US1838777A - Chromium plating - Google Patents
Chromium plating Download PDFInfo
- Publication number
- US1838777A US1838777A US264952A US26495228A US1838777A US 1838777 A US1838777 A US 1838777A US 264952 A US264952 A US 264952A US 26495228 A US26495228 A US 26495228A US 1838777 A US1838777 A US 1838777A
- Authority
- US
- United States
- Prior art keywords
- chromium
- chloride
- bath
- per liter
- chromic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/04—Electroplating: Baths therefor from solutions of chromium
- C25D3/06—Electroplating: Baths therefor from solutions of chromium from solutions of trivalent chromium
Definitions
- chromium itself is largely if not wholly confined to chrome sulphates, chrome alums, and chromic acid baths.
- Our bath is founded on the use of chromic chloride and one or more, preferably the three, alkaline metal chlorides,potassium,
- sodium and ammonium chloride with or without other alkaline metal or earth salts such as sodium fluoride, potassium fluoride, ammonium fluoride, or barium, strontium, and calcium fluorides, chlorides, etc. salts raise. the conductivity of the bath and a given voltage will allow the passage of more current, 'thereby plating more rapidly and consequently efiecting economy in plant investment, supervision, etc.
- a reducing agent for reducing'the chromium compounds from higher states of oxidation to lower states of oxidation.
- this reducing agent is desirable in connection with these chromium anodes for the purpose of reducing the hexavalent form of chromium, such as the chromates, to the chromic stage, trivalent. This reduces the chromates into which compounds, among others, the anodes, dissolve to the same stage as the chromic salt with which the bath started, to wit: the chromic chloride.
- oxalic acid with hydrochloric acid is a suitable reducing agent for reducing the hexavalent chromium to the trivalent chromium.
- Hydrochloric acid in small amounts is always found in a bath of this kind, when chromium chloride is dissolved in water. This will serve to combine with the oxalic acid to reduce the hexavalent form of chromium to the trivalent form. This hexavalent form of chromium exists only when souble' chromium anodes are used. After the bath has These at the anodes.
- alkaline fluoride such as sodium fluoride is also effective in preventing the precipitation ofthe basic oxides of chromium on the cathode.
- Chromium chloride 300 grams per liter to saturation (cold) 300 grams per liter to saturation (cold), potassium chloride 250 grams per liter to saturation (cold), sodium chloride 250 grams per liter to saturation (cold), ammonium chloride 150 grams per liter tosaturation sodium fluoride 3 to 5 grams per liter oxalic acid 75 to 100 grams per liter cold), nitric acid 1%.
- nitric acid is desirable in preventing the formation'of the chromium oxide, and to act as a depolarizing agent
- chromium chloride in a crystalline form, that is, the hydrated chromic chloride which comes in the form of crystals and has the formula CrCl 6H O.
- cold cold cold chlorides in particular, is useful in eliminating the emission of noxious orpoisonous gases. This is especially true in avoiding the use of chromium sulphates, including a chromium alum bath.
- the reaction in such a bath results in the formation of chromic acid.
- chromic acid is formed in a bath of this kind, it reacts with the salts in the bath and free chlorine gas is given off at the anode.
- a process for chromium plating which comprises passing an electric current through a bath with a chromium anode and formed by dissolving in water chromic chloride and one or more of the alkaline metal and earth metal chlorides, and oxalic acid together with nitric acid.
- v An electro-plating bath in which chrmium chloride has been dissolved in water
Description
Patented Dec. 29, 1931 UNITED STATES A CORPORATION OF MICHIGAN PATENT OFFICE JOHN F. K; MGCULLOUGH AND BENJAMIN W. GILCHRIST, 0F TOETROIT, MICHIGAN,
ASSIGNOBS TO TERNSTED'I" MANUFACTURING COMPANY,
015 DETROIT, MICHIGAN,
ennomuirr marine electrolytic solution and electric current has 5 been proposed years ago. In the early nineties Messrs. Placet and Bonnet disclosed in several foreign and United States patents numerous solutions that were stated to pro-- duce good results. These disclosures are very 10 general. Numerous forms of chromium and other metals are stated in one or another of .these patents to be capable of use, and the.
chromium itself is largely if not wholly confined to chrome sulphates, chrome alums, and chromic acid baths.
