Novel CMC Material Based on a Si3N4 Matrix

A Process for Cf/SiC Composites Using Liquid Polymer Infiltration

“…In the developed C f /SiC composites the content of carbon fibers decreased to below 30 vol% from above 40 vol% applied for C f /Si 3 N 4 composites to cut down the fabrication cost due to the fact that the price of carbon fibers is lower by a factor of 8 than the cost of SiC powder. 16 The measured porosity of the compact, 27.9%, was very close to the theoretically calculated value, 28.5%. The composition of the green compact calculated from densities of separate components in a given volume of the mold was as follows: carbon fibers, 28.5 vol%; SiC powder, 43.0 vol%; total porosity, 28.5 vol%.…”

“…A much higher value of the flexural strength, 200 MPa, was measured for the C/Si 3 N 4 composites manufactured by this same method. 16 However, the content of C fibers, 44.0 vol%, was much higher in the C/Si 3 N 4 than in the C/SiC composite, and also a mixture of alumina and yttria compounds was added to the matrix as a sintering additive. The sintering temperature was 1350°C and the sintering atmosphere consisted of a mixture of nitrogen and ammonia.…”

“…Such an attempt has been made by a joined team of scientists from ECN and the European Union Joint Research Centre, Petten, Netherlands, and a novel low-cost manufacturing method has been developed, primarily for manufacturing of the C f /Si 3 N 4 and later for the C f /SiC composites. [15][16][17] The C f /Si 3 N 4 composites were first manufactured by a hot pressing technique (too expensive), later by an infiltration process using a threedimensional carbon preform (not homogeneous infiltration), and later by a combined pressure infiltration and polymer infiltration, process. 16,17 In the latter process, a long two-dimensional carbon preform is mounted on a filter within a die cavity (Fig.…”