Ni-SiC composite plated under a modulated current

Ni-SiC composite coatings were plated under a modulated current in order to control coating properties including ceramic content, hardness, ductility, internal stresses and hot-oxidation resistance. Composites with SIC gradie nt distribution were deposited from a Watts-type bath by reducing the curre nt density from 8 to 3 A dm(-2). When a pulse regime with a frequency of 0. 05 Hz was used, the composite possessed a combination of enhanced hardness and higher ductility together with lower internal stresses. The best resist ance to hot-corrosion at 800 and 1000 degrees C was obtained for the compos ite deposited in pulse-reverse regime and containing 17 vol% of SIG. (C) 19 99 Elsevier Science S.A. All rights reserved.