description 26
- 230000007797 corrosion Effects 0.000 description 26
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 23
- 229910017604 nitric acid Inorganic materials 0.000 description 23
- 239000010935 stainless steel Substances 0.000 description 21
- 150000002739 metals Chemical class 0.000 description 13
- 238000012360 testing method Methods 0.000 description 12
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical group [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 11
- 229910000831 Steel Inorganic materials 0.000 description 11
- 239000010959 steel Substances 0.000 description 11
- 229910052804 chromium Inorganic materials 0.000 description 9
- 239000011651 chromium Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 6
- JHWIEAWILPSRMU-UHFFFAOYSA-N 2-methyl-3-pyrimidin-4-ylpropanoic acid Chemical compound OC(=O)C(C)CC1=CC=NC=N1 JHWIEAWILPSRMU-UHFFFAOYSA-N 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- 238000004140 cleaning Methods 0.000 description 5
- 239000000356 contaminant Substances 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- 238000013459 approach Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 239000012530 fluid Substances 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910001105 martensitic stainless steel Inorganic materials 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 208000009043 Chemical Burns Diseases 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910002065 alloy metal Inorganic materials 0.000 description 1
- 239000003139 biocide Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003183 carcinogenic agent Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000013527 degreasing agent Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 231100001231 less toxic Toxicity 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000008447 perception Effects 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/50—Treatment of iron or alloys based thereon
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- ing And Chemical Polishing (AREA)
Abstract
Method for passivating a metallic surface, said method comprising: - providing said metallic surface; - exposing said metallic surface to a modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C; wherein said composition A comprises: - sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition; - a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide; wherein said composition B comprises: - an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition; wherein said composition C comprises: - sulfuric acid; - a compound comprising an amine moiety; - a compound comprising a sulfonic acid moiety; and - a peroxide; for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
Description
METHOD FOR PASSIVATING METAL SURFACES
FIELD OF THE INVENTION
The present invention is directed to a novel method to passivate metals, more specifically it is directed to a method using a modified Caro's acid to passivate metals.
BACKGROUND OF THE INVENTION
Metal passivation, in the fields of chemistry and engineering, refers to the generation of a coating on a material to render the latter less prone to being affected or corroded by its surrounding environment.
This coating renders the surface of the material passive.
The coating which renders the material passive is formed by a chemical reaction with the base material, or in some cases, it is formed by exposing the material to air so as to oxidize it. Generally, the coating involves a metal oxide which is quite unreactive and hence ideal for exposure to various solutions and environments. This layer of metal oxide provides protection against corrosion, which would decrease the material's lifespan.
Metal passivation is a post-fabrication method of maximizing the inherent corrosion resistance of a stainless alloy from which the workpiece was produced. It is not a scale removal treatment, nor is it like a coat of paint. Passivation provides valuable corrosion resistance of parts and components machined from stainless steels. Properly conducted passivation can prevent premature failure of metals, but when not properly conducted, it may actually provide weak points for corrosion to begin.
Passivation can be best understood as a deliberate-controlled corrosion. Once in a passivation bath, the acid dissolves, or corrodes, free iron (or other alloy metals) at the surface of the metal. This is done in a controlled and uniform manner so long as the bath parameters, such as temperature, acid concentration and exposure time, are followed. When the reaction is not properly overseen, a runaway reaction of corrosion can occur and is referred in the industry as a "flash attack." When a metal undergoes a flash attack, it can develop a dark and damaged or etched surface.
Proper passivation requires at least two steps: the cleaning of the metal followed by exposure of the metal to a passivation bath.
Date Regue/Date Received 2022-08-12 Cleaning metals prior to exposing them to a passivation bath is a critical step, as various contaminants, however small they may be, can find their way onto a metallic surface and generate weak points on the metallic surface where corrosion may take hold. Contaminants such as grease, coolant or other shop debris must be thoroughly cleaned from the surface to obtain the best possible corrosion resistance. It is important when performing passivation of metals that a number of steps be taken beforehand. With respect to various metals which have been machined, machining chips must be removed, and this can be simply by wiping off the metal piece. A subsequent step can include the use of a commercial degreaser or cleaner to remove various oils or fluids used in the machining step.
Should the oils not be removed or not be properly removed, one can expect the formation of gas bubbles on the surface of the metal being passivated. The presence of gas bubbles will impede the passivation and may create weak spots on the passivated metal piece. In some cases, an accumulation of chlorides can lead to a "flash attack" which leaves a heavily etched or darkened surface, in essence, damage to the surface which was destined to be protected through passivation.
It becomes evident that proper steps need to be taken when understanding that these passivated metals are used in many critical industries including, but not limited to, aerospace, medical and dental, and various other industries.
Passivating Baths After thorough cleaning, the stainless-steel part is ready for immersion in a passivation acid bath.
A number of conventional approaches are currently widespread in the field:
nitric acid passivation, nitric acid with sodium dichromate passivation, and citric acid passivation.
The preferred passivation approach typically depends on the type of stainless steel and the acceptance criteria. Today, both nitric acid and citric acid passivation are widely used and relied upon in many industries. Both passivation approaches have shown effectiveness in passivating numerous types of stainless steel and are extensively described in the industry standards ASTM
A967 and AMS 2700. It is worth noting that passivation of titanium is governed by ASTM F86, which only specifies passivation by exposure to nitric acid.
Stainless steels which can be passivated using citric acid at temperatures above 120 F, include:
Austenitic: Martensitic-PH; Ferritic (type 430); Martensitic; and Austenitic-FM. Stainless steels which can
FIELD OF THE INVENTION
The present invention is directed to a novel method to passivate metals, more specifically it is directed to a method using a modified Caro's acid to passivate metals.
BACKGROUND OF THE INVENTION
Metal passivation, in the fields of chemistry and engineering, refers to the generation of a coating on a material to render the latter less prone to being affected or corroded by its surrounding environment.
