Comparison of the adhesion of diamond coatings using indentation tests and micro-Raman spectroscopy

Adhesion of diamond films deposited on Ti interlayer coated copper substrates is compared according to acoustic emission during indentation loading and according to Raman peak shift. The acoustic emission from samples with and without annealing process shows different critical loads, which cause the film delamination and the delamination propagation. A higher annealing temperature and/or a longer annealing time lead to lower critical load or worse adhesion, that is proposed as a result of structure change at the diamond film/substrate interface during annealing. The films exhibiting lower critical load show lower diamond Raman peak shift, which is proportional to residual biaxial stresses in the films. The decrease in the residual stresses is attributed to weakening in the coating adhesion. Therefore, the coating adhesion can be also compared using Raman spectroscopy with the advantage of being nondestructive. (C) 1999 American Institute of Physics. [S0021-8979(99)01022-1].