CN103305822A - Treatment method for improving corrosion resistance of aluminum alloy - Google Patents
Treatment method for improving corrosion resistance of aluminum alloy Download PDFInfo
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- CN103305822A CN103305822A CN2013102122598A CN201310212259A CN103305822A CN 103305822 A CN103305822 A CN 103305822A CN 2013102122598 A CN2013102122598 A CN 2013102122598A CN 201310212259 A CN201310212259 A CN 201310212259A CN 103305822 A CN103305822 A CN 103305822A
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Abstract
The invention relates to a treatment method for improving corrosion resistance of aluminum alloy, and especially relates to a cobalt-based chrome-free chemical conversion treatment method. The treatment method is carried out according to the following steps of: firstly, respectively performing the pretreatment of oil removal, etching and activation on the aluminum alloy, then, performing chemical treatment on the aluminum alloy with cobalt salt chemical conversion solution, wherein the treatment parameters are shown as follows: the solution pH value is 4-10, the solution temperature is controlled to be 50-70 DEG C, the content of cobalt salt is 20-40g/L, the content of oxidant KMnO4 is 1-5g/L, the content of ligand oxalic acid is 20-40g/L, and the reaction time is 20-60 minutes. The treatment method has the following advantages that (1) the method is simple in technology, low in cost, environment-friendly and pollution-free; (2) the working temperature is low, and the process dimensions cannot be changed; (3) the film structure is compact, and is well adhered with the substrate; (4) the obtained chemical conversion film is strong in corrosion resistance, and the corrosion resistance of aluminum alloy surface is improved, further.
Description
Technical field
The present invention relates to the corrosion proof treatment process of a kind of raising aluminium alloy.Be particularly related to the corrosion proof cobalt-based Chrome-free of a kind of raising aluminium alloy chemical conversion processing method.
Background technology
Aluminium is the important foundation starting material of the national economic development because it has special chemistry, physical property becomes one of current the most frequently used Industrial Metal.To have active chemical property very easily oxidized but aluminium is because of it.
The surface treatment of aluminium not only can improve and improve chemical property, erosion resistance, wearability etc., thereby increase the service life, enlarge the range of application of aluminium, also can obtain beautiful colorful polychrome outward appearance, widen and promote decorate properties, and can give new physicals, obtain various novel functional materials and device.
What commonly use in the aluminum alloy chemically conversion method is chemical oxidation, is at a certain temperature, by chemical reaction, the oxygen in aluminum ion and the oxidizing solution is interacted, and forms the oxide film of one deck densification.The general oxide film that forms must possess two conditions: the one, in solution, contain the oxygenant that makes aluminium Surface Creation oxide film; The 2nd, in solution, contain activator.Make the aluminium surface in the oxidation filming process, constantly dissolved, in oxide film, form hole, the assurance oxide film is constantly grown up, is thickened.Large 100 ~ 200 times than natural oxidation film thickness of chemical oxide films, compare with anode oxide film, have the aluminium Influence of Fatigue Properties little, simple to operate, do not need the advantages such as electric energy, equipment is simple, cost is low, formation speed is fast, tack is good, can make separately protective layer or as the application bottom.
Chromic salt chemistry conversion film is considered to be in surface coating usually when suffering breakage still can be the offer the best rete of corrosion protection effect of metal.But hexavalent chromium is extremely malicious chemical substance, have strong toxicity and carcinogenesis, waste liquid serious environment pollution after the processing, China also announced chromic salt is carried out the use of limiting the quantity of in 2003, and cancelled synchronously use chromate conversion membrane technique with European Union before in July, 2006.
The chemical conversion of cobalt-based Chrome-free is exactly to replace the New Environment Protection Technology that hexavalent chromium is set up.So in order to widen the practical application of Chrome-free conversion film, must strengthen other conversion film and act on the fundamental research that aluminum alloy surface is processed.Thereby realize the breakthrough of technique, for health and the development active development of human future goes out novel membrane process.
