The VDI 3198 indentation test evaluation of a reliable qualitative control for layered compounds
Mono- or multi-layered coated compounds are powerful alternatives of conventional bulk materials, which normally illustrate a restricted surface performance. Nowadays, advanced and complicated techniques are induced in film production devices, leading in this way to the development of an extended variety of different coating types. Herewith, soft, hard or super-hard films can be produced in single or multi-layer textures, serving in this way demanding applications, which require advanced surface attitude. Taking into account the growing industrial and manufacturing demands, a well-organized contest of characterization processes for such coatings is required. This paper describes the methodology and typical results of a fast, reliable and cost effective quality test, which is based on the Rockwell C indentation on planar surfaces of coated compounds. This destructive test, may rigorously exhibit two distinctive properties of the coated compound, i.e. the interfacial adhesion as well as the film brittleness and cohesion. The stress–strain field, which occurs during the indentation and the relaxation stages respectively, must be thoroughly considered in order to obtain secure conclusions, regarding the quality of the coating substrate system.