Effect of WC-17Co Powder Density on Coating Mechanical Properties and Residual Stress

Abstract:

Three kinds of WC-17Co powders with different densities were selected as starting material, and a coating with 0.3 mm in thickness was prepared by high velocity oxygen fuel (HVOF) method. The porosity of the three coatings was analyzed by SEM, the Knoop hardness and Young's modulus of the coatings were measured by indentation method. At the same time, the residual stress of the WC-17Co coating prepared by powders with different densities was measured by layer-stripping method. Results show that the porosity level of the coatings increases with increasing WC-17Co powder density, while the Knoop hardness and Young's modulus of the coatings decrease with the increase of powder density. The residual stress existing in the WC-17Co coating appears as compressive stress, which increases with the increase of the coating depth, and then decreases rapidly near the coating-substrate interface. The maximum residual stresses of the coatings deposited with powder density of 11.52, 12.86 and 13.49 g·cm^-3 are -798, -986 and -1120 MPa, respectively.

Key words:HVOF;WC-17Co;powder density;mechanical properties;residual stress