The aluminum alloy trivalent chromium hydridization conversion film that has added inorganic inhibitor divalent cobalt and organic inhibitor ethanolamines in the disclosed a kind of film forming liquid of Chinese patent literature CN00813590.8, and this subject study is aluminium and aluminum alloy surface cobalt salt Conversion Coating Technology, by adjusting film forming accelerating (potassium permanganate) and part (sodium formiate), effectively regulate the hierarchy of control of cobalt salt content, pH value and temperature in the chemical conversion solution, have no report in the Chinese literature of publishing at home.
The cobalt salt conversion film that contains cobaltous acetate, sodium acetate, Calcium Fluoride (Fluorspan), rare earth addition and wetting agent than red, that Zhu Zufang writes " aluminium and aluminium alloy non-chromium process for treating surface progress " the middle research of recording, 60～65 ℃ of its treatment temps, the time is 20～30 min.And contain cobalt salt, film forming accelerating, part, additive of high density etc. in this subject study cobalt salt chemical conversion solution, by adjusting film forming accelerating (potassium permanganate) and part (sodium formiate), effectively regulate the hierarchy of control of cobalt salt content, pH value and temperature in the chemical conversion solution, have no report in the Chinese literature of publishing at home.
Summary of the invention
The present invention is directed to present cobalt-based chemical oxide film oxidation field treatment process cost high, the unsound shortcoming in treatment process top layer provides a kind of raising aluminium alloy corrosion proof treatment process, and the method is selected KMnO
4Be oxygenant, oxalic acid is part, has improved the compactness of rete, and because using a small amount of oxygenant to reduce process costs.It is achieved in that
The content of cobalt salt is the preferred Cobaltous nitrate hexahydrate of the wherein said cobalt salt of 20～40 g/L(), oxygenant KMnO
4Content be 1～5 g/L, the content of part oxalic acid is 20～40 g/L, all the other are water.PH is 4～10.
Compound method is as follows:
Cobaltous nitrate hexahydrate is dissolved in a certain amount of water, adds respectively a certain amount of KMnO
4With the abundant stirring and dissolving of oxalic acid, adopt the sodium hydroxide of 1 mol/L as pH adjusting agent.
The topmost prescription that is characterised in that cobalt salt chemical conversion solution of the present invention, this prescription obtains through screening, and screening process is as follows:
At first under the condition of same reaction temperature, film formation time, promotor, by to the corrosion proof comparison of the obtained conversion film of series of identical concentration different ligands, select one or two preferably part.
Secondly, for one or both parts that filter out among the conversion film preparation technology early stage, under the condition of same reaction temperature, film formation time, promotor, by changing the comparison of the obtained conversion film erosion resistance of ligand concentration, select an only concentration range.By further screening, the prescription of the most preferred cobalt salt chemical conversion solution that the present invention screens is as follows: pH is 7, and the content of Cobaltous nitrate hexahydrate is 26 g/L, KMnO
4Content be 1.5 g/L, the content of oxalic acid is 26 g/L, all the other are water.Wherein regulating the pH value is 7, adopts the sodium hydroxide of 1 mol/L as pH adjusting agent.
Compound method is as follows: fully be dissolved in a certain amount of water with electronic balance weighing 26 g Cobaltous nitrate hexahydrates, then add respectively 1.5 g KMnO
4With 26 g oxalic acid stirring and dissolving, in volumetric flask, demarcate at last 1L.
