Fiber reinforced ceramic composites for hot gas and fire retardant applications in automotive

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Fiber reinforced ceramic composites for hot gas and fire retardant applications in automotive

Weichand, Patrick / Gadow, R. / Jiménez, M.

Abstract An increasing interest in weight saving and lightweight construction can be seen over the last decade, not only in typical lightweight sectors like aviation, but also in almost all industrial fields. These new trends feature new applications with new requirements for materials in contrast to traditional engineering materials like steel, titanium or aluminum. Fiber reinforced polymers have become commodities. Especially carbonfiber- reinforced-plastics (CFRP) offer excellent specific mechanical properties. The low density in combination with superior strength and modulus feature them as the ideal construction material for lightweight applications. In some areas of application, polymer matrix composites (PMC) reach their technical barriers. The main limiting factor is the slight thermal stability related to the polymeric matrix. Standard matrix materials for these composites are epoxy or polyester. They are usable up to about 120-200 °C. High temperature polymers can increase the usable temperature window up to 350-380 °C. This increase in thermal stability is bought with a decoupling of costs for matrix material and processing. Typical high temperature polymers are cyanate esters, polyimide (PI) or poly-ether-ether-ketone (PEEK). These matrix materials offer decent mechanical properties also in the intermediate temperature range. The main disadvantage is their price level. Actually they are priced between ten times (PEEK) up to 100 times (PI) higher than epoxy matrices. Therefore high temperature polymers are only interesting for special applications in aviation. Common to all polymeric matrices, both standard systems and high temperature polymers, is the flammability. Therefore applications in hot gas and fire retardant environments are scarce. The addition of flame inhibitors can help in certain cases. Typical additives are aluminum- and magnesium-hydroxide, zinc borate, etc.. Most of them emit toxic products while flame retarding.