GB1590597A - Treating a1 or a1 alloy surfaces - Google Patents
Treating a1 or a1 alloy surfaces Download PDFInfo
- Publication number
- GB1590597A GB1590597A GB42769/77A GB4276977A GB1590597A GB 1590597 A GB1590597 A GB 1590597A GB 42769/77 A GB42769/77 A GB 42769/77A GB 4276977 A GB4276977 A GB 4276977A GB 1590597 A GB1590597 A GB 1590597A
- Authority
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- United Kingdom
- Prior art keywords
- coating
- solution
- aluminium
- nitrite
- silicate
- 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
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- 239000000956 alloy Substances 0.000 title 1
- 229910045601 alloy Inorganic materials 0.000 title 1
- 238000000576 coating method Methods 0.000 claims description 41
- 239000011248 coating agent Substances 0.000 claims description 35
- 239000000243 solution Substances 0.000 claims description 24
- 229910000838 Al alloy Inorganic materials 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000004411 aluminium Substances 0.000 claims description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 claims description 10
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 9
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 9
- 239000011575 calcium Substances 0.000 claims description 9
- 239000003973 paint Substances 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 239000012224 working solution Substances 0.000 claims description 8
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 7
- 238000012505 colouration Methods 0.000 claims description 7
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 6
- 229910001424 calcium ion Inorganic materials 0.000 claims description 6
- 238000010790 dilution Methods 0.000 claims description 6
- 239000012895 dilution Substances 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 239000011701 zinc Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 claims description 5
- 238000005260 corrosion Methods 0.000 claims description 5
- 230000007797 corrosion Effects 0.000 claims description 5
- -1 nitrite ions Chemical class 0.000 claims description 5
- 235000010288 sodium nitrite Nutrition 0.000 claims description 5
- MIZLGWKEZAPEFJ-UHFFFAOYSA-N 1,1,2-trifluoroethene Chemical group FC=C(F)F MIZLGWKEZAPEFJ-UHFFFAOYSA-N 0.000 claims description 4
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 4
- 239000012141 concentrate Substances 0.000 claims description 4
- 238000007654 immersion Methods 0.000 claims description 4
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- RZLVQBNCHSJZPX-UHFFFAOYSA-L zinc sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Zn+2].[O-]S([O-])(=O)=O RZLVQBNCHSJZPX-UHFFFAOYSA-L 0.000 claims description 4
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 claims description 3
- 238000009835 boiling Methods 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 229910052681 coesite Inorganic materials 0.000 claims description 3
- 229910052906 cristobalite Inorganic materials 0.000 claims description 3
- 238000010422 painting Methods 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 229910052682 stishovite Inorganic materials 0.000 claims description 3
- 229910052905 tridymite Inorganic materials 0.000 claims description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- LLSDKQJKOVVTOJ-UHFFFAOYSA-L calcium chloride dihydrate Chemical compound O.O.[Cl-].[Cl-].[Ca+2] LLSDKQJKOVVTOJ-UHFFFAOYSA-L 0.000 claims description 2
- 238000007739 conversion coating Methods 0.000 claims description 2
- 230000003247 decreasing effect Effects 0.000 claims description 2
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- 239000007921 spray Substances 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 description 3
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 229940005654 nitrite ion Drugs 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- BBEAQIROQSPTKN-UHFFFAOYSA-N pyrene Chemical compound C1=CC=C2C=CC3=CC=CC4=CC=C1C2=C43 BBEAQIROQSPTKN-UHFFFAOYSA-N 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- POWFTOSLLWLEBN-UHFFFAOYSA-N tetrasodium;silicate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-][Si]([O-])([O-])[O-] POWFTOSLLWLEBN-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- 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 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- AZFNGPAYDKGCRB-XCPIVNJJSA-M [(1s,2s)-2-amino-1,2-diphenylethyl]-(4-methylphenyl)sulfonylazanide;chlororuthenium(1+);1-methyl-4-propan-2-ylbenzene Chemical compound [Ru+]Cl.CC(C)C1=CC=C(C)C=C1.C1=CC(C)=CC=C1S(=O)(=O)[N-][C@@H](C=1C=CC=CC=1)[C@@H](N)C1=CC=CC=C1 AZFNGPAYDKGCRB-XCPIVNJJSA-M 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- GVEPBJHOBDJJJI-UHFFFAOYSA-N fluoranthrene Natural products C1=CC(C2=CC=CC=C22)=C3C2=CC=CC3=C1 GVEPBJHOBDJJJI-UHFFFAOYSA-N 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052914 metal silicate Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- MEFBJEMVZONFCJ-UHFFFAOYSA-N molybdate Chemical compound [O-][Mo]([O-])(=O)=O MEFBJEMVZONFCJ-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 235000010289 potassium nitrite Nutrition 0.000 description 1
- 239000004304 potassium nitrite Substances 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000019795 sodium metasilicate Nutrition 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
- C23C22/66—Treatment of aluminium or alloys based thereon
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S70/00—Details of absorbing elements
- F24S70/20—Details of absorbing elements characterised by absorbing coatings; characterised by surface treatment for increasing absorption
- F24S70/25—Coatings made of metallic material
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Sustainable Energy (AREA)
- General Chemical & Material Sciences (AREA)
- Thermal Sciences (AREA)
- Sustainable Development (AREA)
- Combustion & Propulsion (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Description
(54) TREATING Al OR Al SURFACES
(71) We, PYRENE CHEMICAL SERVICES
LIMITED, a British company of Ridgeway,
Iver, Buckinghamshire, SLO 9JJ, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a method for forming black coloured coatings on aluminium or aluminium alloy surfaces to improve their corrosion resistance and their stability as a base for paints. The invention also relates to a composition for use in such a method.
