A ceramic particulate composite composed of oxide, and carbide ceramics was found to have high strength, hardness, and fracture toughness values. A composition consisting of Al2O3 with 15 vol% SiC and 15 vol% B4C additions was produced by hot-pressing at 1650⁰C for 30 min, with full density reached after ~5 min at temperature. Both WB and WB2 were observed, with the W source presumably an impurity from WC milling media, and Al18B4O33 was also detected following densification. Strength was~880 MPa, which is greater than values reported for comparable composites of Al2O3 containing 30 vol% SiC or B4C. Vickers hardness was ~21 GPa, and fracture toughness was ~4.5 MPa m1/2, comparable to values reported for the binary mixtures. The calculated critical flaw size of the material was similar to the size of the SiC/B4C clusters and microcracking at grain boundaries. The latter resulting from thermal expansion mismatch between the Al2O3 matrix and SiC/B4C resuborcing phases.
- Aluminum oxide,
- Boron carbide,
- Hot-pressing,
- Microstructure,
- Silicon carbide,
- Strength,
- Binary mixtures,
- Fracture toughness,
- Grain boundaries,
- Hot pressing,
- Thermal expansion,
- Vickers hardness
Available at: http://works.bepress.com/greg-hilmas/11/