Microindentation tests as a tool for the estimate of mechanical propertiesand the modeling of the interfacial behavior of ceramic matrix composites

This article has the scope of presenting the usefulness of microindentation tests for the estimate of in-situ mechanical properties of the matrix and fibers as well as the assessment of interfacial behavior in ceramic matrix composites. For this concern, we have choosen the example of Hi-Nicalon/BN/ silicon nitride ceramic matrix composite. Using the multiple unloading proc edure, which has been described in detail elsewhere [Drissi-Habti M, Nakano K. Comput Sci Technol 1997;57(9-10):1381-1389], the longitudinal Young's m odulus of the fiber and the matrix have been estimated. The values are in g ood agreement with previous results. Using the same technique, the interfac ial properties have been checked. When varying the maximum applied load and considering a constant interfacial shear stress, the presence of Poisson's effect has been identified and a model, based on a Coulomb law of friction , has been proposed to derive frictional stress values adjusted for the con tribution of the expansion of the fibers. From the results presented herein , the main point which should be noted is the wide range of applications pe rmitted by the microindentation technique for the micromechanical character ization of ceramics and ceramic matrix composites. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.