抄録
In order to examine the effect of nitrogen ion implantation prior to ceramic coating, the SUS304 substrates were implanted with nitrogen ions, and titanium carbide films were deposited on the implanted substrates by a reactive sputtering method. Hardness measurements and indentation fracture tests were made to evaluate the adhesion properties of these TiC/SUS304 specimens by using a microhardness tester. Friction coefficient measurements and scratch-tests were also carried out.
It was shown that at loads above 0.049 N (5 gf) the hardness of the TiC films deposited on the substrates increased monotonically with nitrogen dose, but for a small load below 0.0198 N (2 gf) the hardness tended to decrease significantly with an increase of nitrogen dose. At relatively high loads above 0.098 N (10 gf) irregular cracks and exfoliation of TiC films were induced on the unimplanted substrates. Such cracking or exfoliation of TiC films was hardly observed on the nitrogen implanted substrates. A significant hardness decrease of TiC films on the implanted substrate was attributed to the effect of the film replication of a plastic deformation of underlying soft material under the conditions of a sufficiently strong adhesion between the film and underlying substrate. The improved adhesion of TiC films to the substrates was considered to arise from the facts: (i) the formation of the complex transition layers at the interface region, denoted by TiC-Ti(C, N)-Ti(C, N, O). (ii) the transformation of Fe and Cr surface oxides into Fe, Cr nitrides and titanium oxides, and (iii) the removal of OH− radicals from the substrate surface by nitrogen ion irradiation.
