Development of a novel lateral force-sensing microindentation technique for determination of the interfacial bond strength.

摘要

Research was conducted to develop a novel lateral force-sensing micoindentation method for determination of the interfacial bond strength for coatings/films and composite materials. During such a test, microindentation is performed near an interface with in situ monitoring of changes in lateral force, which is sensitive to interfacial debonding. The critical indentation load that corresponds to interfacial debonding can be measured and used to quantitatively determine the interfacial bond strength, in cooperation with the finite element analysis (FEM) and a quadratic delamination criterion (QDC). In order to understand the role of interfacial stress in inducing interfacial debonding and to evaluate the sensitivity of the lateral force change to interfacial debonding, a finite element study was conducted to investigate interfacial debonding processes and the effects of indentation parameters on the lateral force response to interfacial failure. The effects of indentation parameters, including indenter geometry, indentation location and material properties, on interfacial stress distribution were analyzed in order to provide guidelines for efficient application of this technique to different interfaces. Optimum indentation conditions were identified for three typical interfaces (Al-ceramic, steel-ceramic and tool steel-ceramic), which represented soft-hard, medium-hard and hard-hard interfaces. This method was applied to evaluate the interfacial bond strength of thermal-sprayed Al2O3/TiO2 coatings with regularly grained and nano-grained microstructures. The results were compared to those obtained from a pull-off test. The consistency between the experimental tests further supports this new technique.