Effect of Laser Remelting Treatment on Microstructure and Properties of Aluminum Alloy Micro-arc Oxidation Coatings

Abstract

The coating was treated by laser with different power. Microstructures of two kinds of coatings were examined by scanning electron microscopy(SEM). The phase of two kinds of coatings was detected by X-ray diffraction(XRD). The micro hardness of the coatings was tested by micro hardness tester. Corrosion resistance of the coatings was evaluated by electrochemical workstation. Wear resistance of the coatings was detected by friction and wear test. The results show that micro-arc oxidation coating is remelted by laser treatment, the coating is more dense after being remelted and cooling.The coating after laser treatment is still composed of γ-Al2O3 phase. Part of γ-Al2O3 in the coating is transformed to α-Al2O3. With the increase of laser power, micro hardness of the coating firstly increases and then decreases. When the laser power is 150W, the micro hardness is the maximum, which is 625HV. The electrochemical measurements show that corrosion potential of the coating is shifted to -0.577V and corrosion current density reduces significantly to 3.903×10-6A/cm2 after 150W laser treatment. The friction and wear experiments show that the surface of the coating appears spalling phenomenon. Friction and wear loss is about 1/323 of the substrate.

Keywords

• aluminum alloy
• micro-arc oxidation
• laser remelting treatment
• compactness
• corrosion resistance
• wear resistance