Papers by Author: Zmago Stadler

Abstract: A design study for ceramic pistons was undertaken in order to address the overheating problems associated with the caliper during aggressive braking using modern C/C-SiC brake discs. The reasoning behind the piston design and the choice of the shaping technology are explained. Zirconia-toughened mullite (ZTM) ceramic was chosen for the pistons, because this material exhibits a low thermal conductivity, sufficiently high mechanical strength and fracture toughness, as well as very good thermal-shock resistance. The manufacturing technology of experimental ceramic brake pistons involved compounding of the selected starting powders to form a high-solids-loadingcontaining feedstock, tooling, shaping of green parts by low-pressure injection molding, extraction of the organic binder, pressure-less sintering in air and final machining. Prototypes brake pistons were fabricated and successfully tested as components of motorcycle brake systems in a test laboratory and on a motorcycle racing track.

Abstract: The goal of our research is to develop a carbon-carbon-silicon carbide composite that will unite high fracture toughness of carbon-carbon composite with good oxidation and abrasion resistance and good thermal conductivity of silicon carbide. That can be achieved by the preparation of functionally graded C/C-SiC composites. For the production of C/C-SiC composites with a gradient structure of the ceramic matrix – from a carbon matrix in the core to a SiC matrix on the surface new materials based on C/C composite with SiC nano-particles dispersed in the matrix were produced. Since for the thermo-mechanical properties of such materials, the interface between the carbon fibres and the matrix phase is crucial, we studied the influence of SiC precipitation from the matrix phase on the interface structure and the mechanical properties of C/C-SiC composites. The results show that SiC nano-particels are precipitating around the carbon fibres influencing the interface structure and consequently also the mechanical properties.