ABSTRACT

Coatings are materials deposited on surfaces to enhance performance, that is, resist wear, erosion, corrosion, lower friction, etc. ˜e coating material may have a very diµerent chemical composition than the base material. Since wear, corrosion, and friction phenomenon are restricted on the surface, deposition of a coating allows the use of less expensive base material while protecting the surface. Generally, ferrous-based material oµers improved wear resistance compared to other engineering alloys. However, under extreme conditions, the wear resistance of ferrous material may need to be improved further through deposition of coatings. Aluminum alloys, titanium alloys, and magnesium alloys generally do not oµer adequate wear resistance and therefore require a coating for wear protection. ˜ere are wide varieties of materials available for deposition and the choice of a material depends on the application, compatibility with the base material, base material properties, and the deposition process. Similarly, there is a variety of coating deposition techniques and the selection of a particular technique depends on the substrate material. ˜e following sections will describe various deposition techniques.