Notwithstanding the variety and multiplicity of solutions, baths and acids, which had been stated in the Placet and Bonnet disclosures, practical chromium plating has only in the last few years become active, and thisactivity is now only in the pioneering stage. Great practical difliculty has been found, largely, due to the poor throwing capacity of chromium as compared to nickel and copper, it being found that unless conditions are absolutely right the high spots plate while some of the recesses have little or no coating of chromium. Within the last few years there has been a great deal of investigation and experimental work together with some practical plating, but so far as we are-advised, all these baths had been chromic acid (C10 baths. These baths are all founded onthe so-called Sargent solution, comprising a definite quantity of chromic acid and ;chromi um sulphate. This particular solution has been varied somewhat by the addition of other ingredients, 'and some stress has been placed in some recent patents upon the proper control of the bath, to wit: the'kn owledge of exactly how much of a catalyst is presentdisclosures of Placet and Bonnet concerning Application filed March 26, 1928.; Serial No. 264,952.
the catalyst content of the bath. This literature is here epitomized for the purpose of showing the prevailing practice and the care and nicety which is required in the proper operation of the chromic acid bath, thereby contrasting the wide departure from the pre- .vailing practice which has been accomplished by our bath.
Our bath is founded on the use of chromic chloride and one or more, preferably the three, alkaline metal chlorides,potassium,
sodium and ammonium chloride, with or without other alkaline metal or earth salts such as sodium fluoride, potassium fluoride, ammonium fluoride, or barium, strontium, and calcium fluorides, chlorides, etc. salts raise. the conductivity of the bath and a given voltage will allow the passage of more current, 'thereby plating more rapidly and consequently efiecting economy in plant investment, supervision, etc.
We find it desirable to use a reducing agent for reducing'the chromium compounds from higher states of oxidation to lower states of oxidation. We propose to preferably employ soluble chromium or chromium alloy anodes. We find that this reducing agent is desirable in connection with these chromium anodes for the purpose of reducing the hexavalent form of chromium, such as the chromates, to the chromic stage, trivalent. This reduces the chromates into which compounds, among others, the anodes, dissolve to the same stage as the chromic salt with which the bath started, to wit: the chromic chloride. We find that oxalic acid with hydrochloric acid is a suitable reducing agent for reducing the hexavalent chromium to the trivalent chromium.
Hydrochloric acid in small amounts is always found in a bath of this kind, when chromium chloride is dissolved in water. This will serve to combine with the oxalic acid to reduce the hexavalent form of chromium to the trivalent form. This hexavalent form of chromium exists only when souble' chromium anodes are used. After the bath has These at the anodes.
,It is therefore desirable to add from time to time amounts of hydrochloric acid and oxalic acid to the bath to reduce the hexavalent chromium in the-proportions that are given in the above equation.
We are aware that the use of oxalic acid has heretofore been 'propsed for use in the chromium bath, but it has been proposed for the purpose of acidulating the bath. The purpose of this acidulation is to dissolve the suboxides that are deposited on the cathode. So far as we are aware no acid has been introduced into a chromium bath which has a soluble chromium or chromium alloy anode for the purpose of acting as a reducing agent to reduce the chromates formed by the dissolution of the anode. Certainly no intelligent control and calculation of the bath with this end inview has heretofore been practiced.
We find that an alkaline fluoride such as sodium fluoride is also effective in preventing the precipitation ofthe basic oxides of chromium on the cathode.
The formula that we find very successful is: Chromium chloride (CrCl 6H O) 300 grams per liter to saturation (cold), potassium chloride 250 grams per liter to saturation (cold), sodium chloride 250 grams per liter to saturation (cold), ammonium chloride 150 grams per liter tosaturation sodium fluoride 3 to 5 grams per liter oxalic acid 75 to 100 grams per liter cold), nitric acid 1%.
We find that the nitric acid is desirable in preventing the formation'of the chromium oxide, and to act as a depolarizing agent,
I which facilitates the production of the chromium.
