INTERFACE STUDY OF TIN-COATED AND TI-TIN-COATED STAINLESS-STEEL AISI-304 WITH ASYMMETRIC GLANCING ANGLE X-RAY-DIFFRACTION AND CLASSICAL BRAGG-BRENTANO X-RAY-DIFFRACTION

The effect of an intermediate titanium layer between a physically vapour deposited TiN coating and an AISI 304 austenitic stainless steel substrate is studied by means of classical Bragg-Brentano X-ray powder diffractometry (XRD) and asymmetric glancing angle X-ray diffraction. The latter makes it possible to study very thin layers on polycrystalline materials. Both X-ray diffraction (XRD) techniques reveal the presence of a gamma'-Fe4N phase in the top layer of the substrate when no intermediate titanium layer is deposited on the stainless steel substrate. The results from XRD analysis are correlated with results obtained earlier with scratch tests on identically prepared samples with and without an intermediate titanium layer and coated with a 2-mu-m thick TiN layer. The early failure of the adhesion of the TiN coating when no intermediate titanium layer is deposited can partially be explained in terms of the formation of a gamma'-Fe4N phase in the top layer of the substrate.