This coating renders the surface of the material passive.
The coating which renders the material passive is formed by a chemical reaction with the base material, or in some cases, it is formed by exposing the material to air so as to oxidize it. Generally, the coating involves a metal oxide which is quite unreactive and hence ideal for exposure to various solutions and environments. This layer of metal oxide provides protection against corrosion, which would decrease the material's lifespan.
Metal passivation is a post-fabrication method of maximizing the inherent corrosion resistance of a stainless alloy from which the workpiece was produced. It is not a scale removal treatment, nor is it like a coat of paint. Passivation provides valuable corrosion resistance of parts and components machined from stainless steels. Properly conducted passivation can prevent premature failure of metals, but when not properly conducted, it may actually provide weak points for corrosion to begin.
Passivation can be best understood as a deliberate-controlled corrosion. Once in a passivation bath, the acid dissolves, or corrodes, free iron (or other alloy metals) at the surface of the metal. This is done in a controlled and uniform manner so long as the bath parameters, such as temperature, acid concentration and exposure time, are followed. When the reaction is not properly overseen, a runaway reaction of corrosion can occur and is referred in the industry as a "flash attack." When a metal undergoes a flash attack, it can develop a dark and damaged or etched surface.
Proper passivation requires at least two steps: the cleaning of the metal followed by exposure of the metal to a passivation bath.
Date Regue/Date Received 2022-08-12 Cleaning metals prior to exposing them to a passivation bath is a critical step, as various contaminants, however small they may be, can find their way onto a metallic surface and generate weak points on the metallic surface where corrosion may take hold. Contaminants such as grease, coolant or other shop debris must be thoroughly cleaned from the surface to obtain the best possible corrosion resistance. It is important when performing passivation of metals that a number of steps be taken beforehand. With respect to various metals which have been machined, machining chips must be removed, and this can be simply by wiping off the metal piece. A subsequent step can include the use of a commercial degreaser or cleaner to remove various oils or fluids used in the machining step.
Should the oils not be removed or not be properly removed, one can expect the formation of gas bubbles on the surface of the metal being passivated. The presence of gas bubbles will impede the passivation and may create weak spots on the passivated metal piece. In some cases, an accumulation of chlorides can lead to a "flash attack" which leaves a heavily etched or darkened surface, in essence, damage to the surface which was destined to be protected through passivation.
It becomes evident that proper steps need to be taken when understanding that these passivated metals are used in many critical industries including, but not limited to, aerospace, medical and dental, and various other industries.
Passivating Baths After thorough cleaning, the stainless-steel part is ready for immersion in a passivation acid bath.
A number of conventional approaches are currently widespread in the field:
nitric acid passivation, nitric acid with sodium dichromate passivation, and citric acid passivation.
The preferred passivation approach typically depends on the type of stainless steel and the acceptance criteria. Today, both nitric acid and citric acid passivation are widely used and relied upon in many industries. Both passivation approaches have shown effectiveness in passivating numerous types of stainless steel and are extensively described in the industry standards ASTM
A967 and AMS 2700. It is worth noting that passivation of titanium is governed by ASTM F86, which only specifies passivation by exposure to nitric acid.
Stainless steels which can be passivated using citric acid at temperatures above 120 F, include:
Austenitic: Martensitic-PH; Ferritic (type 430); Martensitic; and Austenitic-FM. Stainless steels which can
2 Date Regue/Date Received 2022-08-12 be passivated using citric acid at temperatures below 120 F, include: Ferritic-FM (Types 430F & 430FR);
Ferritic-FM (Chrome Core 18-FM); Ferritic-FM (Type 409Cb-FM); and Martensitic-FM (Type 416).
Stainless steels which can be passivated using nitric acid (typically at 20 vol.%) at temperatures above 120 F, include Austenitic stainless steel. Stainless steels which can be passivated using nitric acid (typically at 20 vol.%) at temperatures below 120 F but in the presence of sodium dichromate (Na2Cr207), include: Martensitic-PH; Ferritic (type 430); Martensitic; Austenitic-FM;
Ferritic-FM (Types 430F &
430FR); Ferritic-FM (Type 409Cb-FM); and Martensitic-FM (Type 416).
Nitric Acid Passivation Nitric acid is a mineral acid which is a hazardous chemical in that it emits toxic and corrosive fumes.
It requires special attention to ventilation and safe chemical handling. It is highly reactive to skin and can rapidly cause severe chemical burns. Nitric acid emissions in the atmosphere have been associated with acid rain and smog and can even impact the ozone layer. These and other factors explain the high degree of oversight with respect to nitric acid and its handling and use, which translate into rigorous requirements for safety in handling and environmental protection.
Stainless steels which may be more prone to etching (flash attack) during the passivation in nitric acid can benefit from the addition of sodium dichromate passivating composition. Other options to reduce the risk of flash attacks during nitric acid passivation include the use of higher concentrations of nitric acid as well as higher bath temperatures. While these options to reduce flash attacks may work, they also increase the risk to personnel safety. It is worth noting that sodium dichromate is a hexavalent chromium compound, which is a known carcinogenic substance.
Citric Acid Passivation In comparison to nitric acid passivation, citric acid passivation offers a generally safer and more environmentally friendly approach to passivation.
Citric acid is an organic acid which is safer for operators than nitric acid as it is low fuming and much less toxic than its nitric acid counterpart. Citric passivation is widely used as it meets current industry standards and is applicable to most types of stainless steel.
In the past, some manufacturers regarded citric acid passivation negatively due to the possible mould growth in the citric acid baths. Nowadays, citric acid passivation has overcome this perception, since
Ferritic-FM (Chrome Core 18-FM); Ferritic-FM (Type 409Cb-FM); and Martensitic-FM (Type 416).
