Development of electroless composite coatings by using <Emphasis Type="Italic">in-situ</Emphasis> co-precipitation followed by co-deposition process

This article presents the studies carried out on the in-situ coprecipitation followed by codeposition of Al₂O₃ and ZrO₂ solids along with Al₃Zr within electroless Ni-P matrix. The present pioneered route for synthesis of composite electroless coating, Ni-P-X (X=ZrO₂-Al₂O₃-Al₃Zr), is developed and studied as a function of concentration of coprecipitation reactants and bath loading factors on coating rate. The coating has been found to grow laterally and vertically to form a continuous layer, and fine second-phase particles, from the coprecipitation reaction, are seen to get entrapped in the Ni-P matrix. The coating rate of the composite coating has been observed to be higher than that of Ni-P alloy coatings for the identical experimental conditions. The morphology, phase analysis, thermal response, and hardness studies of the composite coatings have been reported. This article also includes the characterization of coprecipitated powder obtained. Different analysis methods used in this study include scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDXA) and differential thermal analysis (DTA).