Wear Behavior and Microstructure of Thermally Sprayed NiCrBSiFeC and Composite NiCrBSiFeC-WC(Co) Coatings

Abstract

In this work, a study was carried out on the friction and wear behavior of flame thermal sprayed NiCrBSiFeC-WC(Co) composite and NiCrBSiFeC coatings subjected to severe wear conditions. For this purpose, flame remelted samples were tested in reciprocating wear conditions based on a cylinder-on-flat configuration. The wear assessment of the coatings was achieved using scanning electron microscopy (SEM) and 3D optical profilometry. The microstructure and the mechanical properties of the coatings were investigated using SEM, EDS and XRD techniques as along with indentation tests. The tribological behavior of the substrate and the coatings was successfully studied thanks to wear tests conducted on an adapted multi test apparatus. The results show that both NiCrBSiFeC and composite coatings induced a significant increase in the steel substrate hardness and wear resistance due to the formation of precipitates with high hardness well dispersed within an ultra-crystalline structure. Besides, adding WC(Co) to NiCrBSiFeC leads to a composite coating with hardness and wear resistance further improved. In return, it increases the coefficient of friction (COF) and the coatings’ roughness. Furthermore, improvements in the surface hardness, the roughness and the coating-substrate adhesion were attained after the remelting process for both NiCrBSiFeC and NiCrBSiFeC-WC(Co) coatings. Wear tracks investigations indicated that reciprocating dry sliding based on cylinder-on-flat test configuration promote several wear mechanisms that may occur simultaneously.