Numerical simulation of micro-scratch tests for coating/substrate composites

In this paper the micro-scratch test is simulated by ANSYS finite element c ode for thin hard coating on substrate composite material system. Coulomb f riction between indenter and material surface is considered. The material e lastic-plastic properties are taken into account. Contact elements are used to simulate the frictional contact between indenter and material surfaces, as well as the frictional contact after the detachment of coating/substrat e interfaces has taken place. In the case of coating/substrate interfaces b eing perfectly bonded, the distributions of interfacial normal stress and s hear stress are obtained for the material system subjected to normal and ta ngential loading. In the case of considering the detachment of interfaces, the length of interfacial detachment and the redistribution of stresses bec ause of interfacial detachments are obtained. The influences of different f rictional coefficients and different indenter moving distances on the distr ibutions of stresses and displacements are studied. In the simulation, the interfacial adhesion shear strength is considered as a main adhesion parame ter of coating/substrate interfaces. The critical normal loading from scrat ch tests are directly related to interfacial adhesion shear strengths. Usin g the critical normal loading known from experiments, the interfacial adhes ion shear strength is obtained from the calculation. When the interfacial a dhesion shear strength is known, the critical normal loading is obtained fo r different coating thicknesses. The numerical results are compared with th e experimental values for composite materials of thin TiN coating on stainl ess steel substrate.