Development and Characterization of Hard and Wear Resistant MMC Coating on Ti-6Al-4V Substrate by Laser Cladding

Abstract

AbstractTi-6Al-4V, due to its high specific strength and resistance to corrosion, is one of the highly useful materials in aerospace, automobile and chemical industries. Poor hardness and wear resistance properties restrict its further applications. So surface modification of Ti-6Al-4V is necessary surface to enhance its tribological properties. Multi-phase and multi component coating development is one of the present research trends in surface engineering arena. In the present study it was attempted to develop a multi-component coating by laser cladding process using a pre-placed powder mixture containing Ni5Al (50 vol%) + hBN (10 vol%) + B4C (20 vol%) + SiC (20 vol%) on substrate of Ti-6Al-4V to improve its tribological performance. A nano-structured coating was formed with micro hardness (780 HV0.05). X-ray diffraction (XRD) identified the presence of compounds like TiC, BN, TiB2, SiC, and intermetallics of Ni-Ti in the coating. The wear behaviour of the composite coating was assessed by ball on disc type wear and friction monitor at 10N load at 300 RPM taking a track diameter of 5mm. Specific wear rate and coefficient of friction (μ) were found to vary from 0.6E-12 to 2.2E-12 m3/N-m and from 0.15 to 0.45, respectively, due to rubbing of coated surface against tungsten carbide ball. The microstructure was explored by Scanning Electron Microscopy (SEM)