Conventionally, black coloured coatings have been formed by electrolytically developed colouration using anodic oxidation, electrolytic colouration, or dyeing painting or blackening by electroplating. However, it is not easy to obtain uniformly coloured coatings by electrolytic reactions, and these methods are complex, expensive and difficult to control.
Another known method for forming a black coating involves a chemical conversion using an aqueous solution containing a sulphide, a cyanide and molybdate and chromate ions. The waste from that treatment is difficult to treat and leads to undesirable pollution. It is also difficult to form uniform black coatings having sufficiently good appearance on a continuous basis.
A composition according to the invention comprises an aqueous solution which has a pH of from 9 to 12 and which contains nitrite, silicate, zinc and calcium and/or magnesium ions. A process for forming a black coloured coating on an aluminium or aluminium alloy surface, according to the invention, comprises contacting such a surface with a composition of the invention.
The structure and composition of the black coloured coating obtained by the process of the invention, and the conversion mechanism which is involved have not been elucidated, but it has been confirmed by fluorescent X-ray analysis that the coating comprises predominantly silicic acid, calcium and zinc. Such metal silicates are known to act as inhibitors on aluminium. It has been found that the addition of nitrite ion effectively promotes the chemical conversion reaction involved in forming the coating, and gives a uniform coating.
The aqueous treatment solution of the invention may be prepared either by dissolving each component separately in water and mixing the solutions or by preparing a dry mixture of the essential components and dissolving the mixture in water.
Suitable sources of nitrite ion include sodium nitrite and potassium nitrite. The concentration of this ion in the treatment solution must be from 0.1 to 15 g/l, calculated as NO2. At a concentration less than 0.1 g/l, no promotion effect in the black coloured coating is observed. A concentration higher than 15 g/l is uneconomic.
Zinc ion may be supplied in the form of, for example, the sulphate, phosphate or halide. Its concentration must be from 1 to 100 mg/l. At a concentration less than 1 mg/l, no black coloured coating is formed.
At a concentration higher than 100 mg/l, the coating is not satisfactory.
Calcium and/or magnesium ions may be included in the form of their halides, sulphates or phosphates, at a concentration of from I to 100 mg/l. At a concentration below this range, insufficient coating is obtained. At a concentration higher than 100 mg/l, the formation of the coating may be suppressed.
Silicate ion may be included in the treatment solution as, for example, a form of sodium silicate. Suitable forms are sodium metasilicate, sodium orthosilicate, sodium monosilicate and sodium bisilicate. The silicate concentration must be from I to 30 mg/l, calculated as SiO2. At a concentration less than I mg/l, etching will occur but no coating will be formed. At a concentration higher than 30 mg/l, the silicate inhibition effect is too great and the formation of a coating is inhibited.
The pH of the solution may be adjusted to a value of from 9 to 12 by using an alkali metal or ammonium hydroxide or carbonate.
If the pH of the composition is less than 9, the colouration of the black coating may be uneven and, at a pH higher than 12, the aluminium surface may be etched to an undesirable extent. thereby decreasing the colouration rate.
In use, the temperature of the solution is preferably from 80"C to its boiling point. At lower temperatures the colouration rate is relatively slow. The contact time, during which the coating is formed, is suitably from 10 to 40 minutes (by immersion in the treatment solution).
Prior to the coating step, the aluminium or aluminium alloy workpiece will usually be cleaned in a conventional manner. When the coating has been formed, the workpiece is usually rinsed with water and then dried in hot air.
