Mechanical and metallurgical properties of plasma sprayed and laser remelted Ni-20Cr and Stellite-6 coatings

Ni-20Cr and Stellite-6 powders have been sprayed on boiler tube steels ASTM-SA210-grade A1, ASTM-SA213-T-11 and ASTM-SA213-T-22 through shrouded plasma spray process. NiCrAlY was sprayed as a bond coat of around 150 μm before applying these coatings. The mechanical and metallurgical properties have been measured. Metallography, XRD and SEM/EDAX techniques have been used to analyse the coatings. Considerable reduction in the microhardness and porosity has been observed after laser remelting of the coatings. The laser remelting has further contributed to significant dilution of coating due to inter diffusion of atoms.