CN102560516B - Magnesium alloy surface homogenization pretreatment process - Google Patents
Magnesium alloy surface homogenization pretreatment process Download PDFInfo
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- CN102560516B CN102560516B CN201210031832.0A CN201210031832A CN102560516B CN 102560516 B CN102560516 B CN 102560516B CN 201210031832 A CN201210031832 A CN 201210031832A CN 102560516 B CN102560516 B CN 102560516B
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- magnesium alloy
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- 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
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
- C23G1/22—Light metals
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- 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
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
-
- 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
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/12—Light metals
Abstract
The invention discloses a magnesium alloy surface homogenization pretreatment process, comprising the steps of: a, polishing: polishing grease, oxide coatings, corrosion products and corners on the surface of a magnesium alloy so that the surface of the magnesium alloy is clean and fresh; b, alkaline degreasing treatment: preparing an alkaline degreasing solution, putting the polished magnesium alloy into the alkaline degreasing solution, and moderately stirring at a temperature of 65-80 DEG C for 5-10min; c, acidic activation treatment: preparing an acidic activation solution, putting the magnesium alloy after the alkaline degreasing treatment into the acidic activation solution, and moderately stirring at room temperature for 30-60s; and d, alkaline adjustment: preparing an alkaline adjustment solution, putting the magnesium alloy after the acidic activation treatment into the alkaline adjustment solution, and moderately stirring at a temperature of 65-80 DEG C for 5-30min, wherein the magnesium alloy is cleaned through running water for 3min between each two steps. Through the process disclosed by the invention, the problem of unevenness of surface chemical compositions and electrochemistry of the magnesium alloy is solved, the obtained surface films are more even and compact, and the protective performance of the film is greatly improved.
Description
Technical field
The present invention relates to metallic surface and process, particularly a kind of magnesium alloy surface homogenization pretreatment process.
Background technology
Magnesium alloy is low owing to having density, and the casting that specific tenacity, specific rigidity are high and good and machinability etc. have a wide range of applications in fields such as aerospace, telecommunications, automobile making, defence and militaries.But the poor widespread use that restricts magnesium alloy of erosion resistance and wear resisting property.It is a kind of economy, quick and easy its corrosion resistance nature of raising and the method for wear resisting property that magnesium alloy is carried out to surface treatment.
Science and technology is looked into newly and patent search result shows, magnesium alloy is carried out to surface treatment, and at present most widely used is anodic oxidation, chemical conversion, electroless plating and electroplating technology.The key of magnesium alloy surface treatment is the magnesium alloy pre-treating technology.If pre-treating technology is suitable, once, after Mg alloy surface has successfully formed bottom, just can form the rete with property at Mg alloy surface, to be suitable for various Service Environment.Yet, magnesium alloy is polyphase structure often, this makes magnesium alloy is all inhomogeneous on chemical composition and electrochemistry, there is very large potential difference between matrix phase and second-phase, when magnesium alloy is placed in treatment solution, different meeting shows different electrochemical behaviors, two alternately also galvanic corrosion can occur, cause the rete formed each alternate there are differences, and the protection rete of Mg alloy surface is generally the cathodic rete, once partial failure is arranged, this will speed up the corrosion of magnesium alloy substrate, and this is also poorer than there is no protective layer.For example, AZ91D is typical duplex structure magnesium alloy, matrix phase α-Mg and second-phase β phase (Mg
17al
12) between have potential difference, when AZ91D being soaked to Zn and process, often be difficult to obtain satisfied effect, what on second-phase, obtain is loose often, bonding force is poor, discontinuous Zn layer; On the AZ91D magnesium alloy during chemical plating Mi-P alloy, Ni-P preferentially goes up forming core mutually at second-phase β, but the Ni-P alloy is mainly grown on α-Mg afterwards, and the defects such as pin hole mainly are gathered in second-phase β phase, once corrosion occurs from here on, will speed up the corrosion of magnesium alloy substrate.Equally, anode oxide film, the formation of chemical conversion film also is subject to the impact of matrix second-phase.
Therefore, people have carried out large quantity research to the magnesium alloy pre-treatment, to magnesium alloy, the most frequently used pre-treating process is at present: polishing → alkaline degreasing → chromic acid pickling → hydrofluoric acid activation, purpose is to remove the Mg alloy surface grease, in the time of oxide compound and oxyhydroxide, at Mg alloy surface, form the finer and close MgF of one deck
2film both can provide protective effect to magnesium alloy in subsequent disposal liquid, made the current potential of Mg alloy surface more even simultaneously.But chromic acid, hydrofluoric acid are very large to environmental hazard, and MgF
2the impact that film can not avoid the second-phase intermetallic compound to form subsequent film fully.
Summary of the invention
Purpose of the present invention, exactly for a kind of magnesium alloy surface homogenization pretreatment process is provided, to remove Mg alloy surface second-phase intermetallic compound, for magnesium alloy provides a chemical composition and the uniform preplating of electrochemistry surface.
