Corrosion Resistance and Wear Resistance of Coating by Different Processes with TC4 Titanium Alloy Coarse Powder Rare Materials

TC4 titanium alloy coating on the substrate surface of AA1060 Al and Q235 steel was prepared by four processes including high velocity oxygen-fuel spraying, atmospheric plasma spraying, laser cladding and laser remelting of high velocity oxy-fuel spraying coating by taking TC4 titanium alloy coarse power as raw materiats, respectively. The phase composition, microstructure, corrosion resistance and wear resistance of the coating under different processes were studied comparatively. The results show that the high velocity oxygen-fuel spraying coating and atmospheric plasma spraying coating were mainly compesed of α phase, and the atmospheric plasma spraying coating also contained some TiO phase. The bonding mode between the two coatings and substrates was mechanical bonding, and the porosity was relatively high. The main phase of the laser cladding coating and laser remelting high velocity oxy-fuel spraying coating on the Al substrate surface was compesed of α phase, while the β phase was on the Q235 steel substrate surface. The bonding mode of the two coatings with substrate was metallurgical bonding, the structure was relatively dense, the grains were relatively fine, and the porosity was extremely low. The average hardness of the atmospheric plasma spraying coating reached 476 HV, which was about twice that of the high velocity oxygen-fuel spraying coating. The average hardness of the laser cladding coating and laser remelting coating exceeded 550, 650 HV, respectively. The hardness of coating on Q235 steel substrate surface was higher than that on Al substrate surface. The average bonding strength of atmospheric plasma spraying coating was about 30 MPa, which was more than 30% higher than that of high velocity oxy-fuel spraying coating. In the 3.5wt% NaCl solution, the four coatings in the order of free corrosion current density from small to large were laser cladding coating, atmospheric plasma spraying coating, laser remelting high velocity oxy-fuel spraying coating and high velocity oxy-fuel spraying coating. On the Al substrate surface, the friction coefficient of laser cladding coating was the smallest, and the wear rate of atmospheric plasma spraying coating was the smallest. On the steel substrate surface, the friction coefficient of laser remelting high velocity oxy-fuel spraying coating was the smallest, and the wear rate of laser remelting high velocity oxy-fuel spraying coating and atmospheric plasma spraying coating was similar, and smaller than those of the other two coatings. The atmospheric plasma spraying technology had the best performance and cost advantages in preparing TC4 coatings with coarse powders.