Enhancing the properties of WC/Co detonation coatings using two-component fuels

Abstract

Detonation spraying of WC/Co was conducted with two-component fuel using a computer-controlled detonation spraying system. The in-flight temperatures and velocities of the particles were calculated and optimized for C2H2/C3H8/O2 and C2H2/C4H10/O2 detonation gas mixtures. The stable spraying mode was realized in a short gun barrel thanks to the formation of a stratified explosive charge by means of precise computer-controlled supply of the gas components. The stand-off distance was varied from 50 to 400 mm and the substrate tilt angle relative to a plane normal to the spraying direction was varied from 0 to 60°. The formation of splats was analyzed to determine the optimal spraying mode. The microstructure and porosity of the coating were studied, and microhardness, bonding strength and wear resistance were measured. It was found that spraying with two-component fuels produces coatings with enhanced properties. For the WC-12wt.%Co coatings, the following characteristics were achieved: porosity of <0.5%, microhardness of 1500 HV300 and ASTM G65 abrasion wear of <1mm3/1000 rev. It was found that the coating properties do not deteriorate significantly with increasing the substrate tilt angle up to 30°: e.g., the abrasion wear increases by 17% only.