Reciprocating sliding wear behavior of the heat-treated WC-12Co coatings

Abstract

WC-Co coatings were produced on SS 410 plates and subjected to heat treatment at different temperatures (from 300 to 900 °C). The microstructural studies and structural analysis of the coatings before and after heat treatment were carried out by electron microscopy and X-ray diffraction analysis. From the Vickers indentation method, hardness values were measured, and higher microhardness was observed for the coatings after heat treatment. The sample that was heat-treated at 750 °C exhibited the highest hardness. From the sliding wear test results, the wear resistance of the coatings was observed as increased after the heat treatment. However, it was found that the heat-treated coatings at 600 °C exhibited higher wear resistance. Cracking and fracture were the dominant wear mechanisms observed for the heat-treated coatings, along with coating delamination and oxidation.

Wear and corrosion behaviour of the cryogenically treated tungsten carbide coatings

“…After heat treatment, the hardness was increased to 1501 ± 41 HV0.3. The formation of the secondary carbides is responsible to enhance the microhardness of the as-deposited coatings after the heat treatment [4,5]. Whereas duplex-treated coatings do not show any significant impact on the microhardness of the coatings due to the stabilization of the phases after heat treatment.…”

“…A scanning electron microscope (SEM) (JEOL JSM-6380A, Japan) attached with an energy dispersive spectrometer (EDS) was used to obtain the microstructures, and ImageJ software was used to analyse the microstructure. The heat treatment of the as-deposited coatings was carried out at 750°C for 1 h in an argon environment [5]. The deep cryogenic treatment (CT) was performed on the as-deposited (AD) as well as on the heat-treated (HT) coatings by varying the soaking duration for 1, 2, 8 and 24 h in liquid nitrogen.…”

“…Carbide coatings can be deposited through the plasma spray process but as it possesses higher flame temperature and low particle velocity, the chances of loss of carbon are more, which results in the formation of undesirable new phases and the presence of porosity is also on the higher side [3]. However, the recent thermal spraying processes such as high-velocity oxygen fuel (HVOF) and air fuel (HVAF) have successfully overcome the limitations of the plasma spray process by minimizing the porosity and the decarburization of the coatings as they work at lower flame temperatures and higher particle velocity [3][4][5]. In the automotive and aerospace industries, WC-Co coatings have been extensively employed to develop wear-resisting surfaces as a substitute for chromium-based hard coatings [6][7][8].…”

“…Gallego et al reported that heat-treatment of WC-based coatings at a lower temperature 350°C, provides better wear resistance than at a higher heat treatment temperature due to the microstructural defects related to the oxidation during heat treatment [16]. So, heat treatment should be performed in an inert environment or vacuum to reduce the chances of oxidation that leads to deterioration of the wear resistance of the coatings [2,5,13,16].…”