Aluminium or aluminium alloys which can be treated in accordance with the process of the invention include rolled materials such as Al loop, 5052 S, 5082 S and 6063 S, as well as die-cast articles.
After the black coloured coating has been formed, conventional post-treatment steps can be carried out, if desired, to improve the corrosion resistance, workability for painting and fastness of the treated workpieces. These steps include the immersion into, or spraying with, a commercially available aqueous solution of a chromate or silicate, followed by drying. The corrosion resistance of the coating can be further improved by applying a clear paint, thereby ensuring also that the black coating is not easily stripped off on impact.
The following Examples illustrate the invention.
Example I
Specimens of Al 100 PH 24 aluminium alloy and 6063 S aluminium alloy were degreased with trifluoroethylene and then with an alkali.
A treatment solution was made up to contain 0.1 g/l of Na2O.SiO2.9H2O, 0.02 g/l of ZnSO4.7H2O, 0 08 g/l of CaCl2.2H2O and 2 g/l of sodium nitrite in water, and the pH of the solution was adjusted to 10-5 with sodium hydroxide. The temperature of a bath containing the solution was controlled within the range 80 to 100"C. and the degreased specimens were immersed in the solution for 30 minutes. Uniform deep black coloured coatings were obtained on both Al
100 P and 6063 S.
Immediately after the subsequent rinsing and drying, the resulting sample was immersed in a treating bath containing 8 4 g/l of Parcolene (registered Trade Mark) at 60"C. for 15 seconds and then dried. The resulting sample was then coated with a commercially available clear acrylic paint and baked at 130"C. for 20 minutes. The thickness of the coating ranged from 20 to 25 microns and the appearance of the sample was brown in colour.
Example 2
A sample of Al 100 PH 24 aluminium alloy was degreased with trifluoroethylene and then with an alkali.
An aqueous solution was made up to contain 002 g/l of Na2O.SiO2.9H2O, 002 g/l of ZnSO4.7H2O, 0 15 g/l of CaCI2.2H2O and 10 g/l of sodium nitrite, and the pH was adjusted to a value of I 110 with sodium hydroxide. The degreased aluminium sample was immersed in the resulting solution at a temperature of from 80 to 100"C. for 20 minutes to obtain a uniform coating.
Immediately after the subsequent rinsing and drying, the resulting sample was immersed in a treating bath and then coated with an acrylic paint and baked, all as described in Example 1.
The test pieces obtained in Examples I and 2 were then subjected to the salt spray test according to JIS Z-237 1. In both cases, the time in which white stains were developed was 48 hours when only the conversion coating had been applied but 120 hours after the chromate sealing step. For the product of Example 2, the time in which white stains developed was 500 hours after the acrylic paint had been applied. These results show that the durability of the chromate-sealed coating is about 2 5 times as high as that of the unsealed coating, and that the painted surface is more than 10 times as durable as the conversion coated surface.
It will be appreciated that the working solution of this invention may be prepared from a more concentrated composition. Accordingly, this invention provides dry compositions and aqueous concentrates which are suitable for dilution and, if necessary, basification to form such a working solution.
WHAT WE CLAIM IS: 1. An aqueous solution which has a pH of from 9 to 12 and which contains, per litre thereof, from 0.1 to 15 g nitrite ions calculated as NO2, from 1 to 30 mg silicate ions calculated as SiO2, from 1 to 100 mg zinc ions, and from 1 to 100 mg calcium and/or magnesium ions.
2. A solution according to claim 1 substantially as described in either of the Examples.
3. A dry composition which is suitable for dilution and, if necessary, basification to form a working solution according to claim 1 or claim 2 and which comprises nitrite, silicate, zinc and calcium and/or magnesium.
