Adhesion of wear resistant hard coatings to steel substrates

Abstract The scratch-adhesion test has been used to monitor the coating-to-substrate adhesion of hard coatings deposited onto steels by two different techniques. In the first instance TiN, TiC and Al 2 O 3 coatings were deposited by chemical vapour deposition (CVD). With the CVD TiC and Al 2 O 3 coatings, pre-critical stylus load flaking could be observed at the edges of the scratch channel. In contrast, TiN did not display such flaking. Energy dispersive X-ray analysis (EDXA) and Auger electron spectroscopy (AES) were used to investigate this behaviour. In the second example, the initial stage of a continuous plasma nitride-TiN magnetron deposition process was varied to optimize the adhesion of the subsequently deposited TiN topcoat. A suite of characterization techniques including hardness determination, AES, profilometry, and optical cross-sectioning was used to help explain the scratch-adhesion test results.