Tribological, electrochemical and in vitro biocompatibility properties of SiC reinforced composite coatings

In this work, laser engineered net shaping (LENS™) technique was used to create SiC reinforced titanium matrix composite (TMC) on titanium surface. These composite coatings developed by injecting SiC powder into titanium melt pool, created using a high-power laser. The laser parameters strongly influenced the dissolution of SiC particles leading to formation of TiSi₂, Ti₅Si₃, and TiC phases along with residual SiC in the composite layers. A graded microstructure, with high concentration of secondary phases on top compared to the bottom region was formed. The reinforcing ceramic phases in the TMC coatings enhanced the wear resistance of titanium by about 100 times. The wear resistance of the composite coatings in physiological environment found to increase with increase in the laser power and concentration of SiC particles injected into the melt pool. These composite coatings also showed better corrosion resistance than Ti. In vitro biocompatibility studies performed using osteoblast (MG63) and fibroblast cells (NIH3T3) demonstrated non-toxic nature of these composite coatings. It is envisioned that such coatings may find applications in articulating surfaces of load-bearing implants to enhance their in vivo lifetime with reduced metal ion release.