Formation of intergranular amorphous films during the microstructural development of liquid phase sintered silicon carbide ceramics
Journal
Journal of Materials Science
Journal Volume
39
Journal Issue
13
Pages
4095-4101
Date Issued
2004
Author(s)
Abstract
The microstructure of liquid phase sintered SiC ceramics was characterised by means of high resolution transmission electron microscopy (HRTEM). The SiC ceramics were pressureless sintered with the additions of Al2O 3 and Y2O3 at sintering temperatures of 1800 and 1950°C, respectively. At a sintering temperature of 1800°C the microstructure of the SiC ceramics has no crystallised secondary phase and the SiC grains are separated by an intergranular amorphous film. In contrast, in the case of the microstructure of SiC ceramics sintered at 1950°C a clean interface without any amorphous layer between the SiC grains was observed. The secondary phase is crystallised into the Y3Al5O 12 phase and exhibits a clean interface between the SiC grains. An explanation for the existence or the absence of the intergranular glass films are given by an extended Clarke's model of the force balance of attractive van der Waals forces and repulsive steric forces. The chemical decomposition of the intergranular glass film at elevated temperature was considered. © 2004 Kluwer Academic Publishers.
Type
journal article