Composite number

Materials science

Ceramic

Thermal conductivity

Pressing

Monocrystalline whisker

Mullite

Composite material

Ceramic matrix composite

Flexural strength

Hot pressing

Whisker

Composites

Dense, toughened SiC-whisker-reinforced ceramic matrix (i.e. Al2O3 and mullite) composites were fabricated by hot-pressing powder-whisker mixtures. The densification behavior of the composites was influenced by the temperature, pressing pressure, and whisker content but even at 60 vol pct whisker loading, full density was achieved at 1850 C for the alumina matrix. The mechanical performance of these composites was improved. In particular, the critical stress intensity factor (equal to about 9 MPa sq rt of m in Al2O3 and equal to about 5 MPa sq rt of m in mullite) exhibited substantial improvements (approximately two-fold increases) over monolithic ceramics. In the case of the alumina-20 vol pct SiC whisker composite, the flexural strength was 805 MPa at room temperature and 520 MPa at 1200 C the thermal conductivity was 32 W/mK at room temperature and 10 W/mK at 1000 C. 19 references.

Development of SiC-whisker-reinforced ceramics