Study of electroless Ni-P-BN-WC composite coatings and their properties

In this research Ni–P matrix embedded with WC and BN particles, were applied on low-carbon steel and produced Ni-P-BN, Ni-B-WC and Ni-P-BN-WC composite Coatings. Scanning electron microscopy (SEM) and optical microscope were used to characterize the structures and surface morphologies of coatings which indicated that particles were uniformly distributed throughout the Ni–P matrix. The micro-structure and phases like Ni3P were investigated and analysed by X-ray diffraction (XRD) which reveal that electroless Ni–P coatings are amorphous. Micro-hardness and wear behavior of the electroless composite coatings were assessed respectively, by a micro-hardness tester and a pin on disc wear test apparatus. The comparison between Ni-P coating and Ni-P composite coatings exhibited that Ni-P-BN-WC coatings had combination of tribological properties of Ni-P-BN and Ni-P-WC coatings; it meant that Ni-P-BN-WC coatings had a good wear resistance, anti-sticking performance and self-lubrication properties at high loads. The corrosion behavior of coatings and effect of co-deposited particles on it, were investigated in 3% NaCl solution, which showed bad effect of BN on corrosion resistance. Micro-hardness, friction factor and corrosion resistance of Ni-P-BN-WC coating were also studied after heat- treatment.