SiC/SiC fibre reinforced Ceramic Matrix Composites (SiC/SiC-CMC) are high-performance ceramics serving applications up to 1200 °C and well beyond. E.g., SiC/SiC is a material of choice for hypersonic applications or in the hot section of aircraft engines, where high mechanical and thermo-mechanical stresses prevail. However, it is very tedious to develop SiC/SiC-components with suitable mechanical strength and fracture toughness. In particular, the SiC/SiC-CMC development is time consuming, since a multi-step process chain must always be performed to obtain standard samples for the mechanical testing.
The goal of this work was to identify a time and cost-efficient way to reduce the number of steps in the material development while increasing the number of test specimens. High efficiency in the SiC/SiC development was achieved by the use of unidirectional minicomposites with a maximum length up to 200 mm. All rovings were first coated by an interphase (CVI-BN/SiC layer) and then embedded in a SiC rich matrix. The matrix composition was tailored by the adaption of a water-based suspension. In the first step, the dry rovings were impregnated by a slurry cast technique. These minicomposites were pyrolized and infiltrated by the silicon melt, doped with Boron to lower the maximum siliconization temperatures. The microstructure after the siliconization was investigated by light microscopy. A correlation between the fibre coating thickness and the fibre attack by the silicon melt was established. A specific test set-up was developed for the tensile testing of the minicomposites. Moreover, the microstructure could be correlated with the mechanical strength.