Enhancement in the Wear Resistance of Ti-Al-Si Coatings Fabricated by Hot Dipping

Ti-Al-Si coatings with excellent wear resistance were prepared on the surface of Ti plates by using a combination of hot-dip and thermal diffusion processes. The microstructure, growth kinetics and wear resistance mechanism of the coatings were investigated. The results show the coatings by hot dipping achieved good metallurgical bonding as well as presenting a multilayer phase structure, which was roughly divided into a diffusion layer containing Ti(Al, Si)₃, a hybrid layer consisting of ι₂-Ti₃AlSi₅ phase + Al, and the outermost Al-Si alloy layer. After thermal diffusion, the growth kinetics of the diffusion layer (Ti(Al, Si)₃ phase) conformed to the Arrhenius relationship, and the fitted equation for the thickness of the reactive layer versus the diffusion parameter was: y = 2.7 × 10⁻³ exp(− 65,300/RT)t^1/2. In addition, the hardness of the coating immersed for 15 min reached 740 HV, which was about 2.9 times that of the substrate, and the wear rate was only 50% of that of the substrate. The excellent wear resistance was attributed to the hard Ti(Al, Si)₃ phase as well as the integrity of the coating.