US2096309A - Surface treatment of aluminum and aluminum alloys - Google Patents
Surface treatment of aluminum and aluminum alloys Download PDFInfo
- Publication number
- US2096309A US2096309A US52932A US5293235A US2096309A US 2096309 A US2096309 A US 2096309A US 52932 A US52932 A US 52932A US 5293235 A US5293235 A US 5293235A US 2096309 A US2096309 A US 2096309A
- Authority
- US
- United States
- Prior art keywords
- aluminum
- treatment
- sodium
- weight
- per cent
- 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
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/18—Polishing of light metals
- C25F3/20—Polishing of light metals of aluminium
-
- 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
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
Definitions
- This invention relates to the surface treatment of aluminum and aluminum alloys and more particularly to treatment directed to the improvement of the specular reflectivity of such surfaces.
- Sheet aluminum as produced by the normal rolling process has an average specular reflectivity for light of about 65 per cent.
- the reflectivity may be increased by processes such as polishing up to a figure of 75 per cent. to 80 per cent.'but on exposure to air this enhanced reflecting power decreases rapidly until a figure equivalent to that for normal rolled sheet is reached.
- the object of the present invention is the provision of a method and means by which the specular reflectivity of an aluminum or aluminum alloy surface may be increased very considerably in a cheap, eflicient and permanent manner.
- the present invention consists in a process for increasing the specular reflectivity of the surface of an aluminum or aluminum alloy article which comprises immersing the previously degreased article in an aqueous solution of sodium carbonate and tri-sodium orthophosphate to remove the normal oxide film, then immediately thereafter in the same solution subjecting the article to anodic treatment by direct current at a moderately high current density for a short time to stop the attack of the solution upon the article and continuing the anodic treatment by direct current at a lower current density, and, after washing in water, subjecting the article to further electrolytic treatment in a strong aqueous solution of sodium bisulphate.
- a piece of commercially pure rolled aluminum sheet is first degreased by suitable means such as cleaning in petrol, then, if necessary, it is buffed or otherwise polished mechanically. It is then given a. chemico-electrical treatment in a bath having the following composition and under the following conditions.
- the cathode is made to conform roughly to the anodic surface.
- the metal is again subjected to an anodic process in another electrolyte, the composition of which and the conditions of operation being as follows Electrolyte Aqueous solution containing 25 per cent. by weight of sodium bisulphate.
- the current density is of the order of 5 amperes per square foot.
- the composition of the electrolyte may include all strong alkaline electrolytes having a pH value of over 10, containing an ortho-phosphoric acid radicle corresponding in quantity to that contained in approximately 3 to 9 per cent, by weight of trisodium ortho-phosphate, and with akalinities due to the hydroxides or carbonates of the alkali metals such as sodium, potassium, lithium, with or without the addition of alkali metal salts such as, for instance, borates or chromates.
- the temperature range of the electrolyte may extend from about 40 to about 100 C.
- the applied voltage may be varied between limits of about 2 to about 20 volts.
- direct current is to be used, which term is intended to include unidirectional current of any kind..
- the electrolyte may comprise, in addition to the aqueous solution of sodium bisulphate, aqueous solutions of such substances as sulphuric acid, chromium sulphate, chromium oxalate, chromic acid, boric acid, phosphoric acid, acetic acid or salts of such acids.
- the percentage of sodium bisulphate may be from 5 to 40 per cent. by weight, the temperature may be from 20-50 C. and the voltage from about 5 to about 30 volts.
- the current may be of a direct or alternating character.
- the film, presumably of aluminum oxide, produced by the second part of the process hereinbefore described, viz. the protective coating for the brightened surface is relatively hard but is quite transparent and differs from similar oxide films formed in other, e. g., sulphuric acid or oxalic acid, electrolytes in that it does not reduce the reflectivity value of the film produced in the first part of the process, in fact, in many instances it has been found that the reflectivity value has been slightly raised.
- the process according to the invention is applicable to all kinds of surfaces either normal, polished or mat and in all cases results in a considerable increase of the specular reflectivity of the original material.