The prescription and the prior art that obtain after the screening compare test, test as follows:
The disclosed method of prior art: Chinese patent literature CN93101737.8,
The technology of the present invention: the method for the embodiment of the invention 3,
Process same batch 10 kilograms of aluminum alloy materials with above-mentioned two kinds of methods, result such as following table:
| ? | Treatment effect | The treatment solution consumption | Treatment time | The drop time | Salt mist experiment |
| Prior art | Faint yellow | 50L | 30min | 7.78s | Can reach the solidity to corrosion standard of 168h |
| The technology of the present invention | Rete is transparent in obvious color | 30L | 30min | 15.43s | 168h is without obvious hot spot |
(1) drop solution composition ratio is: hydrochloric acid 25 mL of 4 mol/L, potassium bichromate 0.6 g, after solution prepared, aluminium flake pros and cons drop 2 ~ 3 times, with stopwatch record conversion film surface point dropping liquid color by the green time of xanthochromia, be the corrosion-resistant time, and average.
Through above contrast experiment, prove that method treatment effect of the present invention is good, more superior than prior art.
By above experiment, prove that cobalt salt chemical conversion solution of the present invention has following beneficial effect.
It is few that oxygenant of the present invention has usage quantity, can regulate film layer structure by consumption, and working conditions is stable, but the advantages such as flexible operating.And use oxygenant KMnO
4More regular than the formed film densification of general oxygenant.Secondly, the film layer structure that uses part oxalic acid to obtain is stable.And reaction solution and rete environmentally safe thereof demonstrate great superiority in environmental protection industry.Aluminum alloy surface chemical oxidation method technique is simple, easy handling, and process treatment process has been simplified in the control of the equipment and process that need not mix greatly.Surface chemistry oxidation of the present invention has following advantage:
Description of drawings
Accompanying drawing is the scanning electron microscope diagram of embodiment 1.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in further detail.
Embodiment 1:
Aluminum alloy surface cobalt-based chemical conversion membrane preparation method, this implementation method is carried out as follows:
(1) pre-treatment
Fine aluminium is soaked 3 min in dehydrated alcohol, washing; Then etch 30 s take out after washing to remove surperficial natural oxide layer in 70 ℃ 1.5 mol/L NaOH; Put at last 1.5 mol/L HNO
3In carry out 15 s acid-base neutralisations, the washing, dry up.
(2) the cobalt salt chemical oxidation liquid is processed
PH is 7, and solution temperature is controlled at 50 ℃, and the content of cobalt salt is 26 g/L, oxygenant KMnO
4Content be 1.5 g/L, the content of part oxalic acid is 26 g/L.Reaction is carried out removing the aluminium flake washing behind 35 min, and ultrasonic cleaning 5 min dry up.
Embodiment 2:
Aluminum alloy surface cobalt-based chemical conversion membrane preparation method, this implementation method is carried out as follows:
Pre-treatment
Fine aluminium is soaked 3 min in dehydrated alcohol, washing; Then etch 30 s take out after washing to remove surperficial natural oxide layer in 60 ℃ 1.5 mol/L NaOH; Put at last 1.5 mol/L HNO
3In carry out 15 s acid-base neutralisations, the washing, dry up.
The cobalt salt chemical oxidation liquid is processed
PH is 7, and solution temperature is controlled at 60 ℃, and the content of cobalt salt is 24 g/L, oxygenant KMnO
4Content be 1.2 g/L, the content of part oxalic acid is 24 g/L.Reaction is carried out removing the aluminium flake washing behind 30 min, and ultrasonic cleaning 5 min dry up.
Embodiment 3:
Aluminum alloy surface cobalt-based chemical conversion membrane preparation method, this implementation method is carried out as follows:
Pre-treatment
Fine aluminium is soaked 3 min in dehydrated alcohol, washing; Then etch 30 s take out after washing to remove surperficial natural oxide layer in 60 ℃ 1.5 mol/L NaOH; Put at last 1.5 mol/L HNO
3In carry out 15 s acid-base neutralisations, the washing, dry up.
The cobalt salt chemical oxidation liquid is processed
PH is 7, and solution temperature is controlled at 70 ℃, and the content of cobalt salt is 26 g/L, oxygenant KMnO
4Content be 1.5 g/L, the content of part oxalic acid is 26 g/L.Reaction is carried out removing the aluminium flake washing behind 25 min, and ultrasonic cleaning 5 min dry up.
