US2733199A - Electrolytic treatment of metal - Google Patents
Electrolytic treatment of metal Download PDFInfo
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- US2733199A US2733199A US2733199DA US2733199A US 2733199 A US2733199 A US 2733199A US 2733199D A US2733199D A US 2733199DA US 2733199 A US2733199 A US 2733199A
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- chromium
- metal
- boric acid
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- 229910052751 metal Inorganic materials 0.000 title claims description 82
- 239000002184 metal Substances 0.000 title claims description 82
- KRVSOGSZCMJSLX-UHFFFAOYSA-L Chromic acid Chemical compound O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 claims description 96
- 239000011651 chromium Substances 0.000 claims description 92
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 72
- 229910052804 chromium Inorganic materials 0.000 claims description 72
- KGBXLFKZBHKPEV-UHFFFAOYSA-N Boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 54
- 239000004327 boric acid Substances 0.000 claims description 52
- 239000000243 solution Substances 0.000 claims description 42
- ABXXWVKOBZHNNF-UHFFFAOYSA-N chromium(3+);dioxido(dioxo)chromium Chemical compound [Cr+3].[Cr+3].[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O ABXXWVKOBZHNNF-UHFFFAOYSA-N 0.000 claims description 24
- 239000010953 base metal Substances 0.000 claims description 22
- 239000011248 coating agent Substances 0.000 claims description 22
- 238000000576 coating method Methods 0.000 claims description 22
- 239000007864 aqueous solution Substances 0.000 claims description 20
- 150000001875 compounds Chemical class 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 14
- 235000010338 boric acid Nutrition 0.000 description 50
- 239000003973 paint Substances 0.000 description 22
- 230000015572 biosynthetic process Effects 0.000 description 16
- 238000005755 formation reaction Methods 0.000 description 16
- PEDCQBHIVMGVHV-UHFFFAOYSA-N glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 16
- 235000011187 glycerol Nutrition 0.000 description 16
- 150000003839 salts Chemical class 0.000 description 16
- 239000011780 sodium chloride Substances 0.000 description 16
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 14
- 238000005260 corrosion Methods 0.000 description 14
- 239000003792 electrolyte Substances 0.000 description 14
- 230000001603 reducing Effects 0.000 description 14
- HCHKCACWOHOZIP-UHFFFAOYSA-N zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 14
- 229910052725 zinc Inorganic materials 0.000 description 14
- 239000011701 zinc Substances 0.000 description 14
- 229910000831 Steel Inorganic materials 0.000 description 10
- 238000005868 electrolysis reaction Methods 0.000 description 10
- 150000002739 metals Chemical class 0.000 description 10
- 239000010959 steel Substances 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000001681 protective Effects 0.000 description 8
- 230000002829 reduced Effects 0.000 description 8
- 239000003795 chemical substances by application Substances 0.000 description 6
- -1 for example Chemical compound 0.000 description 6
- 229910052718 tin Inorganic materials 0.000 description 6
- ATJFFYVFTNAWJD-UHFFFAOYSA-N tin hydride Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 6
- QDOXWKRWXJOMAK-UHFFFAOYSA-N Chromium(III) oxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 4
- 231100000078 corrosive Toxicity 0.000 description 4
- 231100001010 corrosive Toxicity 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000011368 organic material Substances 0.000 description 4
- 239000011253 protective coating Substances 0.000 description 4
- XNLICIUVMPYHGG-UHFFFAOYSA-N 2-Pentanone Chemical compound CCCC(C)=O XNLICIUVMPYHGG-UHFFFAOYSA-N 0.000 description 2
- CZMRCDWAGMRECN-UGDNZRGBSA-N D-sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 2
- 229940021013 Electrolyte solutions Drugs 0.000 description 2
- 210000002370 ICC Anatomy 0.000 description 2
- KDZKNBQPACSGKP-UHFFFAOYSA-L OB(O)O.O[Cr](O)(=O)=O Chemical compound OB(O)O.O[Cr](O)(=O)=O KDZKNBQPACSGKP-UHFFFAOYSA-L 0.000 description 2
- CZMRCDWAGMRECN-GDQSFJPYSA-N Sucrose Natural products O([C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@H](CO)O1)[C@@]1(CO)[C@H](O)[C@@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-GDQSFJPYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000001464 adherent Effects 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- NGKQNTOXCAGWRY-UHFFFAOYSA-N bis(dioxidoboranyloxy)borinate Chemical compound [O-]B([O-])OB([O-])OB([O-])[O-] NGKQNTOXCAGWRY-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 2
