DEPOSITION OF CONTINUOUS AND WELL ADHERING DIAMOND FILMS ON STEEL

The present work reports a successful solution to the problem of diamond deposition onto steel. This was achieved through the use of an intermediate layer between the substrate and the deposited film. The intermediate layer consisted of a 10 mu m thick nitridized chromium film. The chromium film was produced by electrochemical deposition and the nitridation was performed in an ammonia flow. This nitridation process results in the formation of mixed CrN and Cr2N crystalline phases, with the latter in contact with the steel substrate. During diamond deposition, partial carbidization of the chromium nitride interlayer took place 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, consisting predominantly of Cr2N, was observed. The diamond films were deposited using a hot filament system at a rate of 1 mu m per hour and a substrate temperature of 800 degrees C. The toughness of the diamond films was evaluated by measuring the minimum load necessary to induce delamination with a cone-shaped diamond indenter. No delamination events occurred during indentation up to loads of 1000 N. The samples were examined by Auger electron spectroscopy, x-ray diffraction, Raman spectroscopy, and scanning electron microscopy. It is suggested that chromium nitride interlayers could be employed in the deposition of diamond films on iron based alloys for industrial purposes. (C) 1995 American Institute of Physics.