The effect of WC content on the bonding strength and mechanical properties of WC/Ni60 coatings of brake disc

Abstract

Laser cladding metal-based ceramic composite coating has significant advantages in improving the surface properties of brake discs. WC powder (5–35%) was mixed into Ni60 powder to prepare different WC/Ni60 composite coatings by laser cladding. The samples were treated by grinding and polishing for further experiments. The effects of WC content on bonding strength, residual stress, fracture toughness, and material strength of cladding coating were studied. At the same time, the fracture morphologies were observed and analyzed by SEM. It was found that the bonding strength of different coatings exceeded 170 MPa. The optimal range of bonding strength was 15–30% WC content. With the increase of WC content, the porosity of the coating increased continuously. When the WC content was 30%, the maximum porosity of the coating was 5.6%. When the content of WC reached 30%, the residual stress of the coating was the largest, but when it exceeded 30%, the residual stress began to decrease. With the increase of WC content, the compression resistance of the coating gradually decreased. The compression resistance maintained a high level, which conformed to the optimal range of bonding strength. When the WC content was less than 35%, the bending strength of the material was improved, which the 25% WC content had the maximum bending strength. The optimal range of bonding strength covered the bending strength. Therefore, when the WC content was 20–30%, which had shown good bonding strength and mechanical properties. In the fracture morphologies, the 20% WC coating was the most smooth, and the bonding strength is the best, which has consistency.