Microstructure and wear resistance of YPSZ coatings deposited by supersonic plasma spraying

In order to obtain a kind of high temperature-resistant and wear-resistant material for continuous casting molds, yttria partially stabilized zirconia (YPSZ) coatings were prepared on pure copper substrates by high-efficiency supersonic atmosphere plasma spraying (SAPS). The microstructure of the coatings was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), color 3D laser scanning microscopy and image software (Image-pro Plus). The wear resistance of the coatings and the effect of chemical hardening on the wear resistance were investigated through a pin-on-disk tribometer under dry friction at room temperature. It is found that the composition of the coatings is completely t'-ZrO₂ phase. The fracture microstructure is composed of columnar crystals and a small amount of partially melted particles. The cross-sectional morphology exhibits good integrity. The porosity and the surface roughness are 1.2% and 6.457 tim, respectively. Pin-on-disk test against corundum show that the friction coefficient, average wear width and wear volume of the coatings before chemical hardening is 0.5 to 0.6, 3638.8 μm and 1.25508×10^-2 mm³, respectively. The wear mechanism is abrasive wear resulting from brittle fracture. The wear resistance of the coating after chemistry hardening is greatly improved that the width and volume of wear reduce drastically and the degree of brittle fracture is lighter.