Lightweight Engineering with Advanced Composite Materials - Ceramic and Metal Matrix Composites

Abstract

Light weight engineering by materials and by design are central challenges in modern product development for automotive applications. High strength structural ceramics and components were in the focus of R & D in automobile development since the 1970's and CMC have dominated advanced materials engineering in aerospace applications. The limiting factor for their market acceptance was the high processing and manufacturing cost. The automotive industry requires technical performance and high economic competitiveness with tough cost targets. The potential of ceramic matrix composites can be enhanced, if new fast and cost effective manufacturing technologies are applied. This is demonstrated in the case of SiC composites for high-performance disk brake rotors for passenger cars. Light metal composites are promising candidates to realize safety relevant lightweight components because of their high specific strength and strain to failure values, if their stiffness and their thermal and fatigue stability is appropriate for the application, i.e. in power train and wheel suspension of cars. Tailor-made fiber reinforcements in light metal matrices can solve this problem, but the integration of fibers with conventional manufacturing techniques like squeeze casting or diffusion bonding leads to restrictions in the component's geometry and results in elevated process cost mainly caused by long cyc1e times and the need of special tools and additional fiber coatings. A new manufacturing method for metal matrix composites (MMC) made by fast thixoforging is introduced. Thereby, prepregs consisting of laminated fiber woven fabrics and metal sheets or, alternatively, thermally sprayed metal coatings on ceramic fiber fabrics are used as preforms for an advanced thixoforging process for the manufacturing of Al-Si MMC components in mechanical engineering.