Microstructure and Wear Resistance of TiB2-TiC-Co Coatings by Atmospheric Plasma Spraying

TiB2-TiC-Co composite cermet powders were synthesized through Co-Ti-B4C system by self- propagating high-temperature synthesis (SHS), and TiB2-TiC-Co cermet coatings were produced on Q235 steel substrate by atmospheric plasma spraying (APS). Phase composition and microstructure of the SHS products and APS coatings were investigated, and the tensile bonding strength and wear resistance of the coatings were examined. The results show that the diffraction peaks of Co-Ti-B4C SHS products mainly consist of strong TiB2 and TiC diffraction peaks in addition to the diffraction peaks of a small amount of remained NaCl additive. Both TiB2 and TiC ceramic particles are fine. With increasing the Co content, the disk-like splats are increased on the surface of TiB2-TiC-Co coating, and the surface becomes smooth gradually. The thickness of the coatings is uniform, and the densification is improved. The tensile bonding strength and sliding wear resistance present the trend of firstly increasing and then decreasing. The tensile bonding strength and sliding wear resistance of the coating reach optimum values with 10wt% Co addition. The wear mechanism of the coating is mainly adhesive wear and lamellar peeling wear.