Characterization of Hardness and Stiffness of Ceramic Matrix Composites through Instrumented Indentation Test

The determination of the hardness allows useful qualitative conclusions regarding the mechanical properties of materials. It is one of the most economical characterization methods, since this can be carried out with little effort by small plates. However, the characterization of hardness of ceramic matrix composites (CMCs) is a challenge due to their heterogeneous structure and high level of hardness and has thus rarely been investigated. In this work, the experimental procedure and results of determination of the hardness of CMCs using diamond sphere are presented. Several CMCs with different fibers and with porous and dense matrices were investigated. The instrumented indentation testing method was applied with load transducer and displacement sensor. The visual load-unload curve generated during the indentation process was analyzed to determine the hardness and stiffness of the samples. The test load and the number of load-unload-cycles were varied for selected materials in order to provide recommendations for a suitable experimental procedure, which should be applicable to other CMCs.