- 229910052793 cadmium Inorganic materials 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 230000003197 catalytic Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- GRWVQDDAKZFPFI-UHFFFAOYSA-H chromium(III) sulfate Chemical compound [Cr+3].[Cr+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRWVQDDAKZFPFI-UHFFFAOYSA-H 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- LVSJLTMNAQBTPE-UHFFFAOYSA-N disodium tetraborate Chemical compound [Na+].[Na+].O1B(O)O[B-]2(O)OB(O)O[B-]1(O)O2 LVSJLTMNAQBTPE-UHFFFAOYSA-N 0.000 description 2
- KRHIGIYZRJWEGL-UHFFFAOYSA-N dodecapotassium;tetraborate Chemical compound [K+].[K+].[K+].[K+].[K+].[K+].[K+].[K+].[K+].[K+].[K+].[K+].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-] KRHIGIYZRJWEGL-UHFFFAOYSA-N 0.000 description 2
- 238000005323 electroforming Methods 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 230000002708 enhancing Effects 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 235000019441 ethanol Nutrition 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- 230000036961 partial Effects 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 2
- 230000001737 promoting Effects 0.000 description 2
- 239000003638 reducing agent Substances 0.000 description 2
- 235000010339 sodium tetraborate Nutrition 0.000 description 2
- 239000004328 sodium tetraborate Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000005720 sucrose Substances 0.000 description 2
- 239000011135 tin Substances 0.000 description 2
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/38—Chromatising
Definitions
- This invention relates to the protective treatment of metal surfaces, and more particularly to the cathodic treatment of metal surfaces, such as those of iron, steel, zinc, or other base metals, in a solution containing trivalent and hexavalent chromium alongwith boric acid or salts of boric acid.
- the principal object of this invention is to develop an improved paint adhering film on the surface of base metals such as iron, steel and zinc.
- Another object is to inhibit underfilm corrosion in painted metal articles.
- a further object is to form a protective film on articles having base metal surfaces.
- Another object is to increase the efficiency of formation of chromium-containing colloidal films on metal.
- paint-bonding films have been found to have sufficient anti-corrosive properties in mildly corrosive atmospheres, so that the film itself may assume the nature of a protective coating on metal. Even when steel or other basis stock is coated with one of the so-called protective coating metals, as tin or zinc, it is oftentimes desirable to further coat the surface with a non-metallic film, other than paint, to prevent incipient corrosion.
- a chromic acid-boric acid electrolyte said electrolyte being substantially free of chromium sulfate if part of the hexavalent chromium, present as chromic acid, is reduced to trivalent chromium, prior to electrolysis, rate of film formation is increased by a considerable amount,- and the resultant film has improved corrosion resistance over films formed from electrolyte solutions of chromic and boric acids alone.
- Reduction of the hexavalent chromium may be obtained by adding to the electrolyte, prior to electrolysis, an organic material capable of being oxidized by the hexavalent chromium, for example, glycerine.
- the film formed by my invention is colloidal in nature and is believed to consist of a hydrated oxide of chromium.
- This hydrated oxide contains both hexavalent and trivalent nited States Patent ICC chromium, some of the Cr having been reduced in the bath to Cr
- the amount of Cr present in the bath is controlled by the amount of reducing material added.
- the composition of chromium chromate is variable, but for practical purposes may be taken to be Cr(HCrO4)3.
- the chromic acid not thus combined as chromium chromate is present as free chromic acid. It is preferable that not more than of the original chromic acid be acted upon by the organic reducing material, thus at least 25% of the original chromic acid remains in the bath as free chromic acid. As the amount of trivalent chromium in the bath is increased through reduction of the hexavalent chromium, the amount of boric acid present may be correspondingly reduced.
