ABSTRACT
Currently surface coatings are deposited in numerous ways and used for a variety of purposes: to provide resistance to wear and corrosion, to reduce friction, to provide special magnetic and optical properties, etc. The coatings possess differ ent properties to fulfill the necessary requirements, but the functional characteris tics and performance depend on the adhesion between the coating and the sub strate. In many cases the adhesion between the coating and the base material is the limiting factor for a wider use of surface coatings in different applications. Practi cal adhesion, which is a function of the fundamental adhesion (interfacial bond strength) and the method-dependent factors, is determined as "the force or the work required to detach the coating from the substrate” [1]. It can be measured with various engineering coating adhesion test methods, the applicability and limitations of which have been reviewed by several authors [1-6]. The scratch test is a very widely and routinely used method for quick and simple monitoring of the practical adhesion of a coating to a substrate. The coatings studied by scratch testing span a wide range of applications from wear resistant coatings on cutting tools to optical coatings on glass. The scratch test has been successfully used in the investigation of the effects of deposition variables, interface layer structures, ageing, etc. [7-10]. It is used by industry for quality control purposes and by re search laboratories for studying the mechanical strength of coatings on machine components. For example, over 200 industrial enterprises and research laborato ries worldwide are currently using a single type among the commercially avail able scratch testers.
