A STUDY OF THE COMPOSITION AND PROPERTIES OF EB-ION PLATING TI-B-N COATINGS

Ti-B-N coatings were deposited on W18Cr4V high speed steels by using E B-ion plating with different boron contents. The chemical compositions of the coating are Ti, B and N. It was found that Ti, B and N in the coating are homogeneous, but there exists a diffusion zone at the coat ing/substrate interface on the basis of the results of ion probe micro analysis and Auger electron spectrometry. The boron content of the coa ting is 3-16 at.% given by nuclear reaction analysis. The ratio of nit rogen to titanium of the coating is about 1 given by electron probe mi croanalysis. The microhardness (HV) of the coating is 35-45 GPa (load of 0.25 N). The critical load of the coating using the scratch test is 12-14 N. The sliding friction coefficient of the coating on diamond s tylus is 0.086-0.097 (load of 8.8 N). X-ray diffraction measurement sh ows that the coating consists of f.c.c. TiN, simple orthorhombic TiB, cubic BN and simple hexagonal Ti-B-N phases. As expected, the higher t he boron content, the higher the content of cubic BN and TiB phases; a nd the higher the microhardness, the lower the adhesion.