The effect of the addition of Al and Si on the physical and mechanical properties of titanium nitride

Abstract

In this work it will be shown that the addition of Al and Si improve not only the oxidation resistance of TiN, but also its adhesion behaviour. For this, Ti 1− x Si x N and Ti 1− y Al y N coatings with 0 ≤ x ≤ 0.3, 0.38 ≤ y ≤ 0.81 and of thickness ranging from 1.2 to 5.6 μm, were deposited onto polished high-speed steel substrates by dc and rf reactive magnetron sputtering. Samples were oxidised in air at temperatures of between 500 and 900°C. The atomic composition was measured by means of Rutherford Backscattering Spectrometry (RBS) and the texture by X-ray diffraction (XRD). Adhesion behaviour was characterised by scratch test experiments. The results show a great improvement in oxidation resistance for both Ti 1− x Si x N and Ti 1− y Al y N systems when compared with that of TiN. For the Ti 1− y Al y N system, higher oxidation resistance was observed for y = 0.65, which is the value where the best results for critical loads were observed. For the Ti 1− x Si x N system, the best oxidation performance was observed for x = 0.3, but the highest critical loads were obtained for x = 0.15.