Microstructure and mechanical properties of electroless Ni–P–Si 3 N 4 –TiN composite coatings

A high performance electroless Ni–P–Si 3 N 4 –TiN multi-nanocomposite coating was prepared on the surface of AZ31 Mg alloy. The results showed that the surface morphology of this multi-nanocomposite coating exhibits a uniform nodular structure, and the nodular size decreases clearly while increasing TiN nanoparticle concentrations to 2 g/L in the bath, resulting in the finest size of approximately 3 μm. Furthermore, the incorporation of TiN nanoparticles and Si 3 N 4 nanowires into the Ni–P matrix can significantly enhance the microhardness and reduce the friction coefficient of the multi-nanocomposite coatings. The maximum hardness value of 921.4 HV 200 and lowest friction coefficient of 0.54 as well as minimum wear weight loss of 0.7 mg can be also reached at a TiN nanoparticle concentration of 2 g/L.