The replacement of electroplating

Abstract

With the increasing concern over toxic wastes produced by conventional metal finishing operations there is a strong drive in the USA to replace “dirty” electroplating processes (especially chrome and cadmium) with “clean” technologies. While many companies and military agencies continue to think in terms of less polluting electroplates, others are turning away from bath technologies completely, in favor of the modern high performance dry coating methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD) and thermal spraying. Under funding from the US Defense Department's Advanced Research Projects Agency, various dry alternatives to electrolytic hard chrome, namely PVD, plasma nitriding, high velocity oxyfuel (HVOF), laser CVD and laser cladding, have been examined for use both in original equipment manufacture and in rebuilding worn components. In this paper hard chrome replacement is used to illustrate the requirements for replacement of electrolytic coatings in general. Hard chrome alternatives are being evaluated to ensure not only that their performance is at least comparable with the chrome they replace, but also that they fit with the way in which the coated components are produced, used, and refurbished. They must be reliable and cost-effective, and must fit the needs of the end user over the entire life cycle of the coated component. HVOF, PVD and duplex plasma-nitride PVD coatings show great promise as replacements in a variety of applications, from bearing surfaces and hydraulics to decorative finishes. The combination of performance data with cost analyses shows that these alternatives can be cost-effective chrome replacements. For example, HVOF coatings can provide more than twice the life in sliding wear at half the cost.