Showing papers on "Ceramic matrix composite published in 1971"

Silicon nitride ceramic composites with high toughness.

Abstract: THE brittleness of ceramic materials, compared with metals, limits their use in engineering, in spite of such attractive properties as high temperature strength and oxidation resistance. Possible solutions to the brittleness problem therefore continue to be of interest. One approach advocated1 for silicon nitride has been that of fibre reinforcement, practical feasibility of which has been demonstrated2. In the carbon/silica system Crivelli-Visconti3 and Cooper have shown that high work of fracture can be obtained : we present here mechanical property data for silicon nitride/silicon carbide fibre composite materials. The potential of silicon nitride ceramics as engineering materials has been described elsewhere4.

Devices for processing molten metals

Abstract: A nozzle is described for use with molten metals at elevated temperatures. The nozzle consists of a ceramic cylinder surrounded by a resistance heater used to preheat the ceramic part before exposure to the molten metal. Thermal stresses in the ceramic are reduced in two ways. The composition of the ceramic is adjusted so as to minimize thermal expansion and variations in thermal expansion with temperature. Also, high thermal conductivity sleeves are fitted on the ceramic cylinder to reduce temperature variations in the ceramic. These nozzles have considerably longer life than conventional nozzles made from graphite. Other apparatus in common with the nozzle depend for their utility on the ceramic composition; namely, the concentration of magnesia in the stabilized zirconium oxide ceramic.