US2339806A - Surface treatment of aluminum and aluminum alloys - Google Patents
Surface treatment of aluminum and aluminum alloys Download PDFInfo
- Publication number
- US2339806A US2339806A US265339A US26533939A US2339806A US 2339806 A US2339806 A US 2339806A US 265339 A US265339 A US 265339A US 26533939 A US26533939 A US 26533939A US 2339806 A US2339806 A US 2339806A
- Authority
- US
- United States
- Prior art keywords
- aluminum
- treatment
- surface treatment
- bath
- alloys
- 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
- 229910052782 aluminium Inorganic materials 0.000 title description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title description 11
- 229910000838 Al alloy Inorganic materials 0.000 title description 8
- 238000004381 surface treatment Methods 0.000 title description 3
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 12
- 238000000034 method Methods 0.000 description 8
- 239000003792 electrolyte Substances 0.000 description 7
- 238000002310 reflectometry Methods 0.000 description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 description 5
- 150000003863 ammonium salts Chemical class 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000001099 ammonium carbonate Substances 0.000 description 2
- 235000012501 ammonium carbonate Nutrition 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005282 brightening Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000004254 Ammonium phosphate Substances 0.000 description 1
- 239000004135 Bone phosphate Substances 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 1
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 1
- 239000011609 ammonium molybdate Substances 0.000 description 1
- 229940010552 ammonium molybdate Drugs 0.000 description 1
- 235000018660 ammonium molybdate Nutrition 0.000 description 1
- 229910000148 ammonium phosphate Inorganic materials 0.000 description 1
- 235000019289 ammonium phosphates Nutrition 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-M bisulphate group Chemical group S([O-])(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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
Definitions
- This invention relates to the surface treatment of aluminum and aluminum alloys and more especially to treatment directed to the improvement of the reflectivity of such surfaces.
- the object of the present invention is the provision of a method and means by which the reflectivity of an aluminum or aluminum alloy surface may be increased very considerably in a cheap, efficient and permanent manner.
- beneficial results are obtained by modifying the composition of the first i. e. the alkaline bath in the above described process.
- beneficial results include a re-' duction of the current density, including current surges (up to 30 to 40% in some cases) and a less pronounced preliminary etch, giving a sharper reflected image and less prominence to any structural and other markings which may exist on the surface of the metal.
- the present invention consists in 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 electrolyte formed as an aqueous solution containing sodium carbonate, with or without additions of sodium tribasic orthophosphate, and containing additions of ammonia, ammonium carbonate, ammonium phosphate, ammonium molybdate or other ammonium salts, and having av pH value of 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.
- an electrolyte formed as an aqueous solution containing sodium carbonate, with or without additions of sodium tribasic orthophosphate, and containing additions of ammonia, ammonium carbonate, ammonium phosphate, ammonium molybdate or other ammonium salts, and having av pH value of or more and a temperature of about 75 to 85 C. and then without removing the surface from
- Example I 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:
- the piece of sheet is immersed in the bath with the result that sol tion of the metal by the alkaline electrolyte commences almost immediately.
- direct current at 10-14 volts is switched on, the aluminum being the anode, the current density applied being of the order of 10 to 15 amperes per square foot.
- An iron or steel cathode is used and procedure in the bath follows electro-plating practice to some extent.
- Example II The electrolyte has the following composition:
- the solution is used at a temperature of about 80 C. and the treatment may be followed by treatment in a bisulphate bath for the provision of a protective film as described in detail in specification No. 2,096,309.
- the specified additive materials in either case, such as phosphates oi the alkali metals. being from about 0.5 to about 5.0% by weight. It will be noted that the concentration of the ammonium salt used in Examples 1 and 2 ranges from 1 to 2%, this being an advantageous range.
- the step which comprises electrolytic brightening of said surface by subjecting it to direct current anodic treatment in an aqueous electrolyte containing about 3-20 per cent sodium carbonate together with about 0.5-5 per cent of an ammonium salt, said electrolyte having a pH value of at least about 10.
Description
Patented Jan. 25, 1944 SURFACE TREATMENT OF ALUMINUM AND Q ALUMINUM ALLOYS Alfred Norman Douglas Pullen,
London, England,
assignor, by mesne assignments, to Aluminum Company of America, ration of Pennsylvania Pittsburgh, Pa., a corpo- No Drawing. Application March 31, 1939, Serial No. 265,339. In Great Britain Aprll 7, 1938 2 Claims. (Cl. 204-140) This invention relates to the surface treatment of aluminum and aluminum alloys and more especially to treatment directed to the improvement of the reflectivity of such surfaces.
The object of the present invention is the provision of a method and means by which the reflectivity of an aluminum or aluminum alloy surface may be increased very considerably in a cheap, efficient and permanent manner.
In my prior Patent Specification No. 2,096,309 I have described a process for increasing the refiectivity 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 sodium orthophosphate to remove the normal oxide film, then 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.
I have found, as a result of careful and extended research, that beneficial results are obtained by modifying the composition of the first i. e. the alkaline bath in the above described process. These beneficial results include a re-' duction of the current density, including current surges (up to 30 to 40% in some cases) and a less pronounced preliminary etch, giving a sharper reflected image and less prominence to any structural and other markings which may exist on the surface of the metal.
The present invention consists in 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 electrolyte formed as an aqueous solution containing sodium carbonate, with or without additions of sodium tribasic orthophosphate, and containing additions of ammonia, ammonium carbonate, ammonium phosphate, ammonium molybdate or other ammonium salts, and having av pH value of 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.
