Study of Compactness of Micro-Arc Oxidation Coating Treated by Laser Surface Melting on TC4 Surface

摘要

In view of the micro-arc oxidation (MAO) coating with loose surface, big micropore and porosity has mechanical properties shortcomings. Three kinds of MAO coating were prepared on TC4 alloy in electrolyte and treated by laser surface melting (LSM) with various power density. Compactness of the coatings was analyzed based on the SEM images. The results showed that the porosity and the average diameter of pores were decreased, and a compact remelting layer was formed in the MAO + LSM coatings. On the discontinuous smelting surface of MAO + LSM coating, pores are often found in the individual melting micro-area. The most of molten pools originated in the pore of MAO coating surface, then as the laser energy being absorbed continually, the discrete melted areas would grew and finally expended into continuous melted areas. The content of anatase increased after the LSM treatment especially under low scanning speed of laser beam. The average hardness of MAO + LSM coatings is almost twice as hard as MAO coating. Conclude: to improve mechanical properties shortcomings of TC4 micro-arc oxidation coating, Laser remelting secondary modification process has played a positive role.