Tribological performance of Yttrium (III) and Zirconium (IV) ceramics reinforced WC-10Co4Cr cermet powder HVOF thermally sprayed on X2CrNiMo-17-12-2 steel

In this paper, an experimental study has been performed on failure analysis of cermet coatings thermally sprayed on X2CrNiMo-17-12-2 stainless steel using a high-velocity oxy-fuel (HVOF) technique. A comparative study was carried out to investigate the microstructural, mechanical and tribological properties of pure and ceramic-reinforced WC-10Co4Cr cermet coatings. Two different feedstocks i.e. Yttrium-III (Yttria) and Zirconium-IV (Zirconia) were used to develop two different ceramic-reinforced WC-10Co4Cr powders. Tribological properties were tested with the help of laboratory scale pot tester. Coal ashes (i.e., fly ash and bottom ash) were used as the erodents. Different parameters like velocity, time, concentration of particles, and impact angle were varied during the tribological experiments. The microstructural analysis reveals the interlocked lamellae splats, pores and unmelted particles on the as-sprayed surfaces. Yttria reinforced WC-10Co4Cr coating exhibit superior tribo-resistance and mechanical properties. The zirconia reinforced WC-10Co4Cr coating has shown good wear resistance in fly ash slurry which possesses a weak acidic nature (pH = 6.32-6.09 for concentration range of 30-60 wt%). Microhardness of WC-10Co4Cr cermet was also improved with the addition of Yttria. The erosion mechanisms were analyzed by using backscattered X-ray scanning electron microscope (SEM), interactive 3D surface plots, and 2D pseudo-images.