To achieve these goals, the present invention has adopted following technical scheme: a kind of magnesium alloy surface homogenization pretreatment process, and described magnesium alloy is the Mg-Al alloy; Comprise the following steps:
A, polishing, polished to grease, oxide skin and corrosion product, the corner of Mg alloy surface, obtains clean fresh Mg alloy surface;
B, alkaline degreasing are processed, and preparation alkaline degreasing liquid, be placed in alkaline degreasing liquid by the clean magnesium alloy of polishing, processes 5-10min under 65-80 ℃, moderate agitation;
C, acidic activated processing, prepare acid activation solution, and the magnesium alloy that will process through alkaline degreasing is placed in acidic activated liquid, at room temperature processes 30-60s, moderate agitation;
D, alkalescence adjustment are processed, and the preparation alkaline adjustment liquid, will be placed in alkaline adjustment liquid through the magnesium alloy of acidic activated processing, process 5-30min under 65-80 ℃, moderate agitation;
Between above-mentioned each step, adopt flowing water to wash 3min in magnesium alloy.
Alkaline degreasing liquid described in step b is the aqueous solution formulated by sodium hydroxide, sodium phosphate, sodium carbonate and tensio-active agent, wherein the concentration of sodium hydroxide is 30-60g/L, the concentration of sodium phosphate is 5-15g/L, the concentration of sodium carbonate is 1-5g/L, and the concentration of tensio-active agent is 10-80mg/L.
Described tensio-active agent is selected from one or both in sodium laurylsulfonate, perfluoro octyl sulfonic acid tetraethyl-amine.
Acidic activated liquid described in step c is one or more the formulated aqueous solution in phosphoric acid, SODIUMNITRATE or citric acid, and wherein the concentration of phosphoric acid is 5-200mL/L, and the concentration of SODIUMNITRATE is 5-10g/L, and the concentration of citric acid is 50-100g/L.
Alkaline adjustment liquid described in steps d is the aqueous solution of sodium hydroxide, and the concentration of sodium hydroxide is 50-200g/L.
The present invention is directed to the present situation of current magnesium alloy pre-treating technology and the problem of existence, adopt environmental protection, cost is low, pre-treating technology easy and simple to handle, remove Mg alloy surface second-phase tissue, for the preplating magnesium alloy obtains a chemical composition and the uniform condition of surface of electrochemistry, and there is following advantage and disadvantage:
1, environmental protection, cost is low, easy to operate;
2, remove Mg alloy surface second-phase tissue fully, at Mg alloy surface, obtain chemical composition and the uniform preplating of electrochemistry surface, remove the disadvantageous effect that second-phase forms subsequent film;
3, suitability is wide, can be in conjunction with existing ripe surface treatment method, and the rete obtained is more even, densification, barrier propterty improves greatly.
The accompanying drawing explanation
Fig. 1, Fig. 2 are AZ91D Mg alloy surface back scattering SEM figure: wherein, Fig. 1 is for before processing, and Fig. 2 is for after processing;
Fig. 3 is that the AZ91D magnesium alloy surface chemical after pre-treating technology of the present invention is processed soaks the Zn layer;
Fig. 4 is the AZ91D magnesium alloy surface chemical plating Ni-P layer after pre-treating technology of the present invention is processed.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
Embodiment mono-:
A kind of AZ91D magnesium alloy surface homogenization pretreatment process, the AZ91D Mg alloy surface back scattering SEM figure before processing as shown in Figure 1.Comprise following steps:
1, magnesium alloy is polished to 1200#;
2, alkaline degreasing is processed: preparation alkaline degreasing liquid, comprise sodium hydroxide 60g/L in this liquid, and sodium phosphate 10g/L, sodium carbonate 5g/L, tensio-active agent 30mg/L, surplus is water.Wherein tensio-active agent is sodium laurylsulfonate.Water is distilled water or deionized water; Alkaline degreasing liquid is heated to 65 ℃, the magnesium alloy of polishing is put into to alkaline degreasing and wash 8min, moderate agitation;
3, acidic activated processing, prepare acid activation solution, comprises citric acid 100g/L in this liquid, and surplus is water, and water is distilled water or deionized water, will put into acidic activated liquid through the magnesium alloy of alkaline degreasing and wash 30s, and treatment temp is room temperature, moderate agitation;
4, alkalescence adjustment is processed, and the preparation alkaline adjustment liquid, comprise sodium hydroxide 200g/L in this liquid, and surplus is water, and alkaline adjustment liquid is heated to 65 ℃, the magnesium alloy after acid-wash activation is processed is put into to alkaline adjustment liquid and wash 5min, moderate agitation;
Between each step, adopt flowing water to wash 3min.
Through SEM and EDXS, analyze, through the AZ91D Mg alloy surface second-phase Mg of above-mentioned processing
17al
12be removed, surface composition is even, and the AZ91D Mg alloy surface back scattering SEM figure after processing as shown in Figure 2.To be soaked Zn to the magnesium alloy through above-mentioned processing and process, the Zn layer obtained is even, densification, and fraction of coverage is high, as shown in Figure 3.
