Wear and corrosion properties of HVOF sprayed WC-Cr3C2 composite coating for application in polysilicon cyclone separator

Abstract

The wear and corrosion properties of the cyclone separator play a crucial role for the preparation of high-purity trichlorosilane in the Siemens method polysilicon cold hydrogenation system. In this work, we used fluent simulation technology to determine the optimal spraying process parameters of high velocity oxy-fuel (HVOF) technology, and the Ni60-WC composite coatings with different content of Cr3C2 were prepared on 316L stainless steel surface by using HVOF technology. The microstructure, phase structure and mechanical properties of the coating were characterized, and the wear resistance and corrosion resistance of the coating were studied. By comparing the friction coefficient, wear rate, wear profile and electrochemical polarization and impedance spectrum of the coating, the effects of Cr3C2 content on the microstructure, hardness, wear resistance and corrosion resistance of HVOF sprayed WC composite coating were studied. The results show that the coating prepared by using the simulation parameters are uniform and compact, the coating is tightly bonded to the substrate. The main phases in the coating are WC, W2C and Cr3C2. With the increase of Cr3C2 hard phase, the wear resistance and corrosion resistance gradually improve. Ni60–35WC–20Cr3C2 and Ni60–35WC–30Cr3C2 volume loss rate is the lowest, the friction depth is the shiniest, compared with the substrate, the wear rate is reduced by more than 95 %. Ni60–35WC–20Cr3C2 has the highest corrosion potential, the smallest corrosion current, the smallest corrosion rate and the largest impedance spectrum radius. However, when the content of Cr3C2 reaches 30 %, the corrosion resistance is the worst. Combined with wear resistance and corrosion resistance analysis, the Ni60–35WC–20Cr3C2 coating is selected to provide support for upgrading and prolongating the service life of the cyclone separator.