Pre‐Treatment of Si₃N₄ Filler Particles for the Improvement of Si₃N_4filler/Si–C–N_matrix Particulate‐Reinforced Composites

Abstract

The surface of Si3N4 filler particles was modified by heat treatments before the onset of the precursor impregnation and pyrolysis process. The strength, Young's modulus, and hardness of Si3N4filler/Si–C–Nmatrix particulate‐reinforced composites (PRC) were improved up to 50%, 60%, and 71%, respectively, by the treatment. Si was formed at the surface of the Si3N4 filler particles by the treatment, which induced a strong bonding between the filler and the Si–C–N matrix during pyrolysis by a carbothermal reaction, thus improving the properties of the PRC.

SiC Particulate‐Reinforced Si–C–N—Highly Oxidation Resistant Composites at 1500°C in Air

“…SiC is thermally stable at 2000°C and SiO 2 formed on SiC was mostly removed before the PIP process by the pretreatment at 1750°C in Ar 7 . Accordingly, the weight loss of the PRC above 1400°C in Ar (5% at 1800°C, Fig.…”

“…2a indicated that the enlargement of pores at the surface of the 1350‐6cycle PRC after the heating at 1500°C in Ar (Figs. 3a and b) was caused by the decomposition of the Si–C–N matrix 7 . The specimen shown in Fig.…”

“…The average pore diameter of the PRC was measured to be 32 nm 7 . Gas phase transport in porous media mainly takes place by the Knudsen diffusion, ordinary diffusion and viscous flow 12 .…”

“…The compacts were heated using a graphite furnace at 1750°C for 2 h in Ar (1.5 atm.) in order to remove SiO 2 and humidity from the surface of SiC 7 …”