CN109853022A - A kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy - Google Patents
A kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy Download PDFInfo
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- CN109853022A CN109853022A CN201910215152.6A CN201910215152A CN109853022A CN 109853022 A CN109853022 A CN 109853022A CN 201910215152 A CN201910215152 A CN 201910215152A CN 109853022 A CN109853022 A CN 109853022A
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Abstract
Invention describes a kind of preparation methods of Mg-Al hydrotalcite/differential arc oxidation composite coating, by being pre-processed to aluminum alloy differential arc oxidation, then 5 ~ 10min is impregnated in the magnesium nitrate hexahydrate and ammonium nitrate mixed solution of alkalinity, then 12 ~ hydro-thermal reaction for 24 hours is carried out at a temperature of 100 DEG C ~ 200 DEG C, it finally opens reaction kettle and takes out sample, it is cleaned with deionized water, is dry, high anti-corrosion Mg-Al LDH/MAO composite coating is prepared on the surface of aluminium alloy.To form magnalium hydrotalcite coating on the surface of aluminum alloy differential arc oxidation layer.Obtained magnalium hydrotalcite coating has excellent impedance modulus, can not only effectively repair the hole and crackle of differential arc oxidation layer, and can adsorb the anion in etchant solution well, be obviously improved the corrosion resistance of alloy.In addition, present invention process is simple and easy to operate, at low cost, environmental protection has the feasibility being widely popularized.
Description
Technical field
The present invention relates to aluminum alloy surface processing techniques, and in particular to a kind of anti-corrosion Mg-Al LDH/MAO of aluminium alloy is compound
The preparation method of coating.
Background technique
2024 aluminium alloys the excellent properties such as are not easy to soften and are widely used in airframe and company when having intensity high, high temperature
On fitting, but since its corrosion resisting property is poor, its development is usually limited, so, in order to promote the corrosion resistance of aluminium alloy,
It needs to be surface-treated it.Currently, common surface treatment or not enough environmental protection such as plating and chemical plating, chemistry
Conversion processing and organic polymer painting treatment or the not enough densification of preparation gained surface covering there are a large amount of hole and lack
It falls into, such as anodized and differential arc oxidation.Compared to other technologies, micro-arc oxidation of aluminum alloy surface is more advanced at present
And the process for treating surface of environmental protection, the ceramic layer of this method preparation have good corrosion resistance and heat resistance.Differential arc oxidation preparation
Gained ceramic layer is generally made of weaker zone, transition zone and compacted zone, due to intensive and continual electric spark and thermal stress,
It can be the defects of forming many holes and micro-crack on weaker zone, corrosive medium can enter matrix by these defects, to aluminium
Alloy substrate carries out corrosion failure, these defects significantly reduce the anti-corrosion protective effect of the coating.Based on this problem, by repairing
Multiple differential arc oxidation coating can promote the corrosion resistance of aluminium alloy.
Layered double hydroxide (LDHs) structure be ordered by two-dimentional laminate longitudinal arrangement at three-dimensional crystalline structure.Layer
By Covalent bonding together in plate, pass through the connection such as ionic bond, hydrogen bond between layers.Structure of the LDHs structure based on shepardite,
On Layered compound, bivalent cation is replaced and positively charged by Tricationic, and the anion of interlayer and laminate positive electricity phase
Balancing chemical composition is usually [M2+ 1-xM3+ x(OH)2]x+(AN-)x/n·y H2O, M are cation, and A is anion, x M3+/( M3+
+ M2+) the mass ratio of the material, y be hydrone number.LDHs coating is formed in aluminum alloy surface, LDHs coating is by positively charged
What the anion between laminate and laminate formed, the anion of interlayer has interchangeability, due to anion interchangeability, Cl?
Anion exchange with interlayer and be present in interlayer, it is suppressed that Cl?Destruction to aluminum alloy surface protective coating, it is effective to be promoted
The corrosion resisting property of aluminium alloy.
The characteristic of defect and layered double hydroxide (LDHs) based on aluminium alloy tradition differential arc oxidation coating (MAO),
The present invention proposes a kind of preparation method of Mg-Al hydrotalcite/differential arc oxidation composite coating (Mg-Al LDH/MAO), not only passes through
Micropore and micro-crack that Mg-Al stratiform hydrotalcite repairs differential arc oxidation rear surface are generated, and utilizes the Mg-Al stratiform hydrotalcite
Suction-operated reduce such as Cl of the anion in corrosive medium-, can effectively promote the corrosion resistance of aluminium alloy.Benefit of the invention
Mg-Al hydrotalcite coating is formed in micro-arc oxidation ceramic layer with hydro-thermal method, the corrosion resistance of aluminium alloy can be significantly improved.It should
Simple process is easy to operate, at low cost, and environmental protection has the feasibility being widely popularized.