- a process for improving the reflectivity of the surface of a clean aluminum or aluminum alloy surface which comprises immersing the surface for a short time in an aqueous solution of sodium carbonate and tri-sodium orthophosphate in the proportions of about 3 parts by weight of the carbonate to about 1 part by weight of the phosphate and having a pH value of 10 or more and a temperature of about to C., and then without removing the surface from the solution applying direct current anodic treatment thereto.
- a process for improving the reflectivity of the surface of a clean aluminum or aluminum alloy surface which comprises immersing the surface for a short time in an aqueous solution of sodium carbonate and tri-sodium orthophosphate in the proportions of about 3 parts by weight of the carbonate to about 1 part by weight of the phosphate and having a pH value of 10 or more and a temperature of about 75 to 85 C., then washing the surface and providing a protective coating therefor by anodic treatment in an aqueous solution of sodium bisulphate.
- a process for improving the reflectivity of the surface of a clean aluminum or aluminum alloy surface which comprises immersing the surface for about 10 seconds in an aqueous solution of sodium carbonate and tri-sodium orthophosphate in the proportions of about 3 parts by weight of the carbonate to about 1 part by weightof the phosphate and having a pH value of 10 or more and a temperature of about 75 to 85 C.
- a process for improving the reflectivity of aluminum or aluminum alloy surfaces which comprises applying direct current anodic treatment in an electrolyte containing tri-sodium orthophosphate and sodium carbonate and having a pH value of 10 or more, immediately following a short simple immersion in the said electrolyte.
- a process for improving the reflectivity of aluminum or aluminum alloy surfaces which comprises immersing the surface in an electrolyte containing 15 per cent by weight of sodium carbonate and 5 per cent by weight of tri-sodium ortho-phosphate and having a temperature of from 75 to 85 C., after about 10 seconds immersion applying direct current anodic treatment for 10 to 15 minutes at a constant voltage which results in an initial current density of about 30 amperes per square foot of anode surface, and without interrupting the current withdrawing the anodic surface from the solution, then rinsing it in water and subjecting it to anodic treatment in a bath containing from 5 per cent to 40 per cent by weight of sodium bisulphate at a temperature ranging from 20 C. to 50 C. with current of a direct or alternating character for 10 to 15 minutes at a density of the order of 5 amperes per square foot of bright surface.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Electroplating Methods And Accessories (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Description
Patented Oct. 19, 1937 PATENT OFFICE SURFACE TREATMENT OF ALUMINUM AND ALUMINUM ALLOYS Alfred Norman Douglas Pullen, London, England assignor to The British Aluminum Company Limited, London, England No Drawing. Application December 4, 1935, Se-
rial No. 52,932. In Great Britain December 17,
9 Claims.
This invention relates to the surface treatment of aluminum and aluminum alloys and more particularly to treatment directed to the improvement of the specular reflectivity of such surfaces.
Sheet aluminum as produced by the normal rolling process has an average specular reflectivity for light of about 65 per cent.
The reflectivity may be increased by processes such as polishing up to a figure of 75 per cent. to 80 per cent.'but on exposure to air this enhanced reflecting power decreases rapidly until a figure equivalent to that for normal rolled sheet is reached.
The object of the present invention is the provision of a method and means by which the specular reflectivity of an aluminum or aluminum alloy surface may be increased very considerably in a cheap, eflicient and permanent manner.
The present invention consists in a process for increasing the specular reflectivity of the surface of an aluminum or aluminum alloy article which comprises immersing the previously degreased article in an aqueous solution of sodium carbonate and tri-sodium orthophosphate to remove the normal oxide film, then immediately thereafter in the same solution subjecting the article to anodic treatment by direct current at a moderately high current density for a short time to stop the attack of the solution upon the article and continuing the anodic treatment by direct current at a lower current density, and, after washing in water, subjecting the article to further electrolytic treatment in a strong aqueous solution of sodium bisulphate.
The invention may be carried into effect in one way by way of example as follows:-
A piece of commercially pure rolled aluminum sheet is first degreased by suitable means such as cleaning in petrol, then, if necessary, it is buffed or otherwise polished mechanically. It is then given a. chemico-electrical treatment in a bath having the following composition and under the following conditions.
