Laser Cladding Mo-based Coatings on Copper Alloys to Improve the Current-Carrying Tribological Properties of Cu/Al Friction Pairs

To enhance the current -carrying tribological properties of the Cu/Al friction pair, Ni-based transition -coatings and Mo-based function -coatings were sequentially prepared on copper alloys by laser cladding. The microstructure, mechanical properties, electric conductivity, and current -carrying tribological properties of the coatings were comprehensively investigated. The function -coating consisted of a Mo-rich layer and a high -dilution layer, with a close metallurgical bond formed between the layers. Compared with the substrate, the average microhardness (640.2 HV 0.2 ) and elastic modulus (320.9 GPa) of the Mo-rich layer were increased by 326.8 % and 89.7 %, respectively. The substrate after cladding with the Mo-based coating demonstrated an acceptable conductivity as 78.30 %IACS. The transition -coating infiltrated moderately into the function -coating, promptly filling cladding defects, enhancing grain boundary toughness, and effectively mitigating the significant mechanical property differences between the Mo-rich layer and the substrate. Current -carrying friction tests with the Al friction pair indicated that, under low currents (10 A), the Cu substrate was prone to both adhesive wear and abrasive wear, while the function -coating only exhibited slight abrasive wear. Under high currents (40 A), the Cu substrate experienced severe mechanical wear and electrical wear. Nevertheless, the function -coating still suffered slight abrasive wear with a wear volume of only 1/33 of the substrate owing to the protection and lubrication of the Al adhesion film and the good contact state.