Synthesis and Characterisation of Ni-Al2O3 Composite coating by Electrodeposition Method

Abstract:

Nickel- alumina composite is a dispersion strengthened nickel based composite, which is used in wide range of high temperature application where high strength & resistance to oxidation corrosion is required. Large numbers of methods are available for the production of composite materials like plasma spraying, electro-less plating, powder metallurgy, molten metal, electroplating etc. But conventionally electroplating is widely used; as it is cheaper than other processes and also gives good quality deposit.

The aim of project was to strengthen the nickel coating by uniform dispersion of fine particles of alumina. For this the process of electrolytic reduction of Ni in the nickel sulphamate solution was adopted to synthesize the Ni coatings on a non- metallic substrate.  The alumina particles (size range 1-5 microns) with concentrations of 5 g/l were then suspended in the bath to prepare Ni-Al₂O₃ composite coatings. The important parameters like temperature, time, pH, current density, and bath composition were selected by studying their influence on the rate of deposition before the Ni-Al₂O₃ composite coating were prepared.

The coatings were characterized pertaining to microstructure, thickness and hardness. It was observed that the hardness increased up to 400 HV with addition of aluminum particles.