4. An aqueous concentrate suitable for dilution and, if necessary, basification to form a working solution according to claim 1 or claim 2 and which contains nitrite, silicate, zinc and calcium and/or magnesium ions.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (7)
- **WARNING** start of CLMS field may overlap end of DESC **.uneven and, at a pH higher than 12, the aluminium surface may be etched to an undesirable extent. thereby decreasing the colouration rate.In use, the temperature of the solution is preferably from 80"C to its boiling point. At lower temperatures the colouration rate is relatively slow. The contact time, during which the coating is formed, is suitably from 10 to 40 minutes (by immersion in the treatment solution).Prior to the coating step, the aluminium or aluminium alloy workpiece will usually be cleaned in a conventional manner. When the coating has been formed, the workpiece is usually rinsed with water and then dried in hot air.Aluminium or aluminium alloys which can be treated in accordance with the process of the invention include rolled materials such as Al loop, 5052 S, 5082 S and 6063 S, as well as die-cast articles.After the black coloured coating has been formed, conventional post-treatment steps can be carried out, if desired, to improve the corrosion resistance, workability for painting and fastness of the treated workpieces. These steps include the immersion into, or spraying with, a commercially available aqueous solution of a chromate or silicate, followed by drying. The corrosion resistance of the coating can be further improved by applying a clear paint, thereby ensuring also that the black coating is not easily stripped off on impact.The following Examples illustrate the invention.Example I Specimens of Al 100 PH 24 aluminium alloy and 6063 S aluminium alloy were degreased with trifluoroethylene and then with an alkali.A treatment solution was made up to contain 0.1 g/l of Na2O.SiO2.9H2O, 0.02 g/l of ZnSO4.7H2O, 0 08 g/l of CaCl2.2H2O and 2 g/l of sodium nitrite in water, and the pH of the solution was adjusted to 10-5 with sodium hydroxide. The temperature of a bath containing the solution was controlled within the range 80 to 100"C. and the degreased specimens were immersed in the solution for 30 minutes. Uniform deep black coloured coatings were obtained on both Al100 P and 6063 S.Immediately after the subsequent rinsing and drying, the resulting sample was immersed in a treating bath containing 8 4 g/l of Parcolene (registered Trade Mark) at 60"C. for 15 seconds and then dried. The resulting sample was then coated with a commercially available clear acrylic paint and baked at 130"C. for 20 minutes. The thickness of the coating ranged from 20 to 25 microns and the appearance of the sample was brown in colour.Example 2 A sample of Al 100 PH 24 aluminium alloy was degreased with trifluoroethylene and then with an alkali.An aqueous solution was made up to contain 002 g/l of Na2O.SiO2.9H2O, 002 g/l of ZnSO4.7H2O, 0 15 g/l of CaCI2.2H2O and 10 g/l of sodium nitrite, and the pH was adjusted to a value of I 110 with sodium hydroxide. The degreased aluminium sample was immersed in the resulting solution at a temperature of from 80 to 100"C. for 20 minutes to obtain a uniform coating.Immediately after the subsequent rinsing and drying, the resulting sample was immersed in a treating bath and then coated with an acrylic paint and baked, all as described in Example 1.The test pieces obtained in Examples I and 2 were then subjected to the salt spray test according to JIS Z-237 1. In both cases, the time in which white stains were developed was 48 hours when only the conversion coating had been applied but 120 hours after the chromate sealing step. For the product of Example 2, the time in which white stains developed was 500 hours after the acrylic paint had been applied. These results show that the durability of the chromate-sealed coating is about 2 5 times as high as that of the unsealed coating, and that the painted surface is more than 10 times as durable as the conversion coated surface.It will be appreciated that the working solution of this invention may be prepared from a more concentrated composition. Accordingly, this invention provides dry compositions and aqueous concentrates which are suitable for dilution and, if necessary, basification to form such a working solution.WHAT WE CLAIM IS: 1. An aqueous solution which has a pH of from 9 to 12 and which contains, per litre thereof, from 0.1 to 15 g nitrite ions calculated as NO2, from 1 to 30 mg silicate ions calculated as SiO2, from 1 to 100 mg zinc ions, and from 1 to 100 mg calcium and/or magnesium ions.
- 2. A solution according to claim 1 substantially as described in either of the Examples.
- 3. A dry composition which is suitable for dilution and, if necessary, basification to form a working solution according to claim 1 or claim 2 and which comprises nitrite, silicate, zinc and calcium and/or magnesium.
- 4. An aqueous concentrate suitable for dilution and, if necessary, basification to form a working solution according to claim 1 or claim 2 and which contains nitrite, silicate, zinc and calcium and/or magnesium ions.
- 5. A process of forming a coating on analuminium or aluminium alloy surface comprising contacting the surface with a solution according to claim 1 or claim 2.
- 6. A process according to claim 5 in which the solution is at a temperature of from 80"C to the boiling point of the solution.
