Composite Coating on Aluminum-Based Alloys Through Ni-P Electroless Plating Route

The present study deals with the deposition of a layer of Ni-P and Ni-MoS₂-Al₂O₃ composite coating by using different compositions of Al₂O₃ and MoS₂ powders in the electroless (EL) plating bath on Al-alloy substrate. The results are then compared to that of the samples coated without powders in the EL bath. The samples prepared with the addition of powders in the electroless bath show improved surface properties post coating. Various characterizations of the samples are done such as micro-hardness, coating thickness, compositional analysis through EDS and XRD, and surface morphology is seen through FESEM images. The micro-hardness of the powder-coated samples varies in the range of 122.56 HV to 202.42 HV whereas that of the substrate is 110.74 HV at 0.2 kgf loading condition. XRD results indicate the presence of MoS₂, Al₂O₃, Ni, NiAl, SiO₂, and NiO phases that contribute toward the improvement of both hardness and lubricating properties on the Al-substrate post coating.