1985 Volume 93 Issue 1080 Pages 409-417
In order to investigate the mechanical properties of Si3N4-SiC composites with various microstructures fabricated by a newly developed technique, compression and bend tests were conducted at temperatures from room temperature to 2000K. The following results have been obtained; (1) the Young's modulus is low in low stress range and increases with stress at room temperature, which shows that the materials have a higher flexibility, (2) the stress dependence of the modulus decreases with increasing temperature, and above about 1370K it is reversed, (3) the fracture stress is correlated roughly with the largest pore diameter observed on the polished surface, (4) the strength in vacuum decreases above about 1300K, while the strength in 1 atm. N2 does not decrease up to about 2000K, and (5) there exists a special grain boundary connecting two grains by continuous lattice distortion. The present results show that the composite material, if the microstructure is well controlled, is very promising as high-temperature material.