Interface characterizations of diamond-coated tools by scratch testing and simulations

In this study, micro-scratch tests were conducted on diamond-coated tungsten-carbide substrates to investigate coating adhesion. During the scratch testing, high intensity acoustic emission (AE) signals can be clearly detected when the coating delamination occurs. It is also found that the tangential force increase gradually with the normal force, but fluctuates significantly when the critical load of coating delamination is reached. A three-dimensional (3D) finite element (FE) model with a cohesive-zone interface was developed to simulate the scratch process, and by comparing with the delamination critical load from the experiment, the interface characteristic length, the maximum strength and the fracture energy can be obtained. The preliminary results indicate that it is feasible to use the FE simulation combined with scratch tests to evaluate the coating interface behaviors.