Studies of physical vapour deposition interfaces generated by Ti ions in a steered arc discharge

The deposition of ceramic coatings of the type TIC/N on steels enhances the surface properties of the coated substrate. A critical stage in the Are Bond Sputtering(TM) process, using the combined steered are and unbalanced magnetron, is the titanium ion etch which improves the adhesion of the TiN coating to the substrate. Conversion electron Mossbauer spectroscopy (GEMS) has provided evidence that the ion etch pretreatment involves the formation of phases including FeTi at a narrow interface region. To detect these phases it has been necessary to enrich substrates with the Mossbauer isotope Fe-57. The enriched Fe-57 substrates have been treated by a range of ion etch processes and then characterized by GEMS. The role of the FeTi in improving coating-substrate adhesion is not fully understood but work is currently underway using XTEM, SNMS, Auger electron spectroscopy, etc., with GEMS to gain an understanding of the mechanisms involved. (C) 1997 Elsevier Science S.A.