Electrolyte 15 per cent. by weight of sodium carbonate, per cent. by weight of trisodium ortho-phosphate in water. The solution to be heated to 80 0.:5.
Procedure The metal article is immersed in the bath with the result that solution of the metal by the alkaline electrolyte commences almost immediately. As soon as uniform attack is observed, approximately after seconds immersion, direct current at 5-6 volts is switched on, the aluminum being the anode, the current density applied being of the order of 30 amperes per square foot. An iron or steel cathode is used and procedure in the bath follows electro-plating practice to some extent,
e. g., the cathode is made to conform roughly to the anodic surface.
It is of advantage to have a bath which is of considerably larger dimensions than the electrodes. At the end of a short period, about 30 seconds, the current density automatically falls to about half the first value whilst the voltage is maintained approximately at the figure mentioned. The treatment is continued under these conditions for about 10 minutes. The article is then removed from the bath with the current still on but preferably reduced to a small value by suitable means, and immediately washed in clean water. The surface of the metal, particularly that one facing the cathode, has now a very bright appearance and it will be found that if the original specular reflectivity value was, say, 65 per cent, it has now been raised to perhaps 80 per cent. Besides the general bright appearance, it will be noticed that the surface of the metal now carries a thin film, presumably of aluminum oxide which shows brilliant interference colours.
For the following part of the treatment, that is to say, the provision of a protective oxide film, the metal is again subjected to an anodic process in another electrolyte, the composition of which and the conditions of operation being as follows Electrolyte Aqueous solution containing 25 per cent. by weight of sodium bisulphate.
Voltage 6-12 volts direct current, the aluminum being the anode.
Temperature of electrolyte Time of treatment 10-15 minutes.
The current density is of the order of 5 amperes per square foot.
Whilst a dual process has been described in the foregoing example, it is possible to carry out the process in two separate steps, a brightening and a final protective step which latter may, if necessary, be carried out by suitable known anodic processes.
General The figures given in the foregoing example are capable of modification without departing from the scope ofthe invention.
For example, for the first part of the treatment the composition of the electrolyte may include all strong alkaline electrolytes having a pH value of over 10, containing an ortho-phosphoric acid radicle corresponding in quantity to that contained in approximately 3 to 9 per cent, by weight of trisodium ortho-phosphate, and with akalinities due to the hydroxides or carbonates of the alkali metals such as sodium, potassium, lithium, with or without the addition of alkali metal salts such as, for instance, borates or chromates.
The temperature range of the electrolyte may extend from about 40 to about 100 C.
The applied voltage may be varied between limits of about 2 to about 20 volts. For this part direct current is to be used, which term is intended to include unidirectional current of any kind..
For the second part of the treatment the electrolyte may comprise, in addition to the aqueous solution of sodium bisulphate, aqueous solutions of such substances as sulphuric acid, chromium sulphate, chromium oxalate, chromic acid, boric acid, phosphoric acid, acetic acid or salts of such acids. The percentage of sodium bisulphate may be from 5 to 40 per cent. by weight, the temperature may be from 20-50 C. and the voltage from about 5 to about 30 volts. For this part the current may be of a direct or alternating character.
The film, presumably of aluminum oxide, produced by the second part of the process hereinbefore described, viz. the protective coating for the brightened surface is relatively hard but is quite transparent and differs from similar oxide films formed in other, e. g., sulphuric acid or oxalic acid, electrolytes in that it does not reduce the reflectivity value of the film produced in the first part of the process, in fact, in many instances it has been found that the reflectivity value has been slightly raised.
The process according to the invention is applicable to all kinds of surfaces either normal, polished or mat and in all cases results in a considerable increase of the specular reflectivity of the original material.
Whilst the foregoing particular example deals only with commercially pure rolled aluminum sheet, the scope of the invention is not limited thereto and aluminum alloys are included in the materials which are susceptible to beneficial treatment by the process according to the invention.
