Herstellung faserverstärkter, reaktionsgebundener Siliziumcarbidkeramiken unter Verwendung intermetallischer Siliziumlegierungen

An advanced manufacturing technology for reaction bonded, carbon-fiber reinforced SiC-composites is shown using intermetallic silicon alloys as reactant. By infiltration of pure silicon in porous preforms, the carbon fibers are converted to siliconcarbide. A toughening effect is only possible, if the C-fiber strands are preserved during the melt infiltration. A screening in the FeSi-system was performed to control the reactivity of silicon with the free carbon, contained as powder as well as fibers in the preform. The chemical reactivity of FeSi alloys with 10-15 wt% Fe provide both, fiber preservation and optimized microstructural properties. The results of tribological tests show long term stable friction behaviour with asymptotic μ-values corresponding to a contact pattern, where the Si(Fe)SiC matrix is bearing and the friction is controlled by the carbon (C-fiber)/SiC-ceramic ratio in the surface. The low specific weight and the low wear of the CMC material open up the possibilities to use it for car lifetime brake disks.