Claims (3)
1. one kind is improved the corrosion proof treatment process of aluminium alloy, it is characterized in that it carries out according to following step: at first aluminium alloy is carried out respectively the pre-treatment of oil removing, etch, activation, then adopt cobalt salt chemical conversion solution that it is carried out chemical treatment: solution temperature is controlled at 50～70 ℃, reaction times is 20～60 min, wherein cobalt salt chemical conversion solution formula is as follows: the content of cobalt salt is 20～40 g/L, oxygenant KMnO
4Content be 1～5 g/L, the content of part oxalic acid is 20～40 g/L, pH is 4～10.
2. the corrosion proof treatment process of a kind of raising aluminium alloy according to claim 1 is characterized in that described cobalt salt chemical conversion solution formula is as follows: cobalt salt: 20～30 g/L, KMnO
4: 1～4 g/L, oxalic acid: 20～30 g/L, pH are 6～8.
3. the corrosion proof treatment process of a kind of raising aluminium alloy according to claim 1, it is characterized in that described cobalt salt chemical conversion solution formula is as follows: pH is 7, and the content of Cobaltous nitrate hexahydrate is 26 g/L, KMnO
4Content be 1.5 g/L, the content of oxalic acid is 26 g/L, all the other are water, adopt the sodium hydroxide of 1 mol/L as pH adjusting agent, compound method is as follows: Cobaltous nitrate hexahydrate is dissolved in the water, adds respectively KMnO
4With the abundant stirring and dissolving of oxalic acid, adopting the sodium hydroxide of 1 mol/L is 7 as pH adjusting agent adjusting pH value.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106350856A (en) * | 2016-09-11 | 2017-01-25 | 经阁铝业科技股份有限公司 | Process for treating anodic electrophoretic surfaces of aluminum section bars |
| US10174250B2 (en) | 2014-04-01 | 2019-01-08 | Atotech Deutschland Gmbh | Composition and process for metallizing nonconductive plastic surfaces |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03240971A (en) * | 1990-02-16 | 1991-10-28 | Nisshin Steel Co Ltd | Blackening treatment of al, al alloy or steel sheet plated with same |
| CN101054664A (en) * | 2007-03-06 | 2007-10-17 | 陈东初 | Chromium-free treating liquid for preparing erosion-resisting oxide film on aluminum alloy surface, treating and using method thereof |
| CN102575357A (en) * | 2009-07-02 | 2012-07-11 | 日本帕卡濑精株式会社 | Chromium- and fluorine-free chemical conversion treatment solution for metal surfaces, metal surface treatment method, and metal surface coating method |
-
2013
- 2013-05-31 CN CN2013102122598A patent/CN103305822A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03240971A (en) * | 1990-02-16 | 1991-10-28 | Nisshin Steel Co Ltd | Blackening treatment of al, al alloy or steel sheet plated with same |
| CN101054664A (en) * | 2007-03-06 | 2007-10-17 | 陈东初 | Chromium-free treating liquid for preparing erosion-resisting oxide film on aluminum alloy surface, treating and using method thereof |
| CN102575357A (en) * | 2009-07-02 | 2012-07-11 | 日本帕卡濑精株式会社 | Chromium- and fluorine-free chemical conversion treatment solution for metal surfaces, metal surface treatment method, and metal surface coating method |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10174250B2 (en) | 2014-04-01 | 2019-01-08 | Atotech Deutschland Gmbh | Composition and process for metallizing nonconductive plastic surfaces |
| US10377947B2 (en) | 2014-04-01 | 2019-08-13 | Atotech Deutschland Gmbh | Composition and process for metallizing nonconductive plastic surfaces |
| CN106350856A (en) * | 2016-09-11 | 2017-01-25 | 经阁铝业科技股份有限公司 | Process for treating anodic electrophoretic surfaces of aluminum section bars |
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Application publication date: 20130918 |