Summary of the invention
The purpose of the present invention is to provide a kind of preparation methods of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy.This
Invention prepares Mg-Al LDH/MAO composite coating in aluminum alloy surface using a kind of simple and environmentally-friendly method, can be to differential of the arc oxygen
The ceramic layer defects of change are repaired, and the composite coating can also reduce the Cl- in etchant solution by interaction suction-operated
Ion concentration, to significantly improve the corrosion resistance of aluminium alloy.
To achieve the above object, the present invention adopts the following technical scheme:
A kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy, comprising the following steps:
(1) it pre-processes: aluminium alloy being ground, polish, deoil, is dried；
(2) differential arc oxidation: pretreated aluminium alloy is subjected to differential arc oxidation using constant current mode, the processing time is 10-
15min, frequency 800Hz；
(3) by the sample after step (2) differential arc oxidation be put into containing magnesium nitrate hexahydrate and ammonium nitrate and with the ammonium hydroxide tune of 1wt%
It saves in the mixed solution that its pH is 8-12 and impregnates 5-10min；
(4) sample after immersion is subjected to hydro-thermal reaction in water heating kettle；
(5) sample after step (4) hydro-thermal reaction is cleaned with deionized water, is dry, i.e., be prepared on the surface of aluminium alloy
High anti-corrosion Mg-Al LDH/MAO composite coating.
The constituent of electrolyte used in step (2) described differential arc oxidation are as follows: sodium metasilicate 20g/L, sodium phosphate 10g/L, hydrogen
Sodium oxide molybdena 2g/L.
The final concentration of 0.1-0.5mol/L of magnesium nitrate hexahydrate, the end of ammonium nitrate are dense in step (3) described mixed solution
Degree is 0.4-0.8mol/L.
The temperature of step (4) described hydro-thermal reaction is 100 DEG C ~ 200 DEG C, reaction time 12-24h.
Further, above-mentioned preparation method is applied in the preparation of corrosion resistance aluminium alloy.
The present invention has the advantages that
(1) present invention prepares resulting Mg-Al LDH/MAO composite coating, and it is micro- that the LDHs in the composite coating not only repairs tradition
Arc aoxidizes the micropore and micro-crack of rear surface ceramic layer, and LDHs is by the anion group between positively charged laminate and laminate
At, the anion of interlayer has interchangeability, due to anion interchangeability, Cl?Anion exchange with interlayer and exist
In interlayer, it is suppressed that Cl in etchant solution?Destruction to alloy surface coating effectively improves the corrosion resisting property of alloy.
(2) present invention not only improves in the method for the high anti-corrosion Mg-Al LDH/MAO composite coating of aluminum alloy surface preparation
The performance of traditional differential arc oxidation coating, and this method is efficient, inexpensive, process is simple, no pollution to the environment, can significantly mention
High-aluminium alloy corrosion resistance widens aluminium alloy application range.
(3) Mg-Al LDH/MAO composite coating of the present invention has the characteristic of stratiform hydrotalcite coating, can be used as a kind of suction
Attached coating.
(4) present invention process is simple and environmentally-friendly, significantly improves the corrosion resistance of aluminium alloy, increases the service life of alloy.
Detailed description of the invention
Fig. 1 is the sample SEM morphology analysis figure before and after forming Mg-Al LDHs/MAO composite coating, wherein (a) is the differential of the arc
Sample is aoxidized, (b) in pH value of solution=9, t=for 24 hours, Mg-Al LDHs/MAO composite coating obtained at T=180 DEG C.
Fig. 2 is the sample polarization curve to be formed before and after Mg-Al LDHs/MAO composite coating.
Fig. 3 is that reaction temperature is that the sample EDS analysis of Mg-Al LDHs/MAO composite coating is formed at 180 DEG C.
Fig. 4 is the sample XRD analysis to be formed before and after Mg-Al LDHs/MAO composite coating.
Fig. 5 is that various sample corrodes the EDS figure after 144h in 1M NaCl solution, wherein (a) is that only differential arc oxidation applies
Layer sample, (b) in pH value of solution=9, t=for 24 hours, Mg-Al LDHs/MAO composite coating obtained at T=180 DEG C.