, We prefer to use chromium chloride in a crystalline form, that is, the hydrated chromic chloride which comes in the form of crystals and has the formula CrCl 6H O. We use the violet modification of this chromic chloride. It is our understanding that when chromic chloride is dissolved in water three different modifications .result, namely: Beta chromic chloride (Cr(H O)6) C1 violet; alpha chromic chloride I '(Cr(H O4Cl )Cl+2H O, green in color, and gamma chromic chloride (Cr(H O)5Cl )Cl+H O, also greenjn color. With the violet salt, the solution must be nearly neutral and' the temperature must rfnot be too high,from 80 to 140'degrees Fahrenheit. The acidity is regulated by the addition of caustic soda.-
With our bath we use a voltage of from 8 to 12, and a current density of from 250 to This reaction is as follows:
cold) cold chlorides, in particular, is useful in eliminating the emission of noxious orpoisonous gases. This is especially true in avoiding the use of chromium sulphates, including a chromium alum bath. The reaction in such a bath results in the formation of chromic acid. We find it desirable to eschew the joint use of -the alkaline chlorides and alkaline sulphates, or any combination of-the members of the two groups. These are bound to result in the production of chromic acid. Where chromic acid is formed in a bath of this kind, it reacts with the salts in the bath and free chlorine gas is given off at the anode.
' This is extremely poisonous. We also find that it is desirable to use a chromium or a soluble chromium alloy anode, even where only the chloride salts are used. Where insoluble anodes are used chlorine gas is released, which does not combine at the anode as is the case where a soluble chromium anode is used.
The voltage of 8 to 12, and the amperage of 250 to 1000 is stated at room temperature. It is of course well understood that when the temperature of the bath rises there will be a larger amperage d a smaller voltage. Therefore, when we state our limits of voltage and amperage in the claims, it is understood that this is a relative statement at room temperature, and that this is intended to cover other limits which would be automatically secured by varying the temperature of the a bath. It will be apparent that the current density is dependent upon several factors,- the cathode area, the temperature of the bath, the distance between electrodes, voltage,
in part and a substitute for application Serial No. 198,689, filed June 13, 1927; What we claim is:
1. A process for chromium plating which comprises passing an electric current through a bath with a chromium anode and formed by dissolving in water chromic chloride and one or more of the alkaline metal and earth metal chlorides, and oxalic acid together with nitric acid. v 2. An electro-plating bath in which chrmium chloride has been dissolved in water,
together with potassium chloride, sodium chloride and ammonium chloride, and substantially the proportions of 300 grams per liter to saturation of the chromium chloride,
250 grams per liter to saturation of the potas-. sium chloride, 250 grams per liter to saturation of the sodium chloride, and 150 grams per liter to saturation of the ammonium chloride,'together with 3 to 5 grams per liter of the sodium fluoride.
3. An electro-plating bath in which chromium chloride has been dissolved in water,
together with potassium chloride, sodium chloride and ammonium chloride, and substantially the proportions of 300 grams per liter to saturation of the chromium chloride, 250 grams per liter to saturation of the potassium chloride, 250 grams per liter to saturation of the sodium chloride, and 150 grams per liter to saturation of the ammonium chloride, together with substantially 3 to 5 grams sodium fluoride per liter, to grams oxalic acid, and 1%.nitric acid.
In testimony whereof we have afiixed our signatures. JOHN- F. K. MCCULLOUGH.
BENJAMIN W. GILCHRIST.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US264952A US1838777A (en) | 1928-03-26 | 1928-03-26 | Chromium plating |
GB13874/28A GB292094A (en) | 1928-03-26 | 1928-05-11 | Improvements in chromium plating |
FR655698D FR655698A (en) | 1928-03-26 | 1928-06-13 | Process for electroplating articles and products with chromium coating, and electrolyte used for this purpose |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US264952A US1838777A (en) | 1928-03-26 | 1928-03-26 | Chromium plating |
Publications (1)
Publication Number | Publication Date |
---|---|
US1838777A true US1838777A (en) | 1931-12-29 |
Family
ID=10030950
