Comparison of abrasive wear by rice husk of an HVOF WC–Co–Cr-based coating and an electric arc sprayed coating based on Fe–Cr–B–Si

Abstract

The effect of abrasive wear is particularly relevant in the industrial areas of agriculture, mining, mineral processing and earth moving. Wear problems occur in mills and silos where grain is stored and moved in large quantities through the process of agro-processing. Machines and equipment that work under direct contact with the grain suffer from severe three-body abrasive wear from the rice husks. The main objective of this study was to investigate the abrasive wear behavior of an Fe–29Cr–4B–1.75Si coating sprayed by electric arc and a WC–10Co–4Cr coating applied by the high-velocity oxygen fuel (HVOF) methods. Both coatings used SAE 1016 carbon steel as the substrate. A dry-sand, rubber wheel abrasion test was performed using ASTM G65 standard that employs sand as an abradant. It was compared to a variation on that test that employed rice husk as the abradant. The coatings were characterized by scanning electron microscopy, X-ray diffraction and microhardness. The microhardness values for coatings and substrate were measured using a microhardness Vickers tester equipped with a diamond pyramid indenter. The results showed that the mechanisms of wear differ by the change of abrasive, characterizing a wear by scratches when using the sand, and by microcutting, ledges and cracks when the rice husk is used as an abradant. The WC–10Co–4Cr deposition by HVOF showed satisfactory performance under abrasive wear with rice husk demonstrating a potential for application in agricultural implements working in the rice culture.