- Boric acid which has a catalytic action in promoting the desired film formation, may be replaced in the bath by salts of boric acid such as sodium tetraborate, calcium metaborate and potassium tetraborate, the salts of the acid having an equivalence of function to that of boric acid.
- boric acid such as sodium tetraborate, calcium metaborate and potassium tetraborate
- any other suitable organic agent may be used in developing formation of trivalent chromium which does not tend to form undesirable by-products in solution.
- organic agents capable of efficiently reducing chromium from the hexavalent to the trivalent state are sucrose, ethyl alcohol and acetone.
- the presence of trivalent chromium in the electrolytic bath apparently has an accelerating action on the rate of film formation, and the ratio of Cr" to Cr in the film is such that superior corrosion properties are developed when the coating is used as an under-paint film, or when used alone in mildly corrosive atmospheres.
- the method of using an organic material ito reduce hexavalent chromium is the preferred one in securing the proper amount of trivalent chromium in solution, prior to electrolyzing; however, my invention is not restricted to this particular aspect, for trivalent chromium i metals by my method is obtained under a wide range of operating conditions.
- chromic acid when corrodible ferrous metals, or metals having a surface coating of a corrodible base metal such as zinc, are treated cathodically With direct current in a bath of chromic acid, boric acid and some trivalent chromium (formed by partial reduction of chromic acid), the original addition of chromic acid, calculated as CrOs, may range from 100 to 400 grams per liter, and the boric acid, or salts of boric acid, may be present in quantities of from 8 grams per liter to saturation.
- the amount of glycerine, or other organic reducing agent added is determined empirically and is governed by the amount of trivalent chromium one desires to form in the bath, as well as by the nature of the reducting agent itself.
- My method of producing a hydrated oxide of chromium film on metal surfaces is particularly advantageous where numerous large sheets must be processed, for the formation of trivalent chromium in the bath prior to electrolyzing increases the efiiciency of the treatment by as much as 100% over any previously known method for the production of a similar type of chromium bearing colloidal film. Besides, as has been mentioned, increased corrosion resistance characteristics are obtained.
- base metals I mean to include all metals which corrode readily, as distinguished from the noble metals and the non-corrodible alloys such as stainless steel.
- the process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a metal article having a surface material of corrodible base metal in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), a compound of the class consisting of boric acid and salts of boric acid, said compound being present in an amount of from 8 grams per liter to saturation, and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
- the process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a metal article having a surface material of corrodible base metal in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), boric acid (8 grams per liter to saturation) and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
- the process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a metal article having a surface material of corrodible base metal in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), boric acid (8 grams per liter to saturation) and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode, at a current density of from to 300 amperes per square foot for not less than 10 seconds.
Description
ELECTROLYTIC TREATMENT OF METAL SURFACES Richard M. Wick, Allentown, Pa., assignor to Bethlehem Steel Company, a corporation of Pennsylvania No Drawing. Application July 20, 1951,
Serial No. 237,849
7 Claims. (Cl. 204-56) This invention relates to the protective treatment of metal surfaces, and more particularly to the cathodic treatment of metal surfaces, such as those of iron, steel, zinc, or other base metals, in a solution containing trivalent and hexavalent chromium alongwith boric acid or salts of boric acid.
The principal object of this invention is to develop an improved paint adhering film on the surface of base metals such as iron, steel and zinc.
Another object is to inhibit underfilm corrosion in painted metal articles.
A further object is to form a protective film on articles having base metal surfaces.
Another object is to increase the efficiency of formation of chromium-containing colloidal films on metal.
It is often desirable, before painting metal surfaces, to apply a thin intermediate film to a metal surface, such that when paint is later applied there will be an adherent bond between the paint and the metal. Frequently, when paint is applied directly to a metal surface, the paint will strip, peel or chip after short periods of wear or exposure. To enhance the adherence of paint to metal, numerous metal surface films have been developed, notably films containing phosphates, which retain the paint uniformly throughout the surface of the metal. These intermediate, paint-bonding films, are generally applied to the metal by immersion or electrolysis in aqueous solutions.
