The study of interface microstructure and friction properties of single and multiple pass CuCrZr laser cladding on QT500-7 ductile cast iron

Abstract

In this study, the focus was on the fabrication of single and multi-pass CuCrZr coatings on the surface of QT500-7 ductile iron by laser cladding technique. The evolution of the interfacial microstructure between the coatings and the substrate was systematically analyzed, and the friction and wear properties of the multi-pass Cu alloy coatings were tested. The experimental findings demonstrate that during the single-pass melting process, a petal-like Cu-Fe-C phase is formed between the copper alloy layer and the ductile iron substrate, and a Fe₄Cu₃ phase is generated in the interfacial region. The application of multi-pass laser cladding resulted in the formation of a continuous and uniform coating structure, accompanied by an increase in grain size to 13.64 μm. This process suppressed the formation of the Fe₄Cu₃ phase and enhanced the crystalline quality of the Cu-based phase. Friction and wear experiments demonstrated that the porous copper alloy coatings exhibited low coefficients of friction (0.053–0.303) and minimal wear depths at low loads (10 N, 20 N). However, the coefficient of friction increased to 0.523 at a load of 50 N, indicating that the copper alloy layer is less wear resistant at higher loads.