DEPOSITION OF CONTINUOUS AND WELL ADHERING DIAMOND FILMS ON STEEL

The present work reports a successful solution to the problem of diamo nd deposition onto steel. This was achieved through the use of an inte rmediate layer between the substrate and the deposited film. The inter mediate layer consisted of a 10 mu m thick nitridized chromium film. T he chromium film was produced by electrochemical deposition and the ni tridation was performed in an ammonia flow. This nitridation process r esults in the formation of mixed CrN and Cr2N crystalline phases, with the latter in contact with the steel substrate. During diamond deposi tion, partial carbidization of the chromium nitride interlayer took pl ace resulting in the formation of a layer composed mainly of carbides and carbon phases onto which continuous diamond films were deposited. Beneath the carburized region a chromium nitride-rich phase, consistin g predominantly of Cr2N, was observed. The diamond films were deposite d using a hot filament system at a rate of 1 mu m per hour and a subst rate temperature of 800 degrees C. The toughness of the diamond films was evaluated by measuring the minimum load necessary to induce delami nation with a cone-shaped diamond indenter. No delamination events occ urred during indentation up to loads of 1000 N. The samples were exami ned by Auger electron spectroscopy, x-ray diffraction, Raman spectrosc opy, and scanning electron microscopy. It is suggested that chromium n itride interlayers could be employed in the deposition of diamond film s on iron based alloys for industrial purposes. (C) 1995 American Inst itute of Physics.