Several ways of carrying the invention into effect will now be described by way of example.
Example I 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:
15% anhydrous sodium carbonate. 6% crystalline tribasic sodium orthophosphate. 1% ammonium carbonate.
The piece of sheet is immersed in the bath with the result that sol tion of the metal by the alkaline electrolyte commences almost immediately. As soon as uniform attack is observed direct current at 10-14 volts is switched on, the aluminum being the anode, the current density applied being of the order of 10 to 15 amperes per square foot. An iron or steel cathode is used and procedure in the bath follows electro-plating practice to some extent.
It is of advantage to have a bath which is of considerably larger dimensions than the electrodes. At the end of a short period, not more than 20 seconds the current density automatically falls to about half the first valuewhilst 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, preferably with the current still on, and immediately washed in clean water. The surface of the metal has now a very bright appearance and it will be found that if the original reflectivity value was, say, it has now been raised to perhaps 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.
Example II The electrolyte has the following composition:
15% anhydrous sodium carbonate 2% ammonium orthophosphate and the procedure follows that of Example I.
In all the above examples the percentages are by weight, the solution is used at a temperature of about 80 C. and the treatment may be followed by treatment in a bisulphate bath for the provision of a protective film as described in detail in specification No. 2,096,309.
General Although temperatures of about 75 to are preferable for the alkaline bath, good results under certain conditions may be obtained over the temperature range of 55 to C.
2 a f aasaaoo n is important that the pH value 0! the alkaline solution should be 10 or more, due to the presence of carbonates or hydroxides or both, the
ercentages being from about 3 to about 20% by weight of sodium carbonate or irom about 0.1 to about 3.0% by weight of sodium or potassium hydroxide, the specified additive materials in either case, such as phosphates oi the alkali metals. being from about 0.5 to about 5.0% by weight. It will be noted that the concentration of the ammonium salt used in Examples 1 and 2 ranges from 1 to 2%, this being an advantageous range.
I claim:
1. In a process for improving the reflectivity or aluminum or aluminum alloy surfaces and producing a surface with decreased prominence of structural and other markings, the step which comprises electrolytic brightening of said surface by subjecting it to direct current anodic treatment in an aqueous electrolyte containing about 3-20 per cent sodium carbonate together with about 0.5-5 per cent of an ammonium salt, said electrolyte having a pH value of at least about 10.
2. In a process for improving the reflectivity 0! aluminum or aluminum alloy surfaces and producing a surface with decreased prominence oi l0. structural and other markings, the step which comprises electrolytic brightening oi said surface by subjecting it to direct current anodic treatment in an aqueous electrolyte containing about 3-20 per cent sodium carbonate and about 0.5-5
1| per cent sodium phosphate together with about 0.5-5 per cent of an ammonium salt, said electrolyte having a pH value of at least about 10.
ALFRED NORMAN DOUGLAS m.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB10634/38A GB513530A (en) | 1938-04-07 | 1938-04-07 | Improvements in and relating to the surface treatment of aluminium and aluminium alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2339806A true US2339806A (en) | 1944-01-25 |
Family
ID=9971481
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US265339A Expired - Lifetime US2339806A (en) | 1938-04-07 | 1939-03-31 | Surface treatment of aluminum and aluminum alloys |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US2339806A (en) |
| FR (1) | FR852754A (en) |
| GB (1) | GB513530A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2428141A (en) * | 1940-09-25 | 1947-09-30 | Gen Motors Corp | Process for cleaning, stripping, and polishing metal surfaces |
| US2810161A (en) * | 1951-10-03 | 1957-10-22 | Jr Clare L Milton | Process for producing seamless cosmetic gloves |
| US2853441A (en) * | 1949-09-29 | 1958-09-23 | Flint Oliver | Surface treatment of uranium |
| US4247378A (en) * | 1979-09-07 | 1981-01-27 | The British Aluminum Company Limited | Electrobrightening of aluminium and aluminium-base alloys |
| US11476057B2 (en) * | 2019-07-03 | 2022-10-18 | Pacesetter, Inc. | Increasing capacitance of a capacitor |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2521106A (en) * | 1946-01-19 | 1950-09-05 | C G Coun Ltd | Method and bath for electropolishing |
| DE1237869B (en) * | 1961-03-15 | 1967-03-30 | Kyowa Hakko Kogyo Kk | Bath and process for anodic glazing of aluminum |
| 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 |
-
1938
- 1938-04-07 GB GB10634/38A patent/GB513530A/en not_active Expired
-
1939
- 1939-03-31 US US265339A patent/US2339806A/en not_active Expired - Lifetime
- 1939-04-06 FR FR852754D patent/FR852754A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2428141A (en) * | 1940-09-25 | 1947-09-30 | Gen Motors Corp | Process for cleaning, stripping, and polishing metal surfaces |
| US2853441A (en) * | 1949-09-29 | 1958-09-23 | Flint Oliver | Surface treatment of uranium |
| US2810161A (en) * | 1951-10-03 | 1957-10-22 | Jr Clare L Milton | Process for producing seamless cosmetic gloves |
| US4247378A (en) * | 1979-09-07 | 1981-01-27 | The British Aluminum Company Limited | Electrobrightening of aluminium and aluminium-base alloys |
| US11476057B2 (en) * | 2019-07-03 | 2022-10-18 | Pacesetter, Inc. | Increasing capacitance of a capacitor |
Also Published As
| Publication number | Publication date |
|---|---|
| FR852754A (en) | 1940-03-02 |
| GB513530A (en) | 1939-10-16 |
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