Some paint-bonding films have been found to have sufficient anti-corrosive properties in mildly corrosive atmospheres, so that the film itself may assume the nature of a protective coating on metal. Even when steel or other basis stock is coated with one of the so-called protective coating metals, as tin or zinc, it is oftentimes desirable to further coat the surface with a non-metallic film, other than paint, to prevent incipient corrosion.
In the production of films on metals by means of cathodic electrolysis from solutions containing chromium, attempts have been made at film formation from solutions containing chromic acid (C103) alone. The films obtained are thin, non-uniform and inadequate from the standpoint of corrosion resistance. Very good films have been produced by cathodic electrolysis from solutions containing both chromic acid and boric acid.
I have found that when using a chromic acid-boric acid electrolyte, said electrolyte being substantially free of chromium sulfate if part of the hexavalent chromium, present as chromic acid, is reduced to trivalent chromium, prior to electrolysis, rate of film formation is increased by a considerable amount,- and the resultant film has improved corrosion resistance over films formed from electrolyte solutions of chromic and boric acids alone. Reduction of the hexavalent chromium may be obtained by adding to the electrolyte, prior to electrolysis, an organic material capable of being oxidized by the hexavalent chromium, for example, glycerine. The film formed by my invention is colloidal in nature and is believed to consist of a hydrated oxide of chromium. This hydrated oxide contains both hexavalent and trivalent nited States Patent ICC chromium, some of the Cr having been reduced in the bath to Cr The amount of Cr present in the bath is controlled by the amount of reducing material added. By this easy and practical method of control, good results are obtained with formation in the bath of trivalent chromium in amounts up to approximately 18% based on total chromium in solution. When, in the presence of chromic acid, trivalent chromium is formed in solution, it associates with a part of the remaining chromic acid to form a chromium chromate. The composition of chromium chromate is variable, but for practical purposes may be taken to be Cr(HCrO4)3. The chromic acid not thus combined as chromium chromate is present as free chromic acid. It is preferable that not more than of the original chromic acid be acted upon by the organic reducing material, thus at least 25% of the original chromic acid remains in the bath as free chromic acid. As the amount of trivalent chromium in the bath is increased through reduction of the hexavalent chromium, the amount of boric acid present may be correspondingly reduced. Boric acid, which has a catalytic action in promoting the desired film formation, may be replaced in the bath by salts of boric acid such as sodium tetraborate, calcium metaborate and potassium tetraborate, the salts of the acid having an equivalence of function to that of boric acid. In place of glycerine, any other suitable organic agent may be used in developing formation of trivalent chromium which does not tend to form undesirable by-products in solution. Examples of organic agents capable of efficiently reducing chromium from the hexavalent to the trivalent state are sucrose, ethyl alcohol and acetone. The presence of trivalent chromium in the electrolytic bath apparently has an accelerating action on the rate of film formation, and the ratio of Cr" to Cr in the film is such that superior corrosion properties are developed when the coating is used as an under-paint film, or when used alone in mildly corrosive atmospheres.
As one example of the manner in which a reduced chromium bath may be prepared, I formed an aqueous solution of the following ingredients:
G./l. Chromic acid (CrOs) 295 Boric acid (HsBOs) 20 Glycerine 7.5
As there is some heat evolved during the reaction, the materials were added slowly to prevent loss, and upon cooling to room temperature the solution was ready for use as an electrolytic coating bath. At this point some of the hexavalent chromium had been converted to trivalent chromium by the reducing action of the glycerine. A test of the solution indicated that 18.5 grams per liter of Cr were now present in the solution. It should be noted that the Cr produced in this example is well within the recommended limit of 18% of the total chromium in solution.
