Characteristics of micro-arc oxidation and laser melting modified compound film on Ti alloy surface

Abstract

In order to obtain and enhance the excellent performance of films with porous microstructure through the micro-arc oxidation (MAO) process on TC4 alloy (Ti–6Al–4V) surface, the composite technology included in MAO and laser remelting (LSM) process was introduced. Two kinds of specimens were fabricated, one was prepared only by MAO process in silicate electrolyte system; the other was treated by LSM process after MAO. Then, subsequently, MAO and MAO+LSM films were fabricated. Scanning electron microscopy, X-ray diffraction, ultra microhardness tester and electrochemical analyzer were used to analyze the microstructure, phase composition, surface hardness and corrosion resistance of two kinds of films. The results show that the film, after LSM from inside to outside, exhibits dense layer, middle layer and remelting layer; the former MAO loose layer is replaced by remelting layer with compact structure and low porosity, as well as the proportion of rutile phase in MAO+LSM film is improved, the hardness and corrosion resistance is also increased and the combination mode of MAO film and the substrate is still kept. Therefore, for improving the properties of MAO film on the Ti alloy surface, the LSM technology plays a promoting role.