High Temperature Oxidation Resistance Of Nimosi Composite Coatings On Ti6al4v Alloy By Laser Cladding

In order to enhance the high-temperature oxidation resistance of Ti6Al4V alloy, Ni-48% Mo-32% Si precursor mixed powders were adopted to prepare the composite coatings by laser cladding. The phase composition, microstructure, high temperature oxidation resistance and wear resistance of the composite coatings were analyzed, and the corresponding mechanisms were discussed. Results show that the composite coatings with no cracks have metallurgical bonding with the substrates. The enhanced phases composed of primary Ti5Si3/MoSi2/Mo5Si3 are well-distributed in the inter-primary alpha-Ti and NiTi intermetallic compounds matrix. Relatively dense oxide films consisting of TiO2/SiO2/NiO are formed on the surface of the composite coating, indicating good high-temperature oxidation resistance after isothermal oxidation test at 800 degrees C for 100 h. While the oxide films of Ti6Al4V alloy are mainly porous TiO2, and the surface is severely oxidized. The weight gain per unit area of the composite coatings and the substrate after oxidation is 1.31 and 23.38 mg/cm(2). While the friction coefficients of the composite coatings and the substrate are 0.44 and 0.52, and their wear rates are 16.2x10(-5) and 22.6x10(-5)mm(3)/Nm. This means that tribological properties of the composite coatings are also obviously improved.