ADHESION OF WEAR-RESISTANT HARD COATINGS TO STEEL SUBSTRATES

The scratch-adhesion test has been used to monitor the coating-to-subs trate adhesion of hard coatings deposited onto steels by two different techniques. In the first instance TiN, TIC and Al2O3 coatings were de posited by chemical vapour deposition (CVD). With the CVD TIC and Al2O 3 coatings, pre-critical stylus load flaking could be observed at the edges of the scratch channel. In contrast, TiN did not display such fl aking. Energy dispersive X-ray analysis (EDXA) and Auger electron spec troscopy (AES) were used to investigate this behaviour. In the second example, the initial stage of a continuous plasma nitride-TiN magnetro n deposition process was varied to optimize the adhesion of the subseq uently deposited TIN topcoat. A suite of characterization techniques i ncluding hardness determination, AES, profilometry, and optical cross- sectioning was used to help explain the scratch-adhesion test results. (C) 1997 Elsevier Science Ltd.