MECHANICAL-PROPERTIES AND ADHESION STRENGTH OF TIN AND AL COATINGS ONHSS, STEEL, ALUMINUM AND COPPER CHARACTERIZED BY 4 TESTING METHODS

TiN and Al coatings on substrates of high-speed steel, steel, aluminiu m and copper have been used to study mechanical properties of coating systems, especially the adhesion of the coating. The quantities measur ed are internal stress of the coating, determined by X-ray diffraction , the critical load of the scratch test, the microhardness obtained by the indenter technique, and the interface fracture energy, determined by a three-point bend test developed recently by the authors. The fra cture energy, G(c), is a measure for the adhesion strength of a coatin g system, The effect of bias voltage, sputter cleaning and contaminati on of the substrates on the adhesion strength and other mechanical pro perties are investigated with the four methods mentioned. Each of the testing methods reveal only specific aspects of the behaviour of the c oating systems. The data obtained depend on bulk properties of the fil m and the substrate material and on properties of the interface. Varia tion of the bias voltage can change them in quite different ways. In a ddition, the inter-relations between the adhesion strength of the coat ing and the failure behaviour of the three-point bend test samples are discussed.