Studies on Slurry Erosion Behavior of HVOF Applied Y2O3-Added WC–10Co–4Cr Cermet on 13-4 Martensitic Stainless Steel

Abstract

Commercially 86WC–10Co–4Cr hard cermet coating is applied via high-velocity oxygen fuel thermal spray process on hydroturbine blade steel, i.e., 13Cr–4Ni martensitic stainless steel to help improve its wear resistance and life against the eroding action of hard silt particles present in the discharge. The erosive wear resistance of 86WC–10Co–4Cr cermet is improved upon by the addition of 2 wt.% of micro-sized yttrium oxide, which serves as a hard phase. These cermet coatings were deposited on 13Cr–4Ni martensitic stainless steel substrates via high-velocity oxygen fuel method to get an average thickness of 350 µm. Slurry pot wear test (duration 40 h) was used to evaluate the erosive wear resistance of the cermet coatings and the bare 13Cr–4Ni martensitic stainless steel substrate. Silica sand (size range 210–297 µm) was mixed with water to make a slurry of 100 kg/m3 concentration. A sliding speed of 4.45 m/s was maintained between the samples and the slurry. The increase in wear resistance of 86WC–10Co–4Cr cermet due to the addition of 2 wt.% yttrium oxide has been explained on the basis of improvement in hardness from 1048 ± 22 to 1154 ± 25 HV and due to densification effect of yttrium oxide.