- 7. A process according to claim 5 substantially as described in either of the Examples.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13232176A JPS5357142A (en) | 1976-11-05 | 1976-11-05 | Process for forming black coating on aluminum or aluminum alloy |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1590597A true GB1590597A (en) | 1981-06-03 |
Family
ID=15078571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB42769/77A Expired GB1590597A (en) | 1976-11-05 | 1977-10-14 | Treating a1 or a1 alloy surfaces |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5357142A (en) |
| CH (1) | CH615462A5 (en) |
| DE (1) | DE2739576A1 (en) |
| FR (1) | FR2370107A1 (en) |
| GB (1) | GB1590597A (en) |
| IT (1) | IT1089033B (en) |
| SE (1) | SE425008B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2223239A (en) * | 1988-08-24 | 1990-04-04 | Ardrox Pyrene Ltd | Phosphating process |
| CN114990538A (en) * | 2022-08-04 | 2022-09-02 | 山东一立动力科技股份有限公司 | Aluminum alloy surface blackening treatment method |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NO146439C (en) * | 1979-11-09 | 1982-09-29 | Inst Energiteknik | PROCEDURE FOR THE PREPARATION OF A DARK COLOR, WAVE LENGTH SELECTIVE ALUMINUM OIL |
| IT1152657B (en) * | 1982-09-28 | 1987-01-07 | Italia Alluminio | PROCEDURE FOR THE FORMATION OF A BLACK SELECTIVE LAYER ON SURFACES OF ALUMINUM BODIES AND ITS ALLOYS AND PRODUCTS SO OBTAINED |
| US4586977A (en) * | 1984-04-03 | 1986-05-06 | Imperial Clevite Inc. | Method of bonding a high temperature resistant polymeric material to an aluminum base substrate |
| US4555294A (en) * | 1984-04-03 | 1985-11-26 | Imperial Clevite Inc. | Inorganic composition adapted for use in bonding a high temperature resistant polymeric material to an aluminum base substrate |
| JP2756169B2 (en) * | 1990-02-26 | 1998-05-25 | 古河電気工業株式会社 | Manufacturing method of colored aluminum transmission line and its accessories |
| US5441773A (en) * | 1992-01-21 | 1995-08-15 | Betz Laboratories, Inc. | Composition and method of forming a black no-rinse conversion coating on metal surfaces |
| JP5634000B2 (en) * | 2006-04-06 | 2014-12-03 | 新日鐵住金株式会社 | Surface treated metal parts |
| FR3041695B1 (en) | 2015-09-25 | 2019-03-29 | Illinois Tool Works Inc. | DEGASSING TANK AND MOTOR VEHICLE COMPRISING SUCH A TANK |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1846844A (en) * | 1929-07-16 | 1932-02-23 | Gen Electric | Process of treating aluminum |
| FR1007070A (en) * | 1948-02-19 | 1952-04-30 | Vernal S A | Process for improving the appearance of the surface of objects made of aluminum or aluminum alloys |
| DE1914759A1 (en) * | 1969-03-22 | 1970-10-01 | Dettner Dr Heinz W | Hot alkaline baths |
| US3971674A (en) * | 1975-03-03 | 1976-07-27 | Aluminum Company Of America | Selective black coating for aluminum |
| US4145462A (en) * | 1976-06-09 | 1979-03-20 | Toyo Aluminium Kabushiki Kaisha | Process for producing solar collectors |
-
1976
- 1976-11-05 JP JP13232176A patent/JPS5357142A/en active Granted
-
1977
- 1977-09-02 DE DE19772739576 patent/DE2739576A1/en not_active Withdrawn
- 1977-10-14 GB GB42769/77A patent/GB1590597A/en not_active Expired
- 1977-11-02 FR FR7732926A patent/FR2370107A1/en active Granted
- 1977-11-03 IT IT29295/77A patent/IT1089033B/en active
- 1977-11-04 SE SE7712511A patent/SE425008B/en unknown
- 1977-11-04 CH CH1345577A patent/CH615462A5/en not_active IP Right Cessation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2223239A (en) * | 1988-08-24 | 1990-04-04 | Ardrox Pyrene Ltd | Phosphating process |
| GB2223239B (en) * | 1988-08-24 | 1992-09-23 | Ardrox Pyrene Ltd | Phosphating process |
| CN114990538A (en) * | 2022-08-04 | 2022-09-02 | 山东一立动力科技股份有限公司 | Aluminum alloy surface blackening treatment method |
| CN114990538B (en) * | 2022-08-04 | 2022-11-25 | 山东一立动力科技股份有限公司 | Aluminum alloy surface blackening treatment method |
Also Published As
| Publication number | Publication date |
|---|---|
| CH615462A5 (en) | 1980-01-31 |
| FR2370107B1 (en) | 1980-06-20 |
| SE425008B (en) | 1982-08-23 |
| JPS5551030B2 (en) | 1980-12-22 |
| IT1089033B (en) | 1985-06-10 |
| JPS5357142A (en) | 1978-05-24 |
| FR2370107A1 (en) | 1978-06-02 |
| DE2739576A1 (en) | 1978-05-18 |
| SE7712511L (en) | 1978-05-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PCNP | Patent ceased through non-payment of renewal fee |