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Two-step micro-arc oxidation method for producing super wear-resistant coating on surface of aluminium alloy

A technology of micro-arc oxidation on the surface of aluminum alloy, applied in the field of electrochemistry, can solve the problems of slow film formation speed, low corundum composition, affecting the wear resistance of the film layer, etc., and achieve the effect of fast film formation speed

Active Publication Date: 2014-05-28
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] 1. At present, the micro-arc oxidation of aluminum alloys at home and abroad mostly uses silicate as the electrolyte, and the corundum (α-Al 2 o 3 ) composition is low, and other impurity components with lower hardness (such as mullite) will be introduced into the film layer
[0011] 2. At present, the micro-arc oxidation treatment of most aluminum alloys at home and abroad is a low-concentration electrolyte, and the film-forming speed is slow
[0012] 3. The film layer obtained in low-concentration electrolyte (whether it is silicate or aluminate) has a double-layer structure, and there are large-sized holes in the inner and outer layers, which affects the wear resistance of the film layer
[0013] 4. The problem that aluminum alloys cannot be formed into films by conventional methods in high-concentration aluminate solutions

Method used

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  • Two-step micro-arc oxidation method for producing super wear-resistant coating on surface of aluminium alloy
  • Two-step micro-arc oxidation method for producing super wear-resistant coating on surface of aluminium alloy
  • Two-step micro-arc oxidation method for producing super wear-resistant coating on surface of aluminium alloy

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Embodiment 1

[0055] Example 1: two-step micro-arc oxidation

[0056] 1. Use E-44 epoxy resin to seal the area outside the working surface of the aluminum alloy substrate, polish the working surface of the aluminum alloy substrate with 60# to 2000# SiC sandpaper, and rinse the working surface with alcohol and deionized water respectively.

[0057] 2. One-step micro-arc oxidation treatment: use the substrate as the anode and the steel plate as the cathode, turn on the power, set the parameters of the micro-arc oxidation power supply, and the positive current is 25A / dm 2 , the negative current is set to (20) A / dm 2 , The positive and negative duty cycle is set to 20%, and the frequency is maintained at 1000Hz. The one-step electrolyte is composed of sodium aluminate and potassium hydroxide solution, wherein the concentration of aluminate is 10 g / L, and the concentration of potassium hydroxide is 1 g / L; after about 40 seconds of electrolysis (at this time, the cell voltage rises to about 45...

Embodiment 2

[0080] According to the method of embodiment 1, others are the same as embodiment 1, the parameter of micro-arc oxidation power supply is: positive current is 10A / dm 2 , the negative current is set to 10 A / dm 2 , the positive and negative duty cycle is set to 60%, the frequency is 500Hz, and NaAlO is used as described in the two-step micro-arc oxidation treatment 2 , = concentration is 45 g / L, treatment time is 5 min, the film thickness reaches 40 microns, the growth rate of the film layer increases, and the α-Al in the film 2 o 3 The content reaches 48%. The wear resistance can withstand the condition of 100 N friction time for 60 minutes.

Embodiment 3

[0082] According to the method of embodiment 1, others are the same as embodiment 1, and the current parameter is: the positive current is 40A / dm 2 , the negative current is set to 40A / dm 2 , The positive and negative duty cycle is set to 40%, and the frequency is 2000Hz; NaAlO is used as described in the two-step micro-arc oxidation treatment 2 , the concentration was 60 g / L, the treatment time was 5 min, the film thickness reached 50 microns, the growth rate of the film layer was further increased, and the α-Al in the film 2 o 3 content up to 55%. The wear resistance can also withstand the condition of 120 N rubbing time for 60 min.

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Abstract

The invention relates to the field of electrochemistry, and discloses a two-step micro-arc oxidation method for producing a super wear-resistant coating on the surface of an aluminium alloy. The method uses the aluminium alloy as a base body and uses the low-concentration and high-concentration aluminate solutions as mediums, and an aluminium oxide layer with a compact single layer structure is quickly formed through the two-step micro-arc oxidation, wherein the content of a corundum (alpha-Al2O3) component is more than 40%. A film with the thickness of about 40 to 50 micrometers can be formed only needing 8 to 10 min of the micro-arc oxidation. The film has excellent wear resistance, for the film with the thickness of about 40 to 50 micrometers, under the ball-block type dry friction condition, the wear of the film is just slight when being subjected to friction with load of 80 N for 30 min (the depth of the wearing scratch is 12 micrometers), and for the silicate micro-arc oxidation film taken as comparison, under the condition with the load of 80 N, the film can be worn after 5 min of friction, and the depth of the friction scratch reaches 109 micrometers.

Description

technical field [0001] The invention relates to the field of electrochemistry, in particular to a two-step micro-arc oxidation method for forming a super wear-resistant coating on the surface of an aluminum alloy. Background technique [0002] Aluminum is the most abundant metal element in the earth's crust, and it is also a type of metal element closely related to people. Various types of deformed aluminum alloys are used in space shuttles, missiles, cars, and mobile phone cases. Aluminum and its aluminum alloys have the advantages of high specific strength, good thermal and electrical conductivity, strong reflective properties, beautiful color, non-magnetic, good corrosion resistance, good plasticity and formability, and no low-temperature brittleness. non-ferrous metal materials. [0003] Aluminum and its aluminum alloys are widely used in various sectors of the country's economy due to their excellent properties, and have become the second largest metal material after s...

Claims

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Application Information

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IPC IPC(8): C25D11/12
Inventor 程英亮曹金晖彭昭美
Owner HUNAN UNIV
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