Tribological and mechanical properties of nanocrystalline-TiC/a-C nanocomposite thin films

This article reports on interrelationships between x-ray structure, mechanical properties, coefficient of friction μ, and wear coefficient k of ∼3000 m thick nc-TiC/a-C nanocomposite films sputtered using unbalanced magnetron from a composed C/Ti target (Ø=100 mm); here nc and a denotes the nanocrystalline and amorphous phase, respectively. It is shown that (1) μ and k of the nc-TiC/a-C nanocomposite film strongly depend not only on its hardness H but also on its effective Young's modulus E* =E/ (1- ν ²); here ν is the Poisson s ratio, (2) the nc-TiC/a-C nanocomposite films with C/Ti>1.5 and the ratio H ³ / E* ² (characterizing the resistance of film to plastic deformation) ranging from ∼0.2 to ∼0.3 exhibit the lowest values of μ and k, and (3) μ increases with increasing load L of the testing ball. The main result of this investigation is the finding that the achievement of the lowest value E* at a given value of H is of key importance in the formation of films with the lowest values of coefficient of friction μ and wear coefficient k.