Wear and corrosion mechanisms of Ni–WC coatings modified with different Y <sub>2</sub> O <sub>3</sub> by laser cladding on AISI 4145H steel
Qizheng Cao, Li Fan, Haiyan Chen, Yue Hou, Lihua Dong, Zhiwei Ni
Abstract
Abstract In order to evaluate the effect of rare earth Y 2 O 3 on the wear and corrosion properties of WC–Ni composite coatings, X-ray diffraction, scanning electron microscopy(SEM), electrochemical polarization curve, electrochemical impedance spectroscopy (EIS), and friction and wear tests were used to analyze the metallographic structure, corrosion characteristics in simulated seawater and friction and wear principle of the composite coatings. Results of SEM revealed that the microstructure of the Y 2 O 3 added coatings was refined with the grains changing smaller and the impurity disappearing. The EIS results proved that the addition of Y 2 O 3 brought a positive influence on the corrosion resistance by reducing the capacitance and increasing the R f and R c . The hardness of the coatings with Y 2 O 3 addition tends to be smooth without wild fluctuation, and the coating with 0.5 wt% Y 2 O 3 owned the hardness values reaching 850 HV. With the addition of rare earth elements, the coefficient of fiction values decreased, reaching the lowest (0.3418) at the content of Y 2 O 3 of 0.5 wt%. The surface of the coating without Y 2 O 3 appears grooved due to the abrasive wear; the coatings with Y 2 O 3 did not suffer serious wear and tear. The coating with 0.5 wt% Y 2 O 3 exhibited the best corrosion resistance and wear resistance properties in all the specimens.