Tribological and mechanical properties of carbon nitride films deposited by ionised magnetron sputtering

Tribological and mechanical properties were evaluated for carbon nitride fi lms deposited by an ionised d.c. magnetron sputtering system in which an in ductive plasma was generated between the graphite target and the substrate. Steady-state mean coefficients of friction against hard steel in ball-on-ro tating disc tests were from 0.44 to 0.81 for films deposited with the induc tive plasma, and from 0.36 to 0.60 without the inductive plasma. In each ca se, the friction increased with increasing nitrogen content in the sputteri ng gas and then reached a constant value. The elastic modulus of the films was deduced from nanoindentation experimen ts, and the residual strains in the films were estimated from specimen curv ature measurements. The modulus of the films with no inductive plasma reach ed a maximum with 10 vol.% nitrogen in the sputtering gas, and decreased ma rkedly with the inductive plasma. The modulus also decreased at higher pres sures and higher substrate bias voltages. The strains in the films were alw ays compressive, and increased when nitrogen was present in the sputtering gas. (C) 2000 Elsevier Science S.A. All rights reserved.