Analysis of the Local Mechanical Behaviour of Ceramics and Composites through Nanoindentation/Scratching and Raman Microspectroscopy

摘要

Nanoindentation/scratch tests were carried out on Si and SiC wafers and C/C-SiC-Si composites. The specimens were submitted to morphological and Raman microspectroscopy analyses to investigate the damage process and the local structural alteration and/or stress redistribution induced by the contact loading. Silicon displays a moderate stiffness and important local plastic deformations. The plastic strain at the indentor print produces compressive residual stresses, partially released by cracking. Silicon carbide is about twice as stiff as silicon. Indentation and scratching also induce local cracking and structural disordering, but to a much lesser extent. Carbon is a soft material and it exhibits a pure elastic behaviour, with no significant damage. The appropriate combination in a composite of such different phases is expected to give rise to high tribological properties.