Electrolytic Preparation of Ni-B4C Composite Coating and its Characterization

Abstract

Ni-B4C composite coatings with various contents of B4C particles were electrodeposited from a nickel acetate containing suspended B4C (<10 µm) particles using N-methylformamide as solvent. Plating variables including current density, B4C concentration in the bath, temperature, and stirring rate were optimized for the highest amount of the B4C codeposition. The deposit’s microstructure and composition were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray analysis. In order to check the suitability of solvent for obtaining satisfactory deposits free from hydrogen (i.e., inevitable in aqueous media due to hydrogen-evolution reaction), the hydrogen content of the composite was also determined. Effects of B4C incorporation and annealing of the composite on microhardness have also been investigated. Composite coatings of superior hardness with minimum strain and hydrogen content were obtained. © 2015, ASM International.