Stainless steels which can be passivated using nitric acid (typically at 20 vol.%) at temperatures above 120 F, include Austenitic stainless steel. Stainless steels which can be passivated using nitric acid (typically at 20 vol.%) at temperatures below 120 F but in the presence of sodium dichromate (Na2Cr207), include: Martensitic-PH; Ferritic (type 430); Martensitic; Austenitic-FM;
Ferritic-FM (Types 430F &
430FR); Ferritic-FM (Type 409Cb-FM); and Martensitic-FM (Type 416).
Nitric Acid Passivation Nitric acid is a mineral acid which is a hazardous chemical in that it emits toxic and corrosive fumes.
It requires special attention to ventilation and safe chemical handling. It is highly reactive to skin and can rapidly cause severe chemical burns. Nitric acid emissions in the atmosphere have been associated with acid rain and smog and can even impact the ozone layer. These and other factors explain the high degree of oversight with respect to nitric acid and its handling and use, which translate into rigorous requirements for safety in handling and environmental protection.
Stainless steels which may be more prone to etching (flash attack) during the passivation in nitric acid can benefit from the addition of sodium dichromate passivating composition. Other options to reduce the risk of flash attacks during nitric acid passivation include the use of higher concentrations of nitric acid as well as higher bath temperatures. While these options to reduce flash attacks may work, they also increase the risk to personnel safety. It is worth noting that sodium dichromate is a hexavalent chromium compound, which is a known carcinogenic substance.
Citric Acid Passivation In comparison to nitric acid passivation, citric acid passivation offers a generally safer and more environmentally friendly approach to passivation.
Citric acid is an organic acid which is safer for operators than nitric acid as it is low fuming and much less toxic than its nitric acid counterpart. Citric passivation is widely used as it meets current industry standards and is applicable to most types of stainless steel.
In the past, some manufacturers regarded citric acid passivation negatively due to the possible mould growth in the citric acid baths. Nowadays, citric acid passivation has overcome this perception, since
3 Date Regue/Date Received 2022-08-12 some formulations now contain biocides aimed at preventing organic growth and mould. In fact, citric acid passivation has become increasingly popular with manufacturers who want to want to steer clear of the nitric acid compositions and especially those containing sodium dichromate.
These compositions can be very difficult to dispose of and are subject to more regulations than citric acid. Citric acid is considered environmentally friendly, which explains its widespread acceptance.
Nonetheless, citric acid passivation requires close monitoring of immersion time, bath temperature and concentration in order to avoid "flash attack" which would otherwise mar or damage the metal being passivated.
In fact, laboratory tests have shown that passivation with citric acid was more likely to cause "flash attack" than passivation with nitric acid. Some of the reasons for the occurrence of flash attacks can be found in excessive bath temperature, excessive immersion time and contaminants present in the baths. Citric acid compositions used in metal passivation contain chemicals such as, but not limited to, corrosion inhibitors and other additives (such as wetting agents) that are said to minimize the occurrence of flash attacks.
It has been noted that another advantage of citric acid passivation is that it involves, in many cases, shorter passivation times versus nitric acid passivation.
When passivating metals using citric acid, it is important to monitor the temperature, the time of immersion and the concentration of the acid so as to avoid any possible runaway corrosion referred to as a flash attack. Some advantages of using citric acid passivation rather than nitric acid passivation include the following:
- no emission of toxic and corrosive gases during the process;
- lower handling requirements in terms of safety equipment;
- lower concentration of acid is required;
- lower overall cost to use;
- process can be carried out a room temperature in the case of some metals and without the need for ventilation;
- uses environmentally friendly chemicals, especially important when it comes time to dispose of spent acid; and - the process does not lead to corrosion of the equipment employed.
These compositions can be very difficult to dispose of and are subject to more regulations than citric acid. Citric acid is considered environmentally friendly, which explains its widespread acceptance.
Nonetheless, citric acid passivation requires close monitoring of immersion time, bath temperature and concentration in order to avoid "flash attack" which would otherwise mar or damage the metal being passivated.
In fact, laboratory tests have shown that passivation with citric acid was more likely to cause "flash attack" than passivation with nitric acid. Some of the reasons for the occurrence of flash attacks can be found in excessive bath temperature, excessive immersion time and contaminants present in the baths. Citric acid compositions used in metal passivation contain chemicals such as, but not limited to, corrosion inhibitors and other additives (such as wetting agents) that are said to minimize the occurrence of flash attacks.
It has been noted that another advantage of citric acid passivation is that it involves, in many cases, shorter passivation times versus nitric acid passivation.
When passivating metals using citric acid, it is important to monitor the temperature, the time of immersion and the concentration of the acid so as to avoid any possible runaway corrosion referred to as a flash attack. Some advantages of using citric acid passivation rather than nitric acid passivation include the following:
- no emission of toxic and corrosive gases during the process;
- lower handling requirements in terms of safety equipment;
- lower concentration of acid is required;
- lower overall cost to use;
- process can be carried out a room temperature in the case of some metals and without the need for ventilation;
- uses environmentally friendly chemicals, especially important when it comes time to dispose of spent acid; and - the process does not lead to corrosion of the equipment employed.
4 Date Regue/Date Received 2022-08-12 In terms of overall process stability, citric acid passivation is less prone to time and temperature variation than nitric acid passivation. Furthermore, citric acid passivation does not emit any hazardous vapors.