Specific embodiment
Embodiment 1
(1) aluminium alloy such as is ground, is polished, being deoiled, being dried at the pretreatment；
(2) aluminium alloy after polishing is subjected to differential arc oxidation；The constituent of electrolyte used in differential arc oxidation are as follows: sodium metasilicate 20g/
L, sodium phosphate 10g/L, sodium hydroxide 2g/L；Differential arc oxidation uses constant current mode, and the processing time is 10min, and frequency is
800Hz；
(3) differential arc oxidation sample is put into the ammonium nitrate of magnesium nitrate hexahydrate containing 0.1mol/L, 0.6mol/L, and with the ammonia of 1wt%
Water, which is adjusted in the mixed solution that pH is 9, impregnates 10min；
(4) sample after immersion is subjected to hydro-thermal reaction in water heating kettle, reaction temperature is 180 DEG C, and the reaction time is for 24 hours；
(5) it finally opens reaction kettle and takes out sample, cleaned with deionized water, is dry, be prepared in this way on the surface of aluminium alloy
High anti-corrosion Mg-Al LDH/MAO composite coating.
Embodiment 2
(1) aluminium alloy such as is ground, is polished, being deoiled, being dried at the pretreatment；
(2) aluminium alloy after polishing is subjected to differential arc oxidation；The constituent of electrolyte used in differential arc oxidation are as follows: sodium metasilicate 20g/
L, sodium phosphate 10g/L, sodium hydroxide 2g/L；Differential arc oxidation uses constant current mode, and the processing time is 10min, and frequency is
800Hz；
(3) differential arc oxidation sample is put into the ammonium nitrate of magnesium nitrate hexahydrate containing 0.2mol/L, 0.6mol/L, and with the ammonia of 1wt%
Water, which is adjusted in the mixed solution that pH is 10, impregnates 10min；
(4) sample after immersion is subjected to hydro-thermal reaction in water heating kettle, reaction temperature is 125 DEG C, and the reaction time is for 24 hours；
(5) it finally opens reaction kettle and takes out sample, cleaned with deionized water, is dry, be prepared in this way on the surface of aluminium alloy
High anti-corrosion Mg-Al LDH/MAO composite coating.
Embodiment 3
(1) aluminium alloy such as is ground, is polished, being dried at the pretreatment；
(2) aluminium alloy after polishing is subjected to differential arc oxidation；The constituent of electrolyte used in differential arc oxidation are as follows: sodium metasilicate 20g/
L, sodium phosphate 10g/L, sodium hydroxide 2g/L；Differential arc oxidation uses constant current mode, and the processing time is 10min, and frequency is
800Hz；
(3) differential arc oxidation sample is put into the ammonium nitrate of magnesium nitrate hexahydrate containing 0.1mol/L, 0.5mol/L, and with the ammonia of 1wt%
Water, which is adjusted in the mixed solution that pH is 12, impregnates 5min；
(4) sample after immersion is subjected to hydro-thermal reaction in water heating kettle, reaction temperature is 200 DEG C, and the reaction time is for 24 hours；
(5) it finally opens reaction kettle and takes out sample, cleaned with deionized water, is dry, be prepared in this way on the surface of aluminium alloy
High anti-corrosion Mg-Al LDH/MAO composite coating.
Comparative example
(1) aluminium alloy such as is ground, is polished, being deoiled, being dried at the pretreatment；
(2) aluminium alloy after polishing is subjected to differential arc oxidation；The constituent of electrolyte used in differential arc oxidation are as follows: sodium metasilicate 20g/
L, sodium phosphate 10g/L, sodium hydroxide 2g/L；Differential arc oxidation uses constant current mode, and the processing time is 10min, and frequency is
800Hz；
(3) sample after differential arc oxidation is cleaned with deionized water, is dry.
Coating made from embodiment 1 and comparative example is subjected to SEM characterization, the result is shown in Figure 1, wherein (a) figure is differential arc oxidation
The shape appearance figure of sample finds its surface there are a large amount of hole, and more uniform distribution, (b) figure is the sample that reaction temperature is 180 DEG C
The shape appearance figure of product, it can be seen that form more LDHs, distribution uniform on surface, and growth is more complete, present apparent
Laminated structure, pore quantity are reduced.
It was found from forming the sample polarization curve (Fig. 2) before and after Mg-Al LDHs/MAO composite coating, it can be seen that 180 DEG C
When sample compared to original sample, corrosion current is smaller, and corrosion potential is higher, better corrosion resistance is presented, from polarization curve
It can be seen that coming, slope of a curve is very big at 180 DEG C, shows that its resistance coefficient is higher, good passivation effect, i.e. corrosion resisting property compared with
It is good.
By the EDS map (Fig. 3) of composite coating it is found that micro-arc oxidation ceramic layer main component is aluminium oxide, so Al
It is relatively uniform with the component distributing of O, it is also more；And LDH solution is Mg (NO3)2·6H2O, so Mg can be used as to form LDHs
The index of coating, Mg is distributed very uniform at this time, and Mg content is relatively high at this time, and it is more to illustrate that sample surfaces generate
LDHs coating.Wherein Si element may be due to introducing from electrolyte during micro-arc oxidation treatment.