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US264952A Expired - Lifetime US1838777A (en) | 1928-03-26 | 1928-03-26 | Chromium plating |
Country Status (3)
Country | Link |
---|---|
US (1) | US1838777A (en) |
FR (1) | FR655698A (en) |
GB (1) | GB292094A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2415950A (en) * | 1943-02-08 | 1947-02-18 | Pittsburgh Plate Glass Co | Chromium compound |
US2733199A (en) * | 1956-01-31 | Electrolytic treatment of metal | ||
US2847371A (en) * | 1955-06-28 | 1958-08-12 | Tiarco Corp | Chromium plating on aluminum |
US4612091A (en) * | 1982-06-30 | 1986-09-16 | Asociation Pour La Recherche Et Le Developpement Des Methodes Et Processus Industriels | Chromium electroplating trivalent chrominum bath therefore and method of making such bath |
CN115976535A (en) * | 2022-12-23 | 2023-04-18 | 中国科学院青海盐湖研究所 | Method and device for preparing trivalent chromium salt by electrochemical oxidation of chromium iron in acid system |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2771414A (en) * | 1951-06-27 | 1956-11-20 | Reginald S Dean | Method of making electrolytic chromium |
DE1247803C2 (en) * | 1959-10-07 | 1973-03-29 | Du Pont | PROCESS FOR MANUFACTURING SELF-SUPPORTING METAL COMPOSITE FALMS BY DEPOSITING GALVANISCLES |
NL132271C (en) * | 1961-07-25 | |||
FR1563847A (en) * | 1968-01-30 | 1969-04-18 | ||
GB1437818A (en) * | 1973-05-31 | 1976-06-03 | British Chrome Chemicals Ltd | Electrodeposition of chromium |
CN103643251B (en) * | 2013-12-11 | 2015-11-18 | 中国科学院青海盐湖研究所 | Electrolytic process is utilized to prepare the method for potassium chromate solution |
-
1928
- 1928-03-26 US US264952A patent/US1838777A/en not_active Expired - Lifetime
- 1928-05-11 GB GB13874/28A patent/GB292094A/en not_active Expired
- 1928-06-13 FR FR655698D patent/FR655698A/en not_active Expired
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2733199A (en) * | 1956-01-31 | Electrolytic treatment of metal | ||
US2415950A (en) * | 1943-02-08 | 1947-02-18 | Pittsburgh Plate Glass Co | Chromium compound |
US2847371A (en) * | 1955-06-28 | 1958-08-12 | Tiarco Corp | Chromium plating on aluminum |
US4612091A (en) * | 1982-06-30 | 1986-09-16 | Asociation Pour La Recherche Et Le Developpement Des Methodes Et Processus Industriels | Chromium electroplating trivalent chrominum bath therefore and method of making such bath |
CN115976535A (en) * | 2022-12-23 | 2023-04-18 | 中国科学院青海盐湖研究所 | Method and device for preparing trivalent chromium salt by electrochemical oxidation of chromium iron in acid system |
CN115976535B (en) * | 2022-12-23 | 2023-08-18 | 中国科学院青海盐湖研究所 | Method and device for preparing trivalent chromium salt by electrochemical oxidation of ferrochrome in acidic system |
Also Published As
Publication number | Publication date |
---|---|
FR655698A (en) | 1929-04-22 |
GB292094A (en) | 1929-08-08 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US1838777A (en) | Chromium plating | |
US7780840B2 (en) | Process for plating chromium from a trivalent chromium plating bath | |
DE2447897A1 (en) | CHROME-CONTAINING GALVANIC BAEDER | |
DE852633C (en) | Process for the electrolytic deposition of dense, well-adhering copper coatings from baths | |
US2990343A (en) | Chromium alloy plating | |
DE587807C (en) | Process for the electrolytic deposition of palladium | |
US2704273A (en) | Process for chromium electrodeposition | |
US2408424A (en) | Pickling steels | |
US2728720A (en) | Method of producing an electroplate of nickel on magnesium and the magnesium-base alloys | |
US3649479A (en) | Process for chromium electroplating using electrolytic solutions containing trivalent chromium | |
GB954033A (en) | Improvements in or relating to electrodepositing chromium | |
US1544451A (en) | Electrodeposition of chromium | |
US1797357A (en) | Chromium plating | |
US2440715A (en) | Continuous method for electropolishing nickel and nickel-containing alloys | |
US3832292A (en) | Catalytic cathodic hardening of oxide films | |
US2182244A (en) | Chromium plating | |
DD211129B1 (en) | CIRCULAR PROCESS FOR COATING COPPER AND COPPER ALLOYS | |
US2131427A (en) | Process of electrolytically depositing iron and nickel alloy | |
USRE16598E (en) | Electrodeposition of chromium | |
US3390063A (en) | Electrolytes and method for anodizing aluminum | |
JPH01147100A (en) | Method for descaling cold rolled and annealed stainless steel strip | |
AT394398B (en) | METHOD FOR PROCESSING METAL CHLORIDE SOLUTIONS | |
SU132624A1 (en) | Method for electrochemical production of aluminum oxychlorides | |
CA1256357A (en) | Method of pickling iron or steel objects | |
US1948235A (en) | Electrolytic manufacture of iron and its alloys |