In-situ TiC-TiB2 coating on Ti-6Al-4V alloy by tungsten inert gas (TIG) cladding method: Part-II. Mechanical performance

TiC-TiB2 composite coating was produced on Ti-6Al-4V alloy by TIG cladding method (an economical alternative of laser cladding process) through in-situ reactions between Ti and B4C pre-deposited powder mixture. The experimental results revealed significant variation in the hardness value along the depth of the coatings for the alteration of processing conditions, which mainly occurred due to discrepancy in the dilution of substrate material and consequent change in the percentage of hard TiC and TiB2 phases. The fracture toughness of the coatings measured by indentation method are found (5.65-6.97 MPa·m1/2), much higher than that of individual TiB2 or TiC. The sliding abrasive wear test performed against alumina abrasive wheel revealed that abrasion wear is predominant for removal of the coating. However, adhesive wear due to plastic deformation and brittle fracture resulted from the stress induced due to cyclic loading by the abrasive particles are also effective to remove the coating material subjected to the concentration of hard TiC and TiB2 phase in the coating. The produced coating exhibited up to four times higher hardness and three times higher wear resistance as compared to Ti-6Al-4V alloy substrate, which makes the coating a suitable candidate for application in wear resistance components.