Applications of wear-resistant thick films formed by physical vapor deposition processes

Abstract Several physical vapor deposition processes are being developed in Japan to obtain hard refractory carbide and nitride thick films. A good example is the process for producing TiC and/or TiN by (1) reactive evaporation, (2) reactive r.f. ion plating, (3) reactive sputtering, (4) activated reactive evaporation with a probe electrode and a grounded substrate or (5) activated reactive evaporation with a positive-biased or a.c. modulated substrate (low pressure plasma deposition, d.c. or a.c.). Thick films of chromium, chromium carbide and chromium nitride deposited on steel sheets by (6) a hollow cathode discharge process are being investigated for wear applications. This paper describes the examination of such films formed by processes (4)–(6). Wear resistance is correlated to microhardness, X-ray diffraction diagrams, scanning electron microscopy observations and scratch test results. TiC-coated WC-Co throw-away tool tips, for example, prepared in suitable deposition conditions show marked improvements: 1 20 to 1 30 on crater depth and 1 4 to 1 5 on flank wear compared with uncoated tips after 15 min of lathe machining a Ni-Cr-Mo steel SNCM-8 rod at a feed rate of 0.4 mm rev -1 , with a depth of cut of 0.5 mm and at a machining speed of 234-158 m min -1 . The hardness, color and crystal structure are reported for TiN-coated sheets. The features of chromium together with its carbide and nitride films deposited by a hollow cathode discharge process for wear applications are also described.