The influence of HV-APS process parameters on microstructure and erosion resistance of metalloceramic WC-CrC-Ni coatings

Abstract

This article presents an analysis of the effect of high velocity plasma spraying (HV-APS) parameters of WC-CrC-Ni powder. Plasma spraying processes were carried out using a three-electrode Axial III type torch with central powder injection, in which a supersonic nozzle with a diameter of 5/16 inch was installed. The following were taken as variable parameters: power current per electrode (140, 160, 180A), hydrogen flow rate (10, 20, 30 NLPM) and powder feed rate (15, 20, 25 g/min). The obtained coatings were characterized by thicknesses exceeding 200 μm and their porosity was very low (<1%), similar to those obtained by the HVOF method most commonly used for spraying carbide coatings. The obtained coatings were characterized by hardness in the range of 800–950 HV0.5 - depending on spraying parameters. The solid particle erosion test showed that the WC-CrC-Ni coating - regardless of the spraying parameters - has good erosion resistance. The analysis of the obtained test results indicates that the use of the HV-APS process allows producing carbide coatings with properties similar to those obtained in the HVOF spraying method and significantly better compared to conventional plasma spraying (APS).