The method of using an organic material ito reduce hexavalent chromium is the preferred one in securing the proper amount of trivalent chromium in solution, prior to electrolyzing; however, my invention is not restricted to this particular aspect, for trivalent chromium i metals by my method is obtained under a wide range of operating conditions. For example, when corrodible ferrous metals, or metals having a surface coating of a corrodible base metal such as zinc, are treated cathodically With direct current in a bath of chromic acid, boric acid and some trivalent chromium (formed by partial reduction of chromic acid), the original addition of chromic acid, calculated as CrOs, may range from 100 to 400 grams per liter, and the boric acid, or salts of boric acid, may be present in quantities of from 8 grams per liter to saturation. The amount of glycerine, or other organic reducing agent added is determined empirically and is governed by the amount of trivalent chromium one desires to form in the bath, as well as by the nature of the reducting agent itself. Within the range given above for CrOs, i. e., 100 to 400 grams per liter, it is permissible to form trivalent chromium in the bath in quantities ranging from 5 to approximately 40 grams per liter. Satisfactory temperatures were found to be included in the range from 20 C. to 45 C., while the current density may be applied within the limits of 50 to 300 amperes per square foot. The time of treatment is controlled by the type of film desired; i. e., whether the film is to be used for improvement in paint adhesion and inhibition of under film (paint film) corrosion, or as a protective film per se. When a protective film is desired, a greater film thickness is required, hence a longer electrolyizing period is necessary, as may be determined by test.
An example of a satisfactory aqueous electrolyte with normal operating conditions is given below.
Chromic acid (CrOs) g./l 275 Boric acid (I-IzBOa) g./l 20 Cr produced by addition of glycerine g./l 18 Current density amp./sq.ft. 200 Temperature /C 24 Time seconds 13 The above bath represents a cooled electrolyte ready for use, prepared, as previously described, by the slow addition of glycerine to a solution of chromic acid and boric acid. The glycerine converts part of the Cr" to nr As there will be some depletion of the electrolyte during use, the electrolyte should be tested from time to time so that additions can be made and a properly balanced bath maintained.
The above-mentioned bath, under the operating conditions given therewith, was used in a series of actual tests, and it produced an excellent chromium chromate film on electrolytic zinc-plated steel sheet and an blackplate.
My method of producing a hydrated oxide of chromium film on metal surfaces, such as steel (blackplate), zinccoated sheets, or other base metal surfaces, is particularly advantageous where numerous large sheets must be processed, for the formation of trivalent chromium in the bath prior to electrolyzing increases the efiiciency of the treatment by as much as 100% over any previously known method for the production of a similar type of chromium bearing colloidal film. Besides, as has been mentioned, increased corrosion resistance characteristics are obtained.
My method of treatment can be successfully applied to any base metal, and it has particular utility in respect to zinc, tin, magnesium, cadmium and the corrodible ferrous metals. By base metals I mean to include all metals which corrode readily, as distinguished from the noble metals and the non-corrodible alloys such as stainless steel.
I claim:
1. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a metal article having a surface material of corrodible base metal in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), a compound of the class consisting of boric acid and salts of boric acid, said compound being present in an amount of from 8 grams per liter to saturation, and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
2. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a zinc-coated article in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), a compound of the class consisting of boric acid and salts of boric acid, said compound being present in an amount of from 8 grams per liter to saturation, and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
3. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a corrodible ferrous article in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), a compound of the class consisting of boric acid and salts of boric acid, said compound being present in an amount of from 8 grams per liter to saturation, and chromium chromate in which the trivalent chrominm is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal xt'icle acting as the cathode.
4. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a tin-coated article in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), a compound of the class consisting of boric acid and salts of boric acid, said compound being present in an amount of from 8 grams per liter to saturation, and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
5. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a metal article having a surface material of corrodible base metal in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), boric acid (8 grams per liter to saturation) and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
6. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a zinc-coated article in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter),
' boric acid (10 grams per liter to saturation) and chromium chromate in which the trivalent chromium is pres ent in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode.
7. The process of forming a non-metallic coating on the surface of a metal article which comprises electrolyzing a metal article having a surface material of corrodible base metal in an aqueous solution consisting essentially of chromic acid (100 to 400 grams per liter), boric acid (8 grams per liter to saturation) and chromium chromate in which the trivalent chromium is present in an amount between 2 per cent and 18 per cent of the total chromium in solution, said metal article acting as the cathode, at a current density of from to 300 amperes per square foot for not less than 10 seconds.
