Binder burn-out in a controlled single-mode microwave cavity

Abstract

Organic binders are added to provide sufficient green strength to an unfired ceramic body to permit handling and machining. However, the organic binders must be removed from the ceramic bodies prior to sintering at high temperature. The volatile products produced during binder burn-out can cause cracking if the binder is removed too quickly or if the sintering process (at high temperatures) begins before binder removal is complete. Several researchers have investigated microwave binder burn-out for ceramics. Moore et al. removed PMMA binder from PMMA/alumina compacts using conventional heating, microwave heating and microwave hybrid heating. 100% of the binder was removed from specimens ({le}24 grams, containing {le}8wt% binder) heated to 470 C with 3,200 Watts of microwave power. Yu et al. completed binder burn-out of tape cast barium strontium titanate ceramics using a single-mode microwave cavity at lower temperature and less time than in a conventional furnace. This study focuses on microwave binder burn-out of Al{sub 2}O{sub 3}/binder and Al{sub 2}O{sub 3}/SiC/binder systems in the single-mode cavity using: (1) fixed input power levels and (2) stepped input power level sequences.