In light of the state-of-the art, there exists a need for a new composition which can be used for the passivation of stainless steel which shows advantages not shared with conventional composition and methods associated therewith. The inventors have surprisingly and unexpectedly discovered a new acid composition and method to passivate metals using a composition which overcome some of the drawbacks of each one of the known and conventionally used passivation methods.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, there is provided a method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
Date Regue/Date Received 2022-08-12 for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
According to a preferred embodiment of the present invention, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1. Preferably, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no more than 15:1:1. According to another preferred embodiment of the present invention, said sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
Preferably, said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds. According to a preferred embodiment of the present invention, said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid;
tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethy1-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of CI-Cs linear alkyl and C1-05 branched alkyl. Preferably, said linear alkylaminosulfonic acid is selected form the group consisting of: methyl; ethyl (taurine); propyl; and butyl. Also preferably, said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl;
isobutyl; and isopentyl. More preferably, said compound comprising an amine moiety and a sulfonic acid moiety is taurine. According to a preferred embodiment of the present invention, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; butanesulfonic acid;
pentanesulfonic acid; hexanesulfonic acid; and combinations thereof.
According to a preferred embodiment of the present invention, said sulfuric acid and compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
According to another aspect of the present invention, there is provided a method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- an alkylsulfonic acid; and - a peroxide;
wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the Date Regue/Date Received 2022-08-12 composition.
Preferably, the method uses an aqueous acidic composition comprising:
- an alkylsulfonic acid; and - a peroxide; wherein said alkylsulfonic acid; and said peroxide are present in a molar ratio of no less than 1:1. Preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; butanesulfonic acid;
pentanesulfonic acid; hexanesulfonic acid; and combinations thereof. More preferably, said alkylsulfonic acid is methanesulfonic acid.
According to a preferred embodiment of the present invention, the method further comprises a compound comprising an amine moiety. Preferably, the compound comprising an amine moiety is a primary amine. More preferably, the compound comprising an amine moiety is an alkanolamine. More preferably, said alkanolamine is selected from the group consisting of:
monoethanolamine; diethanolamine;
triethanolamine; and combinations thereof.
According to a preferred embodiment of the present invention, the compound comprising an amine moiety is a tertiary amine. More preferably, said alkanolamine is triethanolamine.
According to an aspect of the present invention, there is provided a method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film, wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition. Preferably, the sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1:1:1.
sulfuric acid, said compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the compound comprising an amine moiety has a molecular weight below 300 g/mol.
According to a preferred embodiment of the present invention, the compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids and combinations thereof.
Preferably, said alkylsulfonic acid is selected from the group consisting of:
alkylsulfonic acids where the alkyl groups range from C1-C6 and are linear or branched; and combinations thereof.
DETAILED DESCRIPTION OF THE INVENTION
It will be appreciated that numerous specific details have been provided for a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered so that it may limit the scope of the embodiments described herein in any way, but rather as merely describing the implementation of the various embodiments described herein.
According to a preferred embodiment of the present invention, there is provided a method for the passivation of a steel surface, wherein said method comprises the steps of:
- providing said steel surface to be passivated;
- cleaning said steel surface to remove oil and other contaminants;
- exposing said steel surface to a modified Caro's acid for a period of time sufficient to form a layer of metal oxide thereon, wherein said modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and Date Regue/Date Received 2022-08-12 - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
According to a preferred embodiment of the present invention, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1. Preferably, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no more than 15:1:1. Preferably also, said sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
According to a preferred embodiment of the present invention, said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of:
taurine; taurine derivatives; and taurine-related compounds. Preferably, said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid;
tauromustine; 5-taurinomethyluridine and 5-taurinomethy1-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of CI-Cs linear alkyl and CI-Cs branched alkyl. Preferably, said linear alkylaminosulfonic acid is selected from the group consisting of: methyl; ethyl (taurine); propyl; and butyl. Preferably, said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl;
isobutyl; and isopentyl. Most preferably, said compound comprising an amine moiety and a sulfonic acid moiety is taurine.
According to a preferred embodiment of the present invention, said compound comprising an amine moiety is an alkanolamine is selected from the group consisting of:
monoethanolamine; diethanolamine;
triethanolamine; and combinations thereof.
According to a preferred embodiment of the present invention, said compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids and combinations thereof.
Date Regue/Date Received 2022-08-12 Preferably, said alkylsulfonic acid is selected from the group consisting of:
alkylsulfonic acids where the alkyl groups range from C1-C6 and are linear or branched; and combinations thereof. More preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid;
propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof. More preferably, said compound comprising a sulfonic acid moiety is methanesulfonic acid.
According to a preferred embodiment of the present invention, there is provided a method for the passivation of a steel surface, wherein said method comprises the steps of:
- providing said steel surface to be passivated;
- cleaning said steel surface to remove oil and other contaminants;
- exposing said steel surface to a modified Caro's acid for a period of time sufficient to form a layer of metal oxide thereon, wherein said modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, said alkylsulfonic acid; and said peroxide are present in a molar ratio of no less than 1:1.
According to a preferred embodiment of the present invention, in Composition C, said sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1:1:1.
According to a preferred embodiment of the present invention, in Composition C, said sulfuric acid, said compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is stainless steel.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a stainless steel selected from the group consisting of: Austenitic;
Martensitic-PH; Ferritic; Martensitic;
Austenitic-FM; Ferritic-FM; and Martensitic-FM.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Austenitic stainless steel, having a chromium content ranging from 15.0 to 23.5 %.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Austenitic stainless steel and is selected from the group consisting of:
Type 304/304L; Type 316/316L;
Type 305; Custom Flo 302HQ.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Martensitic-PH stainless steel having a chromium content ranging from 11.0 to 17.5 %.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Martensitic-PH stainless steel and is selected from the group consisting of: Custom 630 (17Cr-4Ni);
Custom 450; Custom 455; Custom 465T; and 15Cr-5Ni.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Martensitic stainless steel, having a chromium content of less than 15 %.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Martensitic stainless steel and is selected from the group consisting of:
Type 410; Type 420; and TrimRite .
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic stainless steel having a chromium content above 16 %.
Preferably, said Ferritic stainless steel is type 430.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic stainless steel having a chromium content of less than 12 %.