References Cited in the file of this patent UNITED STATES PATENTS 1,827,247 Mason Oct. 13, 1931 1,838,777 McCullough ct a1 Dec. 29, 1931 1,853,323 Schulein Apr. 12, 1932 2,063,197 Sehneidewind Dec. 8, 1936 2,635,993 Snavcly Apr. 21, 1953 FOREIGN PATENTS 254,757 Great Britain Oct. 6, 1927 OTHER REFERENCES Principles of Electroplating and Electroforming, by Blum et al., second edition (1930), page 293. t
Claims (1)
1. THE PROCESS OF FORMING A NON-METALLIC COATING ON THE SURFACES OF A METAL ARTICLE WHICH COMPRISES ELECTROLYZING A METAL ARTICLE HAVING A SURFACE MATERIAL OF CORRODIBLE BASE METAL IN AN AQUEOUS SOLUTION CONSISTING ESSENTIALLY OF CHROMIC ACID (100 TO 400 GRAMS PER LITER), A COMPOUND OF THE CLASS CONSISTING OF BORIC ACID AND SALTS OF BORIC ACID, SAID COMPOUND BEING PRESENT IN AN AMOUNT OF FROM 8 GRAMS PER LITER TO SATURATION, AND CHROMIUM CHROMATE IN WHICH THE TRIVALENT CHROMIUM IS PRESENT IN AN AMOUNT BETWEEN 2 PER CENT AND 18 PER CENT OF THE TOTAL CHROMIUM IN SOLUTION, SAID METAL ARTICLE ACTING AS THE CATHODE.
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| Publication Number | Publication Date |
|---|---|
| US2733199A true US2733199A (en) | 1956-01-31 |
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| US2733199D Expired - Lifetime US2733199A (en) | Electrolytic treatment of metal |
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3032487A (en) * | 1958-05-30 | 1962-05-01 | Yawata Iron & Steel Co | Electrolytic treatment of ferrous metal surfaces |
| US3081238A (en) * | 1958-09-03 | 1963-03-12 | Quaker Chem Corp | Electrolytic treatment of metal surfaces |
| US3257295A (en) * | 1962-01-20 | 1966-06-21 | Yawata Iron & Steel Co | Method of chemically treating metals |
| US3278401A (en) * | 1966-01-12 | 1966-10-11 | Nat Steel Corp | Method of treating tin-containing surfaces |
| US3296106A (en) * | 1966-01-12 | 1967-01-03 | Nat Steel Corp | Method of cathodically treating metallic surfaces |
| DE1236898B (en) * | 1962-11-10 | 1967-03-16 | Toyo Kohan Co Ltd | Process for the electrochemical production of protective coatings on metals |
| US3342710A (en) * | 1962-07-27 | 1967-09-19 | Ngk Insulators Ltd | Method of rust proofing treatment of metals |
| DE1291595B (en) * | 1960-01-23 | 1969-03-27 | Yawata Iron & Steel Co | Process for the cathodic surface treatment of metal objects |
| DE1621076B1 (en) * | 1966-03-26 | 1971-08-26 | Fuji Iron & Steel Co Ltd | PROCESS FOR THE ELECTROLYTIC PRODUCTION OF A CHROMATE COATING ON GALVANIC CHROMED STEEL |
| US4094750A (en) * | 1977-10-05 | 1978-06-13 | Northrop Corporation | Cathodic deposition of oxide coatings |
| US4137132A (en) * | 1976-06-01 | 1979-01-30 | Bnf Metals Technology Centre | Chromite coatings, electrolytes, and electrolytic method of forming the coatings |
| US4350574A (en) * | 1981-03-23 | 1982-09-21 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Method for depositing an oxide coating |
| EP0224065A1 (en) * | 1985-11-01 | 1987-06-03 | Nihon Parkerizing Co., Ltd. | Process for obtaining chromate layers |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB254757A (en) * | 1925-07-06 | 1927-10-06 | Gen Motors Corp | Improvement in and relating to electrolytic deposition of chromium |
