Synthesis of Ni-P-PTFE-nano-Al 2 O 3 composite plating coating on 45 steel by electroless plating

Hybrid Ni-P alloy plating coating containing nano-A1₂O₃ and polytetrafluoroethylene (PTFE) particles on the substrate of 45 steel has been prepared by an electroless plating method. The microstructure, microhardness, and wear resistance of the composite plating coating were analyzed using a microhardness tester, optical microscope, scanning electron microscopy, X-ray diffraction, and friction-wear tester. The results show that the Ni–P–PTFE–nano-Al₂O₃ composite plating coating with high wear resistance and a low friction coefficient, made by the combination of 3g/L nano-A1₂O₃ and 10 mL/L PTFE particles in plating solution, was responsible for enhancing tribological and lubricating properties on the 45 steel surface. The microhardness of the Ni-P-PTFE-nano-Al₂O₃ amorphous coating was HV452; its hardness was correspondingly increased and reached HV756 with a heat treatment at 350°C for 1 h, with the PTFE particles in the coating undestroyed. Simultaneously, the wear loss was 1.6 mg and the friction coefficient was 0.11, the cooperative effect of both particles enabled the Ni-P-PTFE-nano-A1₂O₃ composite coating to have highly wear-resistant and lubricating properties.