MAGNETRON-SPUTTERED SUPERHARD COATINGS WITHIN THE SYSTEM TI-B-C-N

This paper presents the development of superhard coatings in the Ti-B-C-N system. Coatings are deposited by the magnetron sputtering ionic plating process, using a TiB2 target in the dc mode. Differing compositions of the multi-component hard coatings are achieved by varying the amounts of methane (CH4) and nitrogen (N2) in the reactive atmosphere. Depending on the partial pressures in the reactive atmosphere, all coatings either occurred in X-ray amorphous form or crystallized in a hexagonal structure. The lattice parameters were strongly influenced by the numbers of interstitial C and N atoms. AES and EPMA examinations confirmed the coating composition detected by X-ray microstructural analysis. Techniques used to characterize mechanical coating properties included the Palmquist and Hertzian stress methods, microhardness measurements and the CSEM scratch test Scanning electron microscopy (SEM) revealed an extremely dense coating structure. The most significant property of the coating was the superhardness of the deposited layers, with values of up to 7000 HV 0.05. Coating densities of between 6 and 25-mu-m were realized. Owing to these special properties, the coatings in the Ti-B-C-N system displayed superior wear resistance characteristics in the abrasion test.