A novel electroless plating of Ni–P–Al–ZrO2 nanocomposite coatings and their properties

Abstract The wear performance of electroless deposited Ni–P–Al–ZrO 2 nanocomposite coatings on mild steel was studied. Nanosized aluminium–zirconium composites were first prepared by mechanical alloying in a high energy planetary ball mill for different extents of time (5, 10, 20, 30, 40 and 50 h). The 50 h milled Al+ZrO 2 powder was then used as the second phase (4 g/L) for the development of electroless Ni–P–Al–ZrO 2 nanocomposite coatings using alkaline bath. The phases, size, morphology of 50 h milled Al+ZrO 2 nanopowder and Ni–P–Al–ZrO 2 nanocomposite coatings were determined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) respectively. These coatings were heat treated at 400 °C for 1 h in argon atmosphere. Wear resistance of coatings was measured by the ball on disc method at different loads (1 N, 1.5 N, 2 N) and velocities (0.1, 0.2 m/s). Microhardness, wear and friction studies of all heat-treated coatings were investigated and compared with Ni–P coatings. The results show that the Al+ZrO 2 nanopowder milled for 50 h shows unevenly sphericsl shape with particle size ranges from 30 to 40 nm. The microhardness and wear resistance of the nanocomposite coatings are improved as compared to Ni–P coatings. Hardness and wear resistance of the nanocomposite coatings further enhances on heat treatment.