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SiC composites have been developed by various processing methods, i. e. reaction bonding, CVD/CVI and liquid phase impregnation. This class of composites is handicapped by the high cost of investment and processing, interface coatings and raw materials and therefore only attractive for applications in astronautics and military aviation. Polymer Matrix Composites (PMC) are widely used in lightweight applications. The manufacturing technologies are fully developed and raw materials are cheap. The major drawback and limiting factor of these reinforced polymers is the limited service temperatures. Novel composite materials, bridging the gap between PMC and CMC, are manufactured by the use of polysiloxanes as SiOC matrix precursor. Such competitive free formable composites are capable for service temperatures up to 800 °C even in oxidative atmosphere. In order to make the material attractive for series applications, cost effective manufacturing technologies like Resin Transfer Moulding (RTM), filament winding or warm pressing techniques are employed. Beside the improved thermal and chemical resistivity in comparison to reinforced polymers and light metals, a major benefit of SiOC composites is investigated in the field of friction materials. A promising alternative to carbon and synthetic ceramic fibers are mineral based Basalt fibers. These lightweight fibers show high thermochemical stability up to 700 °C, are relatively cheap and became recently available in industrial scale.

Epoxy-based fiber-matrix composites based on a single-component curing system with pot times >>two weeks are described. Bisphenol-A-diglycidyl ether and hexahydrophthalic anhydride were used as epoxy matrix precursors; 1,3-dicyclohexyl-3,4,5,6-tetrahydropyrimidinium carboxylate (6Cy-CO 2 ) was used as latent pre-catalyst. Glass fiber-reinforced epoxy resins were obtained both via thermal curing under air and under vacuum-assisted resin infusion conditions. The high quality of the resulting composites and the absence of any air inclusion were confirmed by DSC and x-ray tomography. Rheological and kinetic data revealed that the 6Cy-CO 2 -based systems allow for an advanced processing and outrival commercial amine-based hardeners in terms of speed of curing.

Promising lightweight composite materials, bridging the gap between Polymer and Ceramic Matrix Composites, are manufactured as polymer derived ceramics by the use of polysiloxanes and basalt fibers. Such competitive free formable Hybrid Composites are supposed to be capable for lightweight applications in a temperature range between 300 °C and 850 °C and short time exposure up to over 1000 °C, even in oxidative atmosphere. Cheap raw materials like basalt fibers and siloxane resins in combination with performing manufacturing technologies can establish completely new markets for intermediate temperature composites. These attributes enable the Hybrid Composites as ideal material for fire retardant applications in automotive engineering and public transportation, as well as in fire protection systems in electrical and civil engineering applications. In this study, the most prominent fields of application and engineering solutions for Hybrid-CMC are reviewed and the results of the thermal resistivity analysis effectuated on basalt fiber reinforced SiOC samples are presented. This study consisted of several air exposures between 1 h and 50 h and temperatures in the range of 650 °C to 1100 °C. Remaining mechanical resistance was characterized by Impulse Excitation Technique (IET) and Interlaminar Shear Strength (ILSS) tests. Basalt fiber reinforced samples exhibited a decent level of mechanical performance even after the most demanding exposures. Due to the poor oxidation resistance of carbon fibers, Cf/SiOC composites were completely degraded after long-term exposure at 500 °C in air.

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