I claim:
1. A process for improving the reflectivity of the surface of a clean aluminum or aluminum alloy surface which comprises immersing the surface for a short time in an aqueous solution of sodium carbonate and tri-sodium orthophosphate in the proportions of about 3 parts by weight of the carbonate to about 1 part by weight of the phosphate and having a pH value of 10 or more and a temperature of about to C., and then without removing the surface from the solution applying direct current anodic treatment thereto.
2. A process as claimed in claim 1, including the further steps of washing the surface and providing a protective coating therefor. v
3. A process for improving the reflectivity of the surface of a clean aluminum or aluminum alloy surface which comprises immersing the surface for a short time in an aqueous solution of sodium carbonate and tri-sodium orthophosphate in the proportions of about 3 parts by weight of the carbonate to about 1 part by weight of the phosphate and having a pH value of 10 or more and a temperature of about 75 to 85 C., then washing the surface and providing a protective coating therefor by anodic treatment in an aqueous solution of sodium bisulphate.
4. A process as claimed in claim 3 wherein the sodium bisulphate solution contains from 5% to 40% by weight of the salt, is used at temperatures ranging from 20 C. to 50 C., and the current which may be direct or alternating in character is applied for about 10 to 15 minutes at a density of the order of 5 amperes per square foot of bright surface.
5. A process for improving the reflectivity of the surface of a clean aluminum or aluminum alloy surface which comprises immersing the surface for about 10 seconds in an aqueous solution of sodium carbonate and tri-sodium orthophosphate in the proportions of about 3 parts by weight of the carbonate to about 1 part by weightof the phosphate and having a pH value of 10 or more and a temperature of about 75 to 85 C. and then without removing the surface from the solution applying direct current anodic treatment thereto for about 10 to 15 minutes at a constant voltage which results in an initial current density of about 30 amperes per square foot of anode surface, then washing the surface and providing a protective coating therefor by anodic treatment in an aqueous solution of sodium bisulphate containing from 5% to 40% by weight of the bisulphate, the current, which may be alternating or direct in character being applied for about 10 to 15 minutes at a density of the order of 5 amperes per square foot of bright surface.
6. A process for improving the reflectivity of aluminum or aluminum alloy surfaces which comprises applying direct current anodic treatment in an electrolyte containing tri-sodium orthophosphate and sodium carbonate and having a pH value of 10 or more, immediately following a short simple immersion in the said electrolyte.
7. A process as claimed in claim 6 followed by rinsing and applying further anodic treatment with current of a direct or alternating character in an acid electrolyte containing from 5% to 40% sodium bisulphate.
8. A process as claimed in claim 6 wherein the period of the immersion treatment is of the order of 10 seconds and the alkaline electrolyte has an ortho-phosphoric radicle content approximately equal to that contained in from 3 to 9 per cent by weight of sodium ortho-phosphate.
9. A process for improving the reflectivity of aluminum or aluminum alloy surfaces which comprises immersing the surface in an electrolyte containing 15 per cent by weight of sodium carbonate and 5 per cent by weight of tri-sodium ortho-phosphate and having a temperature of from 75 to 85 C., after about 10 seconds immersion applying direct current anodic treatment for 10 to 15 minutes at a constant voltage which results in an initial current density of about 30 amperes per square foot of anode surface, and without interrupting the current withdrawing the anodic surface from the solution, then rinsing it in water and subjecting it to anodic treatment in a bath containing from 5 per cent to 40 per cent by weight of sodium bisulphate at a temperature ranging from 20 C. to 50 C. with current of a direct or alternating character for 10 to 15 minutes at a density of the order of 5 amperes per square foot of bright surface.
ALFRED NORMAN DOUGLAS PULLEN.
' and specified as me British Aluminium Company Limited, of London, Eng- CERTIFICATE CORRECTION. Patent No. 2,096,509. s October 1 9 1957. ALFRED NORMAN DOUGLAS.IU'. L ILEH,
It is hereby certified that the name e1 the assignee in the above numbered patent was erroneously deseribed and specified as "The British Aluminum Company Limited whereas said name should have been described land, as shown by the record of assignments in this office; and that the said Letters Patent should be read with this orrectioh therein that the ssmemay; conform to the record of the case in the Patent Office. Signed and sealed this 25th day of January, A. n. 1938.