Preferably, said Ferritic stainless steel is type 409.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Austenitic-FM stainless steel having a chromium content ranging from 17 to 19 %. Preferably, said Austenitic-FM stainless steel is type 303.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic-FM stainless steel having a chromium content above 16 %.
Preferably, said Ferritic-FM
stainless steel is selected from the group consisting of: type 430F; 430FR;
and Chrome Core 18-FM.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic-FM stainless steel having a chromium content of less than 13 %.
Preferably, said Ferritic-FM
stainless steel is type 409Cb-FM.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Martensitic-FM stainless steel having a chromium content of less than 13 %. Preferably, said Martensitic-FM stainless steel is type 416.
Conventional nitric acid baths are changed when, upon titration, it is deemed that the solution is no longer capable of providing proper passivation. Another indicator used to decide whether to discard the acidic solution is by visual inspection and assessing the color of the bath.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the passivation bath using a modified Caro's acid, is able to process more metal than a conventional passivation bath. Moreover, it can extend its useful lifetime (i.e., period of time until the bath chemicals need to be discarded and replaced) by adding the peroxide component at intervals where the bath is known to start to lose its passivation efficiency.
Experiments to passivate various steels Various steel coupons were exposed to a composition comprising a modified Caro's acid as set out previously in order to assess the resulting passivated coupon's ability to withstand corrosion through acid exposure.
Corrosion of a Modified Caro's acid to treat Stainless Steel The purpose of this experiment is to test the corrosion rates of stainless steel in the presence of a modified Caro's acid and the corrosion rates of stainless steel after exposure to the delignification blend.
Procedure Corrosion tests were completed in glass sample jars in a heated water bath.
For each condition listed in Table 1, the coupon was washed with acetone, air dried, and weighed, before being suspended in the test fluid. The fluid in each glass sample jar was pre-heated to temperature before exposing the coupon to the acid blend. After the exposure period, the coupon was removed, washed with water, followed by an acetone wash, air dried, and then weighed. The corrosion rate was determined from the weight loss, and the pitting index (Appendix A) was evaluated visually at 40X magnification, and a photo of the coupon surface at 40X magnification was taken.
Table 1 lists the various compositions which were tested in the corrosion testing. The corrosion testing was carried out for a duration of 24 hours at a temperature of 30 C
(86 F) under atmospheric pressure.
Table 1: Listing of the compositions and coupons tested Test Coupon type Test fluid A 316SS 40 wt% sulfuric acid B-1 304SS Delignification blend C-1 316SS Delignification blend B-2 304SS 70 wt% sulfuric acid C-2 316SS 70 wt% sulfuric acid Date Regue/Date Received 2022-08-12 The corrosion test results are shown Table 2, and in Figure 1 to Figure 2.
Figure 1: Surface of 304SS coupon from corrosion test B-2 at 40X Magnification. Figure 2: Surface of 316SS coupon from corrosion test C-2 at 40X Magnification.
Table 2: Results of the corrosion testing of treated and untreated coupons at 30oC under atmospheric pressure for a duration of 24 hours Test Coupon # Corrosion rate Pitting index mm/year lb/ft2 A 325 40.756 0.180 9 B-1 19 0.014 0.000 0 C-1 310 0.000 0.000 0 B-2 19 0.002 0.000 0 C-2 310 0.007 0.000 0 Pitting index scale found in Finggar, M.; Jackson, J. Corrosion Science, 2014, 86, 17-41 Conclusion From the above experiments, it was found at the tested conditions that the modified Caro's acid composition was not corrosive to 304SS and 316SS (coupons B-1 and C-1).
Moreover, exposure of coupons B-1 and C-1 to a modified Caro's acid according to a preferred method of the present invention clearly passivated their surfaces. This is confirmed by subsequent exposure of those coupons to 70 wt% }12504, which resulted in an unblemished surface (as indicated by the photographs taken of the coupons now labelled B-2 and C-2.
Moreover, after the exposure to the modified Caro's acid, the steel coupons of 304SS and 316SS
were resistant to sulfuric acid corrosion at the tested conditions, whereas coupons not exposed to the modified Caro's acid were heavily corroded by sulfuric acid.
According to a preferred embodiment of the present invention, the compositions used for passivation of metals such as stainless steel can be reused be simply adding more peroxide. When used for passivating metals, the compositions consume the peroxide component and thus can be re-used a great number of times without losing effectiveness, as the consumable peroxide can be replenished by simply adding it to the used composition. This is a significant advantage over standard nitric acid and citric acid solutions, as they lose effectiveness over time and must be disposed of entirely.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the passivation method is employed to replace passivation by citric acid and treats metals used in a wide variety of industries, including but not limited to aerospace, medical, industrial and manufacturing industries.
While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be appreciated by those skilled in the relevant arts, once they have been made familiar with this disclosure that various changes in form and detail can be made without departing from the true scope of the invention in the appended claims.
Date Regue/Date Received 2022-08-12
In light of the state-of-the art, there exists a need for a new composition which can be used for the passivation of stainless steel which shows advantages not shared with conventional composition and methods associated therewith. The inventors have surprisingly and unexpectedly discovered a new acid composition and method to passivate metals using a composition which overcome some of the drawbacks of each one of the known and conventionally used passivation methods.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, there is provided a method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
Date Regue/Date Received 2022-08-12 for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
According to a preferred embodiment of the present invention, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1. Preferably, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no more than 15:1:1. According to another preferred embodiment of the present invention, said sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
Preferably, said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds. According to a preferred embodiment of the present invention, said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid;
tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethy1-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of CI-Cs linear alkyl and C1-05 branched alkyl. Preferably, said linear alkylaminosulfonic acid is selected form the group consisting of: methyl; ethyl (taurine); propyl; and butyl. Also preferably, said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl;
isobutyl; and isopentyl. More preferably, said compound comprising an amine moiety and a sulfonic acid moiety is taurine. According to a preferred embodiment of the present invention, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; butanesulfonic acid;
pentanesulfonic acid; hexanesulfonic acid; and combinations thereof.
