Effect of HVOF Gas Velocity and Fuel to Oxygen Ratio on the Wear Properties of Tungsten Carbide Coating

Abstract

The high quality of the thermally sprayed tungsten carbide coatings has been attributed to high particle velocity and relatively low particle temperature. Such thermal spray conditions can be obtained with the HVOF spray process. In comparison to the plasma spray process, in the HVOF spray process the high particle velocity and optimum particle temperature have been associated with very high gas velocity (>1000 m/s) and a relatively low gas temperature (< 2700 °C). In this work tungsten carbide coatings (WC-17Co) were sprayed by the HVOF process with a low and a high gas velocity of 1050 and 1560 m/s, respectively. The spray tests were carried out also with different hydrogen/oxygen ratios. The coatings were abrasion tested in order to find out how gas velocity and the fuel/oxygen ratio affect the coating quality and wear rate. Wear rates of the HVOF sprayed coatings were found to decrease with the higher combustion gas velocity. The coating quality and wear rate became also less sensitive to gas parameters with the increasing gas velocity. The coating microhardness and wear rate were also compared to hot isostatic pressed (HIP) reference material from the same spray powder lot. The HIP sintered test piece was found to be less wear resistant than the corresponding thermally sprayed coatings.

Characterization of Nanostructured and Conventional TiAlN Coatings Deposited on AISI-304 Boiler Steel

“…Microhardness plots indicate some increase in the microhardness of substrate steel at the substrate coating interface. The hardening of the substrates as observed in the current study might have occurred due to the high speed impact of the coating particles during plasma spray deposition similar to the findings of Sidhu et al[05],Hidalgo et al [12],Hidalgo et al [16],Singh et al [17], Hidalgo et al [27] and Hidalgo et al [28].…”

Effect of binders and surface finish on wear resistance of HVOF coatings

“…Tungsten carbide cobalt based is currently the material of choice for producing abrasive wear resistant coatings. 5 However, in some cases, it may also offer insufficient corrosion resistance. In applications that require wear resistance and greater corrosion resistance, the cobalt based material is substituted by nickel, nickel-chromium or cobalt-chromium alloys.…”