I fienry Van Arsdale, (Seal) Acting Cemmissioner of Patents.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB36187/34A GB449162A (en) | 1934-12-17 | 1934-12-17 | Improvements in and relating to the surface treatment of aluminium and aluminium alloys |
Publications (1)
Publication Number | Publication Date |
---|---|
US2096309A true US2096309A (en) | 1937-10-19 |
Family
ID=10385767
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US52932A Expired - Lifetime US2096309A (en) | 1934-12-17 | 1935-12-04 | Surface treatment of aluminum and aluminum alloys |
Country Status (4)
Country | Link |
---|---|
US (1) | US2096309A (en) |
DE (1) | DE661266C (en) |
FR (1) | FR798956A (en) |
GB (1) | GB449162A (en) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2506582A (en) * | 1945-06-20 | 1950-05-09 | Mateosian Edward Der | Electrolytic polishing of metals |
US2647865A (en) * | 1947-09-24 | 1953-08-04 | Freud Herbert Manfred | Brightening aluminum and aluminum alloy surfaces |
US2671717A (en) * | 1950-08-29 | 1954-03-09 | Gen Electric | Chemical brightening of aluminum |
US2968577A (en) * | 1955-07-08 | 1961-01-17 | Vaw Ver Aluminium Werke Ag | Method and apparatus for polishing metals |
US3041259A (en) * | 1959-07-31 | 1962-06-26 | Hanson Van Winkle Munning Co | Cleaning aluminum surfaces |
US3378669A (en) * | 1967-06-30 | 1968-04-16 | Olin Mathieson | Method of making non-porous weld beads |
US3622223A (en) * | 1970-01-16 | 1971-11-23 | Brakell Products Pty Ltd | Projection screens |
FR2404683A1 (en) * | 1977-09-30 | 1979-04-27 | Shokosha Kk | ELECTROLYTIC TREATMENT OF ARTICLES IN ALUMINUM OR ALUMINUM ALLOYS TO FORM A SHINY FILM |
US4247378A (en) * | 1979-09-07 | 1981-01-27 | The British Aluminum Company Limited | Electrobrightening of aluminium and aluminium-base alloys |
US4270957A (en) * | 1977-06-03 | 1981-06-02 | Ford Motor Company | Method for cleaning aluminum articles |
US4988401A (en) * | 1988-06-15 | 1991-01-29 | Cegedur Pechiney Rhenalu | Process for sticking rubber to aluminum |
US10876211B2 (en) | 2011-09-16 | 2020-12-29 | Prc-Desoto International, Inc. | Compositions for application to a metal substrate |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE763172C (en) * | 1937-05-26 | 1953-05-11 | Ver Alluminium Werke A G | Process for the production of smooth and shiny surfaces on objects made of aluminum and aluminum alloys |
FR1005928A (en) * | 1947-10-17 | 1952-04-17 | Fr Hispano Suiza Soc | Improvements made to electrolytic polishing processes and baths for their implementation |
US4169770A (en) | 1978-02-21 | 1979-10-02 | Alcan Research And Development Limited | Electroplating aluminum articles |
FR2465017A1 (en) * | 1979-09-07 | 1981-03-20 | British Aluminium Co Ltd | Electro-brightening aluminium and its alloys - in agitated aq. soln. of carbonate and phosphate |
US6763875B2 (en) | 2002-02-06 | 2004-07-20 | Andersen Corporation | Reduced visibility insect screen |
CN112683203B (en) * | 2021-01-08 | 2021-12-07 | 山东创新精密科技有限公司 | Method for detecting coarse crystal layer of aluminum alloy |
-
1934
- 1934-12-17 GB GB36187/34A patent/GB449162A/en not_active Expired
-
1935
- 1935-12-04 US US52932A patent/US2096309A/en not_active Expired - Lifetime
- 1935-12-09 FR FR798956D patent/FR798956A/en not_active Expired
- 1935-12-14 DE DEB172180D patent/DE661266C/en not_active Expired
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2506582A (en) * | 1945-06-20 | 1950-05-09 | Mateosian Edward Der | Electrolytic polishing of metals |