| US1827247A (en) * | 1927-10-18 | 1931-10-13 | Western Electric Co | Method of protecting metal surfaces |
| US1838777A (en) * | 1928-03-26 | 1931-12-29 | Ternstedt Mfg Co | Chromium plating |
| US1853323A (en) * | 1928-09-24 | 1932-04-12 | Schulein Joseph | Colored coating and process for producing the same |
| US2063197A (en) * | 1933-08-30 | 1936-12-08 | Schneidewind Richard | Method of chromium plating |
| US2635993A (en) * | 1948-10-16 | 1953-04-21 | Battelle Development Corp | Electrolytic production of chromium hydride |
-
0
- US US2733199D patent/US2733199A/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB254757A (en) * | 1925-07-06 | 1927-10-06 | Gen Motors Corp | Improvement in and relating to electrolytic deposition of chromium |
| US1827247A (en) * | 1927-10-18 | 1931-10-13 | Western Electric Co | Method of protecting metal surfaces |
| US1838777A (en) * | 1928-03-26 | 1931-12-29 | Ternstedt Mfg Co | Chromium plating |
| US1853323A (en) * | 1928-09-24 | 1932-04-12 | Schulein Joseph | Colored coating and process for producing the same |
| US2063197A (en) * | 1933-08-30 | 1936-12-08 | Schneidewind Richard | Method of chromium plating |
| US2635993A (en) * | 1948-10-16 | 1953-04-21 | Battelle Development Corp | Electrolytic production of chromium hydride |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3032487A (en) * | 1958-05-30 | 1962-05-01 | Yawata Iron & Steel Co | Electrolytic treatment of ferrous metal surfaces |
| DE1228118B (en) * | 1958-05-30 | 1966-11-03 | Yawata Seitetsu Kabushiki Kais | Process for the cathodic surface treatment of iron and steel objects |
| US3081238A (en) * | 1958-09-03 | 1963-03-12 | Quaker Chem Corp | Electrolytic treatment of metal surfaces |
| DE1291595B (en) * | 1960-01-23 | 1969-03-27 | Yawata Iron & Steel Co | Process for the cathodic surface treatment of metal objects |
| US3257295A (en) * | 1962-01-20 | 1966-06-21 | Yawata Iron & Steel Co | Method of chemically treating metals |
| US3342710A (en) * | 1962-07-27 | 1967-09-19 | Ngk Insulators Ltd | Method of rust proofing treatment of metals |
| DE1236898B (en) * | 1962-11-10 | 1967-03-16 | Toyo Kohan Co Ltd | Process for the electrochemical production of protective coatings on metals |
| US3337431A (en) * | 1962-11-10 | 1967-08-22 | Toyo Kohan Co Ltd | Electrochemical treatment of metal surfaces |
| US3296106A (en) * | 1966-01-12 | 1967-01-03 | Nat Steel Corp | Method of cathodically treating metallic surfaces |
| US3278401A (en) * | 1966-01-12 | 1966-10-11 | Nat Steel Corp | Method of treating tin-containing surfaces |
| DE1621076B1 (en) * | 1966-03-26 | 1971-08-26 | Fuji Iron & Steel Co Ltd | PROCESS FOR THE ELECTROLYTIC PRODUCTION OF A CHROMATE COATING ON GALVANIC CHROMED STEEL |
| US4137132A (en) * | 1976-06-01 | 1979-01-30 | Bnf Metals Technology Centre | Chromite coatings, electrolytes, and electrolytic method of forming the coatings |
| US4094750A (en) * | 1977-10-05 | 1978-06-13 | Northrop Corporation | Cathodic deposition of oxide coatings |
| US4350574A (en) * | 1981-03-23 | 1982-09-21 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Method for depositing an oxide coating |
| EP0224065A1 (en) * | 1985-11-01 | 1987-06-03 | Nihon Parkerizing Co., Ltd. | Process for obtaining chromate layers |
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