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Method for preparing composite nickel coating on surface of magnesium alloy micro-arc oxidation film

A micro-arc oxidation and magnesium alloy technology, applied in the field of metal surface treatment, can solve the problems of deterioration of mechanical properties of magnesium alloy parts, difficulty in obtaining uniform defect-free coating, bimetallic galvanic corrosion, etc., to improve the overall protection performance and bonding performance. , Low toxicity and environmental protection of materials, and the effect of high bonding strength

Inactive Publication Date: 2014-04-02
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the magnesium alloy ceramic film has a porous structure, and electroless plating is performed directly on its surface. Since the plating metal has a higher potential than the magnesium alloy, bimetallic galvanic corrosion is prone to occur after contacting the magnesium alloy.
Especially for complex shapes or large-area plated parts, it is difficult to obtain uniform and defect-free coatings
The formation of such structural defects is prone to local bimetallic corrosion or microscopic galvanic corrosion, resulting in the deterioration of the mechanical properties of magnesium alloy parts, which will greatly accelerate the corrosion process and cause disastrous consequences.
Moreover, in the process of direct electroless nickel plating on the surface of magnesium alloy substrate, F - and Cr 6+ , or use palladium salt activation, which not only causes pollution and damage to the environment, but also increases the cost, which is not conducive to engineering production

Method used

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  • Method for preparing composite nickel coating on surface of magnesium alloy micro-arc oxidation film
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  • Method for preparing composite nickel coating on surface of magnesium alloy micro-arc oxidation film

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] 1. Material preparation: After AZ91D magnesium alloy is cut, polished and polished, use ultrasonic cleaning in acetone solution to remove oil, and then ultrasonic cleaning in deionized water to remove organic matter and impurities.

[0037] 2. Micro-arc oxidation: In the electrolyte, sodium silicate is 15g / L, sodium hydroxide is 2g / L, sodium carbonate is 5g / L, the rest is water, and the temperature is 50°C; high-voltage pulse method is used for micro-arc oxidation, pulse Frequency is 500Hz, current density is 2A / dm 2 , the oxidation time is 40 minutes, and the thickness of the oxide film is 25 μm. The oxide film is a porous ceramic membrane with a porosity of 40% and a pore diameter of 2 to 5 μm.

[0038] 3. Sealing and nickel plating treatment

[0039] 1) Configuration of silane mixture. Mix and stir silane KH-560 and TEOS at a molar ratio of n(KH560):n(TEOS)=3:1 to obtain a silane mixture.

[0040] 2) The configuration of the hydrolysis catalyst. Acetic acid and p...

Embodiment 2

[0053] The difference from Example 1 is:

[0054] 1. Material preparation: After the AZ31B magnesium alloy is cut, polished and polished, it is cleaned and degreased by ultrasonic cleaning in absolute ethanol solution, and then organic matter and impurities are removed by ultrasonic cleaning in deionized water.

[0055] 2. Micro-arc oxidation: In the electrolyte, sodium silicate is 10g / L, sodium hydroxide is 10g / L, sodium carbonate is 8g / L, the rest is water, and the temperature is 35°C. Micro-arc oxidation is carried out by high-voltage pulse method, the pulse frequency is 800Hz, and the current density is 2A / dm 2 , the oxidation time is 60min, and the thickness of the oxide film is 15μm. The oxide film is a porous ceramic membrane with a porosity of 35% and a pore size of 3-5μm.

[0056] 3. Sealing and nickel plating treatment

[0057] 1) Configuration of silane mixture. Mix and stir the silane KH-560 and TEOS at a molar ratio of n(KH560):n(TEOS)=3:2 to obtain a silane mi...

Embodiment 3

[0071] The difference from Example 1 is:

[0072] 1. Material preparation: After cutting, grinding and polishing the ZM5 magnesium alloy, use ultrasonic cleaning in organic solvent to remove oil, and then ultrasonic cleaning in deionized water to remove organic matter and impurities.

[0073] 2. Micro-arc oxidation: In the electrolyte, sodium silicate is 20g / L, sodium hydroxide is 6g / L, sodium carbonate is 8g / L, and the rest is water. 1000Hz, current density 3A / dm 2 , the oxidation time is 50 minutes, and the thickness of the oxide film is 20 μm. The oxide film is a porous ceramic film with a porosity of 50% and a pore diameter of 6-10 μm.

[0074] 3. Sealing and nickel plating treatment

[0075] 1) Configuration of silane mixture. Mix and stir silane KH-560 and TEOS at a molar ratio of n(KH560):n(TEOS)=5:2 to obtain a silane mixture.

[0076] 2) The configuration of the hydrolysis catalyst. Acetic acid and phytic acid are uniformly mixed in a molar ratio of n(acetic acid...

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Abstract

The invention discloses a method for preparing a composite nickel coating on the surface of a magnesium alloy micro-arc oxidation film, and belongs to the technical field of metal surface treatment. The method comprises the following steps: putting a magnesium alloy matrix in a silicate series electrolyte to prepare a micro-arc oxidation ceramic layer, carrying out surface hole sealing and pre-nickeling treatment of the matrix ceramic layer by adopting a nickel salt-containing self-assembled nano-penetrant and an alcoholic solution of sodium borohydride, and carrying out composite chemical nickeling treatment to form the composite nickel coating on the surface of the film. The method is an improvement on tradition chemical nickeling technologies, and adopts a palladium salt-free activation process at room temperature, so the composite chemical nickeling operation is simplified, and the pollution of the process to the environment is reduced. The prepared composite coating has the advantages of good protection thickness, good bonding force with the substrate, good corrosion resistance, high hardness, good surface brightness, shininess, effective solving of the protection requirements on the high wear resistance and the corrosion resistance of a magnesium alloy, and provision of a powerful guarantee for the further application of the magnesium alloy.

Description

technical field [0001] The invention relates to a method for preparing a composite nickel plating layer on the surface of a magnesium alloy micro-arc oxidation film, belonging to the technical field of metal surface treatment. Background technique [0002] Magnesium alloy is the metal with the lowest density among metal structural materials. Compared with aluminum alloy, it has a large elastic modulus, good heat dissipation, good shock absorption, and large impact load capacity. The metal structure material with the most potential for performance optimization development is also one of the most promising metal materials in the 21st century. In addition, magnesium alloy also has superior properties such as high specific strength, high specific stiffness, good damping, good thermal conductivity and good vibration damping. As a substitute for steel, aluminum, plastic and other materials, it is widely used in the automotive industry, aerospace industry and electronics. Industry...

Claims

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Application Information

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IPC IPC(8): C23C28/00
Inventor 杜克勤郭兴华王艳秋王勇郭泉忠王福会
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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