Fabrication and properties of Cfiber/Si3N4 composite by vacuum hot-pressing sintering

Abstract

Cfiber/Si3N4 composites were fabricated by vacuum hot-pressing at 1600°C under an applied pressure of 30MPa with α-Si3N4 powders, sintering additives and short carbon fibers. The microstructure, composition, mechanical and dielectric properties of Cfiber/Si3N4 were investigated. The SEM analysis results reveal that the short carbon fibers were uniformly distributed in the composites. When the short carbon fiber content of the composites increased from 1 to 5wt%, the flexural strength of the composites decreased from 291 to 119MPa and the density of the composites decreased from 3.10 to 2.38gcm−3. The dielectric constant varied from 5 to 135 at P-band. Microwave absorption ability of Cfiber/Si3N4 composites varied greatly over the frequency range 12.4–18GHz and the peak of dielectric constant was bound up with the content of short carbon fiber.