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Potential of SiC multilayer ceramics for high temperature applications in oxidising environment

Multilayered ceramics seem very promising for applications at very high temperatures in an oxidising environment. Actually, they present lower cost and better oxidation resistance than many conventional ceramic composites. The multilayered SiC oxidation and shock resistance has been investigated on tubular specimens processed by tape casting and pressureless sintering. Microstructure, oxidation and mechanical behaviour were investigated by micro-XRD, SEM, TGA–DTA-MS, indentation and radial compressive tests. The mechanical characterization showed that weak interfacial bonds are present between the layers. Together with the residual stresses left after the preparation phase, they caused crack deflection and improved toughness with respect to traditional ceramics. These mechanisms persisted even after long-term oxidation at 1600 °C or repeated thermal shock tests. The strength was found to depend on the thickness of the single SiC layer, however it was only slightly affected by thermal treatments.
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