Embodiment bis-:
A kind of AZ91D magnesium alloy surface homogenization pretreatment process comprises following steps:
1, magnesium alloy is polished to 1200#;
2, alkaline degreasing is processed: preparation alkaline degreasing liquid, comprise sodium hydroxide 60g/L in this liquid, and sodium phosphate 10g/L, sodium carbonate 5g/L, tensio-active agent 10mg/L, surplus is water.Wherein tensio-active agent is perfluoro octyl sulfonic acid tetraethyl-amine, and water is distilled water or deionized water; Alkaline degreasing liquid is heated to 70 ℃, the magnesium alloy of polishing is put into to alkaline degreasing and wash 8min, moderate agitation;
3, acidic activated processing, prepare acid activation solution, comprises citric acid 100g/L in this liquid, and surplus is water, and water is distilled water or deionized water, will put into pickle solution through the magnesium alloy of alkaline degreasing and wash 45s, and treatment temp is room temperature, moderate agitation;
4, alkalescence adjustment is processed, and the preparation alkaline adjustment liquid, comprise sodium hydroxide 100g/L in this liquid, and surplus is water; Alkaline adjustment liquid is heated to 70 ℃, the magnesium alloy after acid-wash activation is processed is put into to alkaline adjustment liquid and wash 30min, moderate agitation;
Between each step, adopt flowing water to wash 3min.
Through SEM and EDXS, analyze, through the AZ91D Mg alloy surface second-phase Mg of above-mentioned processing
17al
12be removed, surface composition is even.To carry out the chemical Ni-P plating processing to the magnesium alloy through above-mentioned processing, the Ni-P layer obtained is even, densification, and barrier propterty is high, as shown in Figure 4.
Claims (2)
1. a magnesium alloy surface homogenization pretreatment process, described magnesium alloy is the Mg-Al alloy; It is characterized in that, comprise the following steps:
A, polishing, polished to grease, oxide skin and corrosion product, the corner of Mg alloy surface, obtains clean fresh Mg alloy surface;
B, alkaline degreasing are processed, and preparation alkaline degreasing liquid, be placed in alkaline degreasing liquid by the clean magnesium alloy of polishing, processes 5-10min under 65-80 ℃, moderate agitation;
C, acidic activated processing, prepare acid activation solution, and the magnesium alloy that will process through alkaline degreasing is placed in acidic activated liquid, at room temperature processes 30-60s, moderate agitation;
D, alkalescence adjustment are processed, and the preparation alkaline adjustment liquid, will be placed in alkaline adjustment liquid through the magnesium alloy of acidic activated processing, process 5-30min under 65-80 ℃, moderate agitation;
Between above-mentioned each step, adopt flowing water to wash 3min in magnesium alloy;
Alkaline degreasing liquid described in step b is the aqueous solution formulated by sodium hydroxide, sodium phosphate, sodium carbonate and tensio-active agent, wherein the concentration of sodium hydroxide is 30-60g/L, the concentration of sodium phosphate is 5-15g/L, the concentration of sodium carbonate is 1-5g/L, and the concentration of tensio-active agent is 10-80mg/L;
Acidic activated liquid described in step c is one or more the formulated aqueous solution in phosphoric acid, SODIUMNITRATE or citric acid, and wherein the concentration of phosphoric acid is 5-200mL/L, and the concentration of SODIUMNITRATE is 5-10g/L, and the concentration of citric acid is 50-100g/L;
Alkaline adjustment liquid described in steps d is the aqueous solution of sodium hydroxide, and the concentration of sodium hydroxide is 50-200g/L.
2. magnesium alloy surface homogenization pretreatment process as claimed in claim 1, it is characterized in that: described tensio-active agent is selected from one or both in sodium laurylsulfonate, perfluoro octyl sulfonic acid tetraethyl-amine.
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| CN103757614B (en) * | 2014-01-02 | 2016-08-17 | 上海交通大学 | A kind of coating of magnesium and magnesium alloy and preparation method thereof |
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| CN108456884B (en) * | 2017-02-21 | 2019-10-22 | 中国科学院金属研究所 | A kind of pre-treating method of magnesium alloy chromium-free conversion film homogenization |
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| CN1207440C (en) * | 2003-07-10 | 2005-06-22 | 上海交通大学 | Zinc-impregnating layer anodic oxidation method colouring process and its treatment solution formula |
| CN101451239B (en) * | 2007-11-29 | 2010-12-22 | 比亚迪股份有限公司 | Chemical conversion treatment fluid and treatment method of magnesium alloy surface |
| KR101067743B1 (en) * | 2009-11-18 | 2011-09-28 | 한국생산기술연구원 | Anodizing surface treatments method of magnesium or magnesium alloy |
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| CN103757614B (en) * | 2014-01-02 | 2016-08-17 | 上海交通大学 | A kind of coating of magnesium and magnesium alloy and preparation method thereof |
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