Raman mapping of local phases and local stress fields in silicon–silicon carbide composites

Silicon–silicon carbide (Si–SiC) composites have emerged as a new class of materials with superior properties like high resistance against oxidation and corrosion, low thermal expansion coefficient and high mechanical strength. This enabled the composite to be successfully utilized in different industrial applications, such as combustion chambers, gas turbines, heat exchangers, fusion reactors, seal rings, welding nozzles, valve discs and ceramic engine parts. The strength of such composites showed a dependence upon their internal granular structure, since the latter was found to affect local stress distribution in the composite. In this study, we developed a Raman spectroscopy based technique to monitor local composition and local stress fields in Si–SiC composites. The Raman technique was used to monitor local stress fields’ development as the composite is globally loaded in compression for two different composites with reinforcement volume fractions of 13 and 34%. Our results show that the Raman based technique is very suitable for monitoring the local stress fields and their development as the composite is globally loaded. Secondly, it was found that in composites with high volume fraction of reinforcement, local stress fields are more uniform and homogeneous than in composites with low fraction of reinforcement.