Sliding wear behaviour of thermally sprayed WC–20Cr3C2–7Ni and La2O3 composite coatings

Abstract

In this paper, the sliding wear behaviour of WC–20Cr3C2–7Ni and lanthanum (III) oxide (La2O3) composite coating is investigated. The influence of lanthanum (III) oxide is evaluated by varying its proportion (1, 2 and 3 wt%) in WC–20Cr3C2–7Ni coating material. The high-velocity oxy-fuel (HVOF) technique is used to deposit the coatings on AISI 1020 carbon (C) steel. The mechanical strength and metallurgical quality of the deposit were confirmed by microhardness, adhesive strength and porosity measurements; scanning electron microscopy; and X-ray diffractometry. Further, the sliding wear behaviour of the composite coating is tested on pin-on-disc apparatus with silicon carbide (SiC) as counter material at room temperature. From the investigation, it was found that 2% lanthanum (III) oxide in WC–20Cr3C2–7Ni coating achieved good adhesive strength with minimum wear rate. Addition of lanthanum (III) oxide in WC–20Cr3C2–7Ni prevented the coating from undergoing boundary segregation, crack propagation and grain refinement. Abrasion and ploughing are the common wear mechanisms observed in worn surfaces.