According to a preferred embodiment of the present invention, said sulfuric acid and compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
According to another aspect of the present invention, there is provided a method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- an alkylsulfonic acid; and - a peroxide;
wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the Date Regue/Date Received 2022-08-12 composition.
Preferably, the method uses an aqueous acidic composition comprising:
- an alkylsulfonic acid; and - a peroxide; wherein said alkylsulfonic acid; and said peroxide are present in a molar ratio of no less than 1:1. Preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; butanesulfonic acid;
pentanesulfonic acid; hexanesulfonic acid; and combinations thereof. More preferably, said alkylsulfonic acid is methanesulfonic acid.
According to a preferred embodiment of the present invention, the method further comprises a compound comprising an amine moiety. Preferably, the compound comprising an amine moiety is a primary amine. More preferably, the compound comprising an amine moiety is an alkanolamine. More preferably, said alkanolamine is selected from the group consisting of:
monoethanolamine; diethanolamine;
triethanolamine; and combinations thereof.
According to a preferred embodiment of the present invention, the compound comprising an amine moiety is a tertiary amine. More preferably, said alkanolamine is triethanolamine.
According to an aspect of the present invention, there is provided a method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film, wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition. Preferably, the sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1:1:1.
sulfuric acid, said compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the compound comprising an amine moiety has a molecular weight below 300 g/mol.
According to a preferred embodiment of the present invention, the compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids and combinations thereof.
Preferably, said alkylsulfonic acid is selected from the group consisting of:
alkylsulfonic acids where the alkyl groups range from C1-C6 and are linear or branched; and combinations thereof.
DETAILED DESCRIPTION OF THE INVENTION
It will be appreciated that numerous specific details have been provided for a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered so that it may limit the scope of the embodiments described herein in any way, but rather as merely describing the implementation of the various embodiments described herein.
According to a preferred embodiment of the present invention, there is provided a method for the passivation of a steel surface, wherein said method comprises the steps of:
- providing said steel surface to be passivated;
- cleaning said steel surface to remove oil and other contaminants;
- exposing said steel surface to a modified Caro's acid for a period of time sufficient to form a layer of metal oxide thereon, wherein said modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and Date Regue/Date Received 2022-08-12 - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
According to a preferred embodiment of the present invention, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1. Preferably, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no more than 15:1:1. Preferably also, said sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
According to a preferred embodiment of the present invention, said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of:
taurine; taurine derivatives; and taurine-related compounds. Preferably, said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid;
tauromustine; 5-taurinomethyluridine and 5-taurinomethy1-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of CI-Cs linear alkyl and CI-Cs branched alkyl. Preferably, said linear alkylaminosulfonic acid is selected from the group consisting of: methyl; ethyl (taurine); propyl; and butyl. Preferably, said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl;
isobutyl; and isopentyl. Most preferably, said compound comprising an amine moiety and a sulfonic acid moiety is taurine.
According to a preferred embodiment of the present invention, said compound comprising an amine moiety is an alkanolamine is selected from the group consisting of:
monoethanolamine; diethanolamine;
triethanolamine; and combinations thereof.
According to a preferred embodiment of the present invention, said compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids and combinations thereof.
Date Regue/Date Received 2022-08-12 Preferably, said alkylsulfonic acid is selected from the group consisting of:
alkylsulfonic acids where the alkyl groups range from C1-C6 and are linear or branched; and combinations thereof. More preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid;
propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof. More preferably, said compound comprising a sulfonic acid moiety is methanesulfonic acid.
According to a preferred embodiment of the present invention, there is provided a method for the passivation of a steel surface, wherein said method comprises the steps of:
- providing said steel surface to be passivated;
- cleaning said steel surface to remove oil and other contaminants;
- exposing said steel surface to a modified Caro's acid for a period of time sufficient to form a layer of metal oxide thereon, wherein said modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, said alkylsulfonic acid; and said peroxide are present in a molar ratio of no less than 1:1.
According to a preferred embodiment of the present invention, in Composition C, said sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1:1:1.
According to a preferred embodiment of the present invention, in Composition C, said sulfuric acid, said compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is stainless steel.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a stainless steel selected from the group consisting of: Austenitic;
Martensitic-PH; Ferritic; Martensitic;
Austenitic-FM; Ferritic-FM; and Martensitic-FM.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Austenitic stainless steel, having a chromium content ranging from 15.0 to 23.5 %.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Austenitic stainless steel and is selected from the group consisting of:
Type 304/304L; Type 316/316L;
Type 305; Custom Flo 302HQ.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Martensitic-PH stainless steel having a chromium content ranging from 11.0 to 17.5 %.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Martensitic-PH stainless steel and is selected from the group consisting of: Custom 630 (17Cr-4Ni);
Custom 450; Custom 455; Custom 465T; and 15Cr-5Ni.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Martensitic stainless steel, having a chromium content of less than 15 %.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is Martensitic stainless steel and is selected from the group consisting of:
Type 410; Type 420; and TrimRite .
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic stainless steel having a chromium content above 16 %.
Preferably, said Ferritic stainless steel is type 430.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic stainless steel having a chromium content of less than 12 %.
Preferably, said Ferritic stainless steel is type 409.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Austenitic-FM stainless steel having a chromium content ranging from 17 to 19 %. Preferably, said Austenitic-FM stainless steel is type 303.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic-FM stainless steel having a chromium content above 16 %.
