Influence of Si3N4 Nanoparticles on Microstructure and Properties of Microarc Oxidation Coatings on TC4 Alloy

TC4 titanium alloy was treated by microarc oxidation (MAO) with adding Si3N4 nanoparticles into the base electrolyte. The effect of the Si3N4 content on the surface morphology, corrosion resistance, and wear resistance of the coatings was studied. The results show that MAO coatings with Si3N4 addition present the porous structure, and the coating is the thickest when the Si3N4 content is 1 g/L. The coating with the addition of 1 g/L Si3N4 after acid corrosion test for 7 d shows excellent corrosion resistance with the lowest corrosion rate of about 0.057 mg.cm(-2).d(-1). With the addition of Si3N4, the antibacterial property of MAO coatings is firstly increased and then decreased, which is optimal when the Si3N4 addition is 1 g/L. The Si3N4 addition can obviously enhance the wear resistance of the coatings in the simulated seawater. When the Si3N4 addition is 3 and 4 g/L, the friction coefficient of MAO coatings is low and stable. In addition, MAO coating with the addition of 3 g/L Si3N4 shows the excellent wear resistance.