Corrosion Evaluation of Very Rapid High-Current Vacuum Arc Coatings

The corrosion resistance of Al alloy, Ni, and stainless steel coatings deposited on 1010 steel sample anodes using pulsed high-current vacuum arcs was investigated as a function of the arc parameters. Coating thicknesses of up to 30 ¿m were obtained from a sequence of six 70-ms pulses, indicating effective coating rates of up to 72 ¿m/s. The thicker coatings, and the best corrosion protection, were obtained at higher currents (600-900 A) and short gaps (3 mm). The coatings were generally well bonded to the substrate. The composition of the coatings was approximately that of the source electrode. With optimal arc parameters, all three coating materials gave full corrosion protection during a 5-h salt-spray test, and Al and Ni coatings showed no signs of corrosion after a 48-h test.