Microstructure and Room Temperature Wear Properties of a Ni-Cr-B-Si-C Coating Layer Manufactured by the Laser Cladding Process

A Ni-Cr-B-Si-C coating layer was manufactured on a plate of Fe base alloy using a laser cladding process, and the microstructural and mechanical properties of the laser cladded coating layer and a Ni electroplating layer (used as a reference material) were investigated. To identify the microstructural and mechanical properties, scanning electron microscopy (SEM), x-ray diffraction (XRD), room and high temperature hardness, and wear tests were performed. The microstructural observation results confirmed that the layer was mainly composed of γ-Ni phases, Ni4B3, Cr7C3, and Cr5B3. The hardness of the laser cladded coating layer and the Ni electroplating layer were measured to be 950 and 154 HV respectively. Hardness measurements from room temperature up to a high temperature of 700 °C indicated that hardness decreased as temperature increased, but the hardness of the laser cladded coating layer was higher in all temperature conditions. Room temperature wear results showed that the wear loss of the laser cladded coating layer was 1/5 of the wear level of the Ni electroplating layer.