Preferably, said Ferritic-FM
stainless steel is selected from the group consisting of: type 430F; 430FR;
and Chrome Core 18-FM.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Ferritic-FM stainless steel having a chromium content of less than 13 %.
Preferably, said Ferritic-FM
stainless steel is type 409Cb-FM.
According to a preferred embodiment of the present invention, the metallic surface to be passivated is a Martensitic-FM stainless steel having a chromium content of less than 13 %. Preferably, said Martensitic-FM stainless steel is type 416.
Conventional nitric acid baths are changed when, upon titration, it is deemed that the solution is no longer capable of providing proper passivation. Another indicator used to decide whether to discard the acidic solution is by visual inspection and assessing the color of the bath.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the passivation bath using a modified Caro's acid, is able to process more metal than a conventional passivation bath. Moreover, it can extend its useful lifetime (i.e., period of time until the bath chemicals need to be discarded and replaced) by adding the peroxide component at intervals where the bath is known to start to lose its passivation efficiency.
Experiments to passivate various steels Various steel coupons were exposed to a composition comprising a modified Caro's acid as set out previously in order to assess the resulting passivated coupon's ability to withstand corrosion through acid exposure.
Corrosion of a Modified Caro's acid to treat Stainless Steel The purpose of this experiment is to test the corrosion rates of stainless steel in the presence of a modified Caro's acid and the corrosion rates of stainless steel after exposure to the delignification blend.
Procedure Corrosion tests were completed in glass sample jars in a heated water bath.
For each condition listed in Table 1, the coupon was washed with acetone, air dried, and weighed, before being suspended in the test fluid. The fluid in each glass sample jar was pre-heated to temperature before exposing the coupon to the acid blend. After the exposure period, the coupon was removed, washed with water, followed by an acetone wash, air dried, and then weighed. The corrosion rate was determined from the weight loss, and the pitting index (Appendix A) was evaluated visually at 40X magnification, and a photo of the coupon surface at 40X magnification was taken.
Table 1 lists the various compositions which were tested in the corrosion testing. The corrosion testing was carried out for a duration of 24 hours at a temperature of 30 C
(86 F) under atmospheric pressure.
Table 1: Listing of the compositions and coupons tested Test Coupon type Test fluid A 316SS 40 wt% sulfuric acid B-1 304SS Delignification blend C-1 316SS Delignification blend B-2 304SS 70 wt% sulfuric acid C-2 316SS 70 wt% sulfuric acid Date Regue/Date Received 2022-08-12 The corrosion test results are shown Table 2, and in Figure 1 to Figure 2.
Figure 1: Surface of 304SS coupon from corrosion test B-2 at 40X Magnification. Figure 2: Surface of 316SS coupon from corrosion test C-2 at 40X Magnification.
Table 2: Results of the corrosion testing of treated and untreated coupons at 30oC under atmospheric pressure for a duration of 24 hours Test Coupon # Corrosion rate Pitting index mm/year lb/ft2 A 325 40.756 0.180 9 B-1 19 0.014 0.000 0 C-1 310 0.000 0.000 0 B-2 19 0.002 0.000 0 C-2 310 0.007 0.000 0 Pitting index scale found in Finggar, M.; Jackson, J. Corrosion Science, 2014, 86, 17-41 Conclusion From the above experiments, it was found at the tested conditions that the modified Caro's acid composition was not corrosive to 304SS and 316SS (coupons B-1 and C-1).
Moreover, exposure of coupons B-1 and C-1 to a modified Caro's acid according to a preferred method of the present invention clearly passivated their surfaces. This is confirmed by subsequent exposure of those coupons to 70 wt% }12504, which resulted in an unblemished surface (as indicated by the photographs taken of the coupons now labelled B-2 and C-2.
Moreover, after the exposure to the modified Caro's acid, the steel coupons of 304SS and 316SS
were resistant to sulfuric acid corrosion at the tested conditions, whereas coupons not exposed to the modified Caro's acid were heavily corroded by sulfuric acid.
According to a preferred embodiment of the present invention, the compositions used for passivation of metals such as stainless steel can be reused be simply adding more peroxide. When used for passivating metals, the compositions consume the peroxide component and thus can be re-used a great number of times without losing effectiveness, as the consumable peroxide can be replenished by simply adding it to the used composition. This is a significant advantage over standard nitric acid and citric acid solutions, as they lose effectiveness over time and must be disposed of entirely.
Date Regue/Date Received 2022-08-12 According to a preferred embodiment of the present invention, the passivation method is employed to replace passivation by citric acid and treats metals used in a wide variety of industries, including but not limited to aerospace, medical, industrial and manufacturing industries.
While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be appreciated by those skilled in the relevant arts, once they have been made familiar with this disclosure that various changes in form and detail can be made without departing from the true scope of the invention in the appended claims.
Date Regue/Date Received 2022-08-12
Claims (33)
1. Method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
- providing said metallic surface;
- exposing said metallic surface to a modified Caro's acid composition selected from the group consisting of: composition A; composition B and Composition C;
wherein said composition A comprises:
- sulfuric acid in an amount ranging from 20 to 70 wt% of the total weight of the composition;
- a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and - a peroxide;
wherein said composition B comprises:
- an alkylsulfonic acid; and - a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt%
of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition;
wherein said composition C comprises:
- sulfuric acid;
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film created by the exposure of said metallic surface to said modified Caro's acid composition.
2. The method according to claim 1 wherein said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1.
3. The method according to claim 1 or 2, wherein said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no more than 15:1:1.
4. The method according to any one of claims 1 to 3, wherein sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
Date Regue/Date Received 2022-08-12
Date Regue/Date Received 2022-08-12
5. The method according to any one of claims 1 to 4, where said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of:
taurine; taurine derivatives; and taurine-related compounds.
taurine; taurine derivatives; and taurine-related compounds.
