Microstructural development of Si3N4–SiC–Y2O3 ceramics derived from polymeric precursors

Abstract

[Si–Y–O–C–N] amorphous powders were synthesized by the pyrolysis at 1000 °C in N2 of chemically modified perhydropolysilazane using n-decyl alcohol and yttrium tri-methoxide. [Si–Y–O–C–N] amorphous powders yielded a unique fibrous microstructure by heat treatment in N2 at 1800 °C. The fibrous microstructure was composed of β–Si3N4 whiskers of submicron in diameter and more than 10 μm in length. Fully dense Si3N4 –SiC–Y2O3 ceramics were also fabricated by heat treatment at 1800 °C followed by powder-vehicle hot pressing at 1700 °C. After these two-step processings, [Si–Y–O–C–N] amorphous powders yielded a unique fine-grained microstructure composed of submicron grains with high aspect ratio.