Microstructure characterization and mechanical properties of thermal sprayed Ni-20wt. %Al coating

Thermal sprayed Ni-20 wt. %Al coating is fabricated on 6061-T6 aluminum alloy substrates by twin-wire arc spraying（TWAS）. Experimental results present that the average bonding strength is around 53 MPa and the average hardness reaches 325 HV. The Vickers microhardness of NiAl and Ni₃Al intermetallic compounds is larger than that of the substrate,which is beneficial for improving the wear property. Wear mechanism exhibits features of adhesive wear. Friction and wear test results indicate that the wet friction coefficient is higher than the coefficient of dry friction after 200 cycles,and variations of the wet friction coefficient are relatively smaller.