Hot Isostatic Pressing of Sintered Si3N4 Ceramics

Abstract

Pressureless sintered Si3N4 ceramics have been hot isostatically pressed (HIP'ed) in a nitrogen atmosphere. An increase in density was observed for all HIP'ed ceramics, although theoretical density was not achieved. The effects of HIP'ing upon bulk microstructure and pore morphology are discussed. Structural modification of the surface and subsurface microstructure occurred during HIP'ing; following reaction between the ceramic and pressurizing gas (N2) Room temperature strength remained essentially unaltered after HIP'ing; however, Weibull modulus was increased. Additionally, HIP'ing had minimal effect upon the bulk oxidation behavior of the ceramics examined.