6. The method according to any one of claims 1 to 5, where said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid;
tauromustine; 5-taurinomethyluridine and 5-taurinomethy1-2-thiouridine;
homotaurine (tramiprosate);
acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of Ci-05 linear alkyl and C1-C 5 branched alkyl.
tauromustine; 5-taurinomethyluridine and 5-taurinomethy1-2-thiouridine;
homotaurine (tramiprosate);
acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of Ci-05 linear alkyl and C1-C 5 branched alkyl.
7. The method according to any one of claims 1 to 6, where said linear alkylaminosulfonic acid is selected form the group consisting of: methyl; ethyl (taurine); propyl; and butyl.
8. The method according to claim 7, where said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl; isobutyl; and isopentyl.
9. The method according to any one of claims 1 to 8, where said compound comprising an amine moiety and a sulfonic acid moiety is taurine.
10. The method according to any one of claims 1 to 9, wherein said sulfuric acid and compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.
11. Method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- an alkylsulfonic acid; and - a peroxide;
wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition.
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- an alkylsulfonic acid; and - a peroxide;
wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition.
12. The method according to claim 11 wherein said aqueous acidic composition comprises:
- an alkylsulfonic acid; and - a peroxide; wherein said alkylsulfonic acid; and said peroxide are present in a molar ratio of no less than 1:1.
Date Regue/Date Received 2022-08-12
- an alkylsulfonic acid; and - a peroxide; wherein said alkylsulfonic acid; and said peroxide are present in a molar ratio of no less than 1:1.
Date Regue/Date Received 2022-08-12
13. The method according to any one of claims 11 to 12 further comprising a compound comprising an amine moiety.
14. The method according to any one of claims 11 to 13, where said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid;
propanesulfonic acid; butanesulfonic acid; pentanesulfonic acid; hexanesulfonic acid; and combinations thereof.
propanesulfonic acid; butanesulfonic acid; pentanesulfonic acid; hexanesulfonic acid; and combinations thereof.
15 The method according to any one of claims 11 to 14, where said alkylsulfonic acid is methanesulfonic acid.
16. The method according to claim 13, wherein the compound comprising an amine moiety is a primary amine.
17. The method according to claim 16, wherein the compound comprising an amine moiety is an alkanolamine.
18. The method according to claim 16, wherein the compound comprising an amine moiety is a tertiary amine.
19. The method according to claim 17, wherein said alkanolamine is selected from the group consisting of: monoethanolamine; diethanolamine; triethanolamine; and combinations thereof.
20. The method according to claim 19, wherein said alkanolamine is tfiethanolamine.
21. Method for passivating a metallic surface, said method comprising:
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film, wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where Date Regue/Date Received 2022-08-12 the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition.
- providing said metallic surface;
- exposing said metallic surface to a composition comprising:
- a compound comprising an amine moiety;
- a compound comprising a sulfonic acid moiety; and - a peroxide;
for a period of time sufficient to coat said metallic surface with a metal oxide film, wherein the acid is present in an amount ranging from 40 to 80 wt% of the total weight of the composition and where Date Regue/Date Received 2022-08-12 the peroxide is present in an amount ranging from 10 to 40 wt% of the total weight of the composition.
22. The method according to claim 21, wherein sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1: 1: 1.
23. The method according to any one of claims 21 or 22, wherein sulfuric acid, said compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.
24. The method according to any one of claims 21 to 23, wherein said compound comprising an amine moiety has a molecular weight below 300 g/mol.
25. The method according to any one of claims 21 to 24, wherein where said compound comprising an amine moiety is a primary amine.
26. The method according to any one of claims 21 to 25, wherein said compound comprising an amine moiety is an alkanolamine.
27. The method according to any one of claims 21 to 26, wherein said compound comprising an amine moiety is a tertiary amine.
28. The method according to any one of claims 21 to 27, wherein said alkanolamine is selected from the group consisting of: monoethanolamine; diethanolamine; triethanolamine;
and combinations thereof.
and combinations thereof.
29. The method according to any one of claims 21 to 28, wherein said alkanolamine is triethanolamine.
30. The method according to any one of claims 21 to 29, wherein said compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids and combinations thereof.
31. The method according to any one of claims 21 to 30, wherein said alkylsulfonic acid is selected from the group consisting of: alkylsulfonic acids where the alkyl groups range from CI-C6 and are linear or branched; and combinations thereof.
Date Regue/Date Received 2022-08-12
Date Regue/Date Received 2022-08-12
32. The method according to claim 31, wherein said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; 2-propanesulfonic acid;
isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof.
isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof.
33. The method according to any one of claims 21 to 32, wherein said compound comprising a sulfonic acid moiety is methanesulfonic acid.
Date Regue/Date Received 2022-08-12
Date Regue/Date Received 2022-08-12
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA3170350A CA3170350A1 (en) | 2022-08-12 | 2022-08-12 | Method for passivating metal surfaces |
| PCT/CA2023/000018 WO2024031172A1 (en) | 2022-08-12 | 2023-08-10 | Method for passivating metal surfaces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA3170350A CA3170350A1 (en) | 2022-08-12 | 2022-08-12 | Method for passivating metal surfaces |
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ID=89834575
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| US7465408B1 (en) * | 2003-12-03 | 2008-12-16 | Advanced Micro Devices, Inc. | Solutions for controlled, selective etching of copper |
| GB2508827A (en) * | 2012-12-11 | 2014-06-18 | Henkel Ag & Co Kgaa | Aqueous compositions and processes for passivating and brightening stainless steel surfaces |
| CA3074198A1 (en) * | 2020-02-28 | 2021-08-28 | Fluid Energy Group Ltd. | Modified methanesulfonic acid and uses thereof |
| CA3102925A1 (en) * | 2020-12-18 | 2022-06-18 | Sixring Inc. | Novel approach to biomass delignification |
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