Effect of nitrogen on tribological properties of amorphous carbon films alloyed with titanium

The article reports on the dependency of friction and wear of a-(Ti,C,N) films on the nitrogen content. The amount of nitrogen N in the film was controlled by partial pressure of nitrogen pN2 in the Ar + N2 sputtering gas mixture. It is shown that the incorporation of N in the film results in the increase of (i) the coefficient of friction μ (increases from 0.12 to 0.37), (ii) the coefficient of wear k (increases from 0.16 × 10−6 to 0.93 × 10−6 mm3/N m) and the decrease of (i) the film hardness H, (ii) effective Young's modulus E⁎, (iii) the elastic recovery We of film and (iv) the ratio H/E⁎. The changes of μ and k of the a-(Ti,C,N) film correlate well with changes of the film mechanical properties (H and E⁎) and its mechanical behavior (We, H/E⁎ and the ratio H3/E⁎2) characterizing the film resistance to plastic deformation.