Nanoindentation and FEM study of the effect of internal stress on micro/nano mechanical property of thin CNx films

Pursuit of ever-increasing storage density has lead to a steady reduction i n head-disk separation which requires protective coating as thin and as har d as possible. It has been found that the internal stress affects micro-tri bological properties of CNx film. In this study, thin hard CNx overcoats wi th different internal stress were synthesized by an ion beam assisted depos ition method. Nanoindentation was used to evaluate the micro/nano mechanica l properties of CNx film. The resultant load-displacement data was analyzed and it was found that the internal stress does affect the elastic modulus and hardness of CNx film according to the magnitude and type of internal st ress. A finite element method was used to simulate the nanoindentation proc ess and to examine the dependence of hardness and modulus on internal stres s. Experimental results were compared with calculated results. (C) 2000 Els evier Science S.A. All rights reserved.