By the X-ray map (Fig. 4) of composite coating it is found that by 180 DEG C of sample curves and differential arc oxidation sample curve comparison, very
It can clearly be seen that additionally there is 1 peak at 12 degree and 14 degree or so at 180 DEG C.The appearance at these peaks shows in sample table
Face forms LDHs coating.
After the sample of embodiment 1 and comparative example 1 corrodes 144h in 1M NaCl solution, EDS map is shown in Fig. 5, wherein
It (a) be differential arc oxidation sample (b) is in pH value of solution=9, t=for 24 hours, the compound painting of magnalium hydrotalcite/differential arc oxidation obtained at T=180 DEG C
Layer.By comparison, it was found that pH=9, T=180 DEG C have scanned Cl element after corroding under the conditions of t=for 24 hours, have shown that the LDHs generated is applied
Layer is due to there is the ability of anion exchange, when being immersed in NaCl solution, the NO of interlayer- 3With the Cl in solution-It is exchanged,
So that corrosive ions Cl-Into hydrotalcite layers, inhibit Cl-Destruction to coating, to improve the corrosion resistance of coating.
The foregoing is merely presently preferred embodiments of the present invention, all equivalent changes done according to scope of the present invention patent with
Modification, is all covered by the present invention.
Claims (5)
1. a kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy, which comprises the following steps:
(1) it pre-processes: aluminium alloy being ground, polish, deoil, is dried；
(2) differential arc oxidation: pretreated aluminium alloy is subjected to differential arc oxidation using constant current mode, the processing time is 10-
15min, frequency 800Hz；
(3) by the sample after step (2) differential arc oxidation be put into containing magnesium nitrate hexahydrate and ammonium nitrate and with the ammonium hydroxide tune of 1wt%
It saves in the mixed solution that its pH is 8-12 and impregnates 5-10min；
(4) sample after immersion is subjected to hydro-thermal reaction in water heating kettle；
(5) sample after step (4) hydro-thermal reaction is cleaned with deionized water, is dry, i.e., be prepared on the surface of aluminium alloy
High anti-corrosion Mg-Al LDH/MAO composite coating.
2. a kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy, feature exist according to claim 1
In the constituent of electrolyte used in step (2) described differential arc oxidation are as follows: sodium metasilicate 20g/L, sodium phosphate 10g/L, sodium hydroxide
2g/L。
3. a kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy, feature exist according to claim 1
In, the final concentration of 0.1-0.5mol/L of magnesium nitrate hexahydrate in step (3) described mixed solution, ammonium nitrate it is final concentration of
0.4-0.8mol/L 。
4. special according to a kind of preparation method of the anti-corrosion Mg-Al LDH/MAO composite coating of aluminium alloy according to claim 1
Sign is that the temperature of step (4) described hydro-thermal reaction is 100 DEG C ~ 200 DEG C, reaction time 12-24h.
5. a kind of preparation method as described in claim 1-4 is any is in the application prepared in corrosion resistance aluminium alloy.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112899752A (en) * | 2020-12-18 | 2021-06-04 | 天津理工大学 | Method for preparing MAO-LDH coating with corrosion resistance and antibacterial property on surface of medical magnesium alloy and application |
| CN115948784A (en) * | 2023-02-01 | 2023-04-11 | 南京工程学院 | Magnesium alloy surface self-repairing coating and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2011116788A1 (en) * | 2010-03-25 | 2011-09-29 | Saint Petersburg State University | Layered titanates |
| CN105018999A (en) * | 2015-07-09 | 2015-11-04 | 哈尔滨工程大学 | Method for growing layered doubled hydroxide on aluminum alloy micro-arc oxidation film in situ |
| CN106400079A (en) * | 2016-11-16 | 2017-02-15 | 北京石油化工学院 | Preparation method of multiple super-hydrophobic composite film layers on aluminium alloy surface |
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2019
- 2019-03-21 CN CN201910215152.6A patent/CN109853022A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011116788A1 (en) * | 2010-03-25 | 2011-09-29 | Saint Petersburg State University | Layered titanates |
| CN105018999A (en) * | 2015-07-09 | 2015-11-04 | 哈尔滨工程大学 | Method for growing layered doubled hydroxide on aluminum alloy micro-arc oxidation film in situ |
| CN106400079A (en) * | 2016-11-16 | 2017-02-15 | 北京石油化工学院 | Preparation method of multiple super-hydrophobic composite film layers on aluminium alloy surface |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112899752A (en) * | 2020-12-18 | 2021-06-04 | 天津理工大学 | Method for preparing MAO-LDH coating with corrosion resistance and antibacterial property on surface of medical magnesium alloy and application |
| CN115948784A (en) * | 2023-02-01 | 2023-04-11 | 南京工程学院 | Magnesium alloy surface self-repairing coating and preparation method and application thereof |
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Application publication date: 20190607 |