Thin Solid Filrns, 156 (1988) 307 314 PREPARATION AND CHARACTERIZATION 307 S T R U C T U R E OF REACTIVELY SPUTTERED C H R O M I U M CARBON FILMS s. K. SHARMA National Physical Laboratory. New Delhi 110012 (India) J. P. MORLEVAT Department de Metallurgie, Laboratoire d'Etudes du Comportment des Materiaux, Centre d'Etudes Nuclkaires de Grenoble, 38041 Grenoble (France) (Received April 22, 1987; accepted September 3, 1987) Chromium films having a thickness of a few microns have been prepared on stainless steel substrates maintained at different temperatures by reactive sputtering in different partial pressures of methane (CH4) and argon. The composition of these films has been determined by electron microprobe analysis (EPMA). EPMA study of these films revealed that the carbon content in the film increases with increase in the partial pressure of CH 4. Electron diffraction study of the films revealed the normal b.c.c, structure of chromium. However, electron diffraction study of the films prepared at 500 ~'C showed some extra reflections corresponding to d values of 2.33 and 1.77 •. Electron microscopy study of the films revealed crystallites of chromium and the crystallite size of chromium in the film decreases with increase in the partial pressure of C H 4. However, the films prepared at a higher partial pressure of CH4 (2.7 x 10- t Pa) exhibited an amorphous phase together with small crystallites of chromium. The films prepared at 250 °C showed a strained structure when examined by transmission electron microscopy. The film prepared at 500 °C did not show any strained structure. l. INTRODUCTION Thin films of refractory metals are finding industrial applications; in particular, chromium metal is quite important as an alloying element because it provides a protective layer of oxide, preventing further oxidation of material. The structure of chromium films prepared by different techniques has been investigated by various workers and recently it has been reviewed by Gasgnier and Nevot ~. Carbon- and nitrogen-doped chromium layers have also been investigated by Aubert et al. 2 They have observed that carbon-doped chromium films prepared by cathodic sputtering show much higher hardness than pure chromium films. They have also observed that these films showed fretting wear, fatigue and corrosion properties superior to those of electrolytic hard chrome. Recently Lopez and Benseggane 3 have studied the mechanical properties of pure chromium films and chromium films prepared in a CH4 atmosphere similar to those investigatedin the present case. They have observed that the hardness of the chromium films increases by a factor of 3 when 0040-6090/88/$3.50 (C~ Elsevier Sequoia/Printed in The Netherlands