US2647865A (en) * | 1947-09-24 | 1953-08-04 | Freud Herbert Manfred | Brightening aluminum and aluminum alloy surfaces |
US2671717A (en) * | 1950-08-29 | 1954-03-09 | Gen Electric | Chemical brightening of aluminum |
US2968577A (en) * | 1955-07-08 | 1961-01-17 | Vaw Ver Aluminium Werke Ag | Method and apparatus for polishing metals |
US3041259A (en) * | 1959-07-31 | 1962-06-26 | Hanson Van Winkle Munning Co | Cleaning aluminum surfaces |
US3378669A (en) * | 1967-06-30 | 1968-04-16 | Olin Mathieson | Method of making non-porous weld beads |
US3622223A (en) * | 1970-01-16 | 1971-11-23 | Brakell Products Pty Ltd | Projection screens |
US4270957A (en) * | 1977-06-03 | 1981-06-02 | Ford Motor Company | Method for cleaning aluminum articles |
FR2404683A1 (en) * | 1977-09-30 | 1979-04-27 | Shokosha Kk | ELECTROLYTIC TREATMENT OF ARTICLES IN ALUMINUM OR ALUMINUM ALLOYS TO FORM A SHINY FILM |
US4247378A (en) * | 1979-09-07 | 1981-01-27 | The British Aluminum Company Limited | Electrobrightening of aluminium and aluminium-base alloys |
US4988401A (en) * | 1988-06-15 | 1991-01-29 | Cegedur Pechiney Rhenalu | Process for sticking rubber to aluminum |
US10876211B2 (en) | 2011-09-16 | 2020-12-29 | Prc-Desoto International, Inc. | Compositions for application to a metal substrate |
Also Published As
Publication number | Publication date |
---|---|
GB449162A (en) | 1936-06-17 |
FR798956A (en) | 1936-05-29 |
DE661266C (en) | 1938-06-15 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2096309A (en) | Surface treatment of aluminum and aluminum alloys | |
US2708655A (en) | Electrolytic polishing of aluminum | |
FR2587370A1 (en) | PROCESS FOR PRODUCING SLICED STEEL SLAB ETAMEE AND NICKELEE FOR SOLDERED PRESERVES | |
US2647865A (en) | Brightening aluminum and aluminum alloy surfaces | |
US2703781A (en) | Anodic treatment of aluminum surfaces | |
US2108603A (en) | Production of aluminum reflecting surfaces | |
US2108604A (en) | Aluminum reflector | |
US2541083A (en) | Electroplating on aluminum | |
US2339806A (en) | Surface treatment of aluminum and aluminum alloys | |
JP3506827B2 (en) | Surface-treated aluminum material and method for producing the same | |
US4356069A (en) | Stripping composition and method for preparing and using same | |
JPS58177494A (en) | Anodically oxidizing bath for aluminum-clad part and anodic oxidation | |
US4784732A (en) | Electrolytic formation of an aluminum oxide layer | |
US2728720A (en) | Method of producing an electroplate of nickel on magnesium and the magnesium-base alloys | |
US3349014A (en) | Method and composition for the treatment of an aluminum surface | |
US3804731A (en) | Process for forming hard anodic oxide film on aluminum base alloy | |
US2578898A (en) | Electrolytic removal of metallic coatings from various base metals | |
JPS58164800A (en) | Electrolytic peeling method | |
US2095519A (en) | Method for producing galvanic coatings on aluminum or aluminum alloys | |
US2607722A (en) | Electrolytic polishing of stainless steel | |
US2557823A (en) | Method of forming a composite article comprising steel and silver | |
US2739932A (en) | Electrodepositing chromium on aluminum | |
US3365377A (en) | Method of sealing anodized aluminum | |
US3785940A (en) | Method for electrolytically treating the surface of a steel plate with a chromate solution | |
US1953998A (en) | Anodic coating of zinc base metals |