S. K. Seshadri

Electroless Ni–P composite coatings

This review outlines the development of electroless Ni–P composite coatings. It highlights the method of formation, mechanism of particle incorporation, factors influencing particle incorporation, effect of particle incorporation on the structure, hardness, friction, wear and abrasion resistance, corrosion resistance, high temperature oxidation resistance of electroless Ni–P composite coatings as well as their applications. The improvement in surface properties offered by such composite coatings will have a significant impact on numerous industrial applications and in the future they will secure a more prominent place in the surface engineering of metals and alloys.

Electroless Ni-B-Si3N4 Composite Coating: Deposition and Evaluation of Its Characteristic Properties

Deposition of electroless (EL) Ni-B-Si3N4 composite coating and its characteristic properties are addressed.Hydrogen evolution limits the level of incorporation of Si3N4 particles in the EL Ni-B matrix to 2 wt%. Incorporation Si3N4 particles increased the surface roughness of the matrix but did not influence its structure. The microhardness of EL Ni-B-Si3N4 composite coating in its as-plated condition is 632 ± 17 HV0.1. Heat treatment at 350 and 450°C for 1 h increased its hardness. Adhesive wear is the predominant wear mechanism of EL Ni-B-Si3N4 composite coating. Its corrosion protective ability did not differ much with its plain counterpart.

Wear resistance of electrodeposited Ni–B and Ni–B–Si3N4 composite coatings

The wear resistance of electrodeposited (ED) Ni–B and Ni–B–Si3N4 composite coatings is compared. The effect of incorporation of Si3N4 particles in the ED Ni–B matrix on the surface morphology, structural characteristics and microhardness has been evaluated to correlate the wear resistance. The wear mechanism of ED Ni–B and Ni–B–Si3N4 composite coatings appears to be similar; both involve intensive plastic deformation of the coating due to the ploughing action of the hard counter disc. However, the extent of wear damage is relatively small for ED Ni–B–Si3N4 composite coatings.

Cathodic electrosynthesis of alumina thin films and powders

The present work explores the utility of cathodic electrosynthesis methodology in the preparation of alumina thin films and powders.