Microstructure and properties of in-situ TiB2 matrix composite coatings prepared by plasma spraying

TiB2-TiC and Ti-B4C composite powders were plasma sprayed onto the 45 steel substrates, respectively, for preparing TiB2 matrix composite coatings. The microstructure and properties of as-prepared coatings were investigated comparatively. The coating prepared by plasma spraying TiB2-TiC composite powder showed the characteristics of stacking of partially melted or unmelted feedstock particles, loose microstructure, high porosity, and poor property. For Ti-B4C system, the main phase TiB2 and TiC0.3N0.7 were formed due to the reaction between Ti and B4C during the plasma spraying process. The as-prepared coating displayed dense microstructure and better quality. The properties of the coating prepared by plasma spraying Ti-B4C composite powder were much better than that of the coating prepared by TiB2-TiC composite powder.