ABSTRACT
A coating is a layer of material that is applied over the surface of a substrate, for purposes that may be protective, decorative, or functional.1 Unique functions may be introduced through such surface modication, such as electrical insulation and moisture protection in electronic applications,2 corrosion resistance in biomedical applications,3 thermal barrier for aerospace applications,4 and a variety of other functions.5−7 The performance and reliability of such coatings depend on the mechanical integrity of the coating/substrate systems, that is, adhesion of the coating to substrate. Poor adhesion results in delamination or spallation of coatings that will expose the underlying substrate to severe environmental conditions, such as corrosive gases and liquids, abrasive particles and elevated temperatures, resulting in premature failure.8−10 Proper evaluation of the coating adhesion is important in assessing its tness for service and detecting need for corrective measures.11
