2005 Volume 54 Issue 11 Pages 532-537
We propose a new hybrid method for evaluating the fracture strength of the hard films deposited on soft substrate metal. The method utilizes acoustic emission (AE), corrosion potential fluctuation (CPF) data and Finite Element Method (FEM) analysis. Both the AE and CPF were simultaneously detected during the Vickers indentation test into the hard film (TiN) in a buffer solution (pH: 4.0 phthalic acid) and used for the determination of both the number and distance of ripple cracks. AE system detected Lamb wave signals from the Mode-I ripple cracks due to the tensile stress induced by the bending of the soft substrate (SUS 304). Event counts of rapid drop (RD-) type CPF with a large shift rate and AE signals agreed well with the number of ripple cracks. Non-linear FEM analysis revealed the Mode-I crack generation in the film at the slight outside of the contact boundary of the indenter and can predict the fracture strength of the film.