CORRELATION BETWEEN THE INTERFACE STRUCTURE OF A TIN COATING DEPOSITED ONTO AISI 304 AND THE COATING ADHESION

The interface between austenitic stainless steel AISI 304 and three di fferent types of TiN coating, one with and two without an intermediate Ti layer, deposited using the triode evaporation ion plating techniqu e, were characterized using cross-sectional transmission electron micr oscopy, glancing angle X-ray diffraction and resonant nuclear reaction analysis. A highly faulted interface due to the initial plasma nitrid ing of the substrates is observed for one type of deposition without t he intermediate Ti layer. In this case a phase is formed at the interf ace between AISI 304 and the TiN coating, identified as expanded auste nite. Scratch tests show poor coating adhesion of these samples. In co ntrast, a well adherent TiN coating can be deposited onto austenitic s tainless steel without an intermediate Ti layer when the substrate mat erial is not plasma nitrided and a defect-free interface is formed.