Local mechanical characterisation and modelling of the interfacial behaviour in Hi-Nicalon/BN/alpha-Si3N4 ceramic matrix composites by way of instrumented microindentation tests

Microindentation tests (spherical indentation) have been used to evaluate l ocal mechanical properties of Hi-Nicalon fibre reinforced silicon nitride c eramic matrix composite. This technique gave a satisfactory estimate of in- situ longitudinal Young's modulus of both the matrix and the fibres which c orrelates quite well with 3-points bend tests. By means of the same techniq ue, but with a different indenter (pyramidal), the interfacial behaviour ha s been studied. When varying the maximum applied load, F-max, and consideri ng a constant interfacial shear stress, the presence of Poisson's effect ha s been detected. Based on Coulomb's law of friction, a model has been propo sed to extract frictional stress values adjusted for Poisson's effect. The advantages of this model are the explicit integration of all contributions to the clamping stress at the fibre-matrix interface as well as the use of measured topography properties of Hi-Nicalon fibres. (C) 1998 Elsevier Scie nce Limited All rights reserved.