Effects of heat-treatment conditions in the preparation of aluminum silicate fiber-based ceramic filter element for hot-gas filtration

Abstract

Aluminum silicate fiber-based ceramic filter elements were prepared using different drying methods and calcination temperatures. The effects of these parameters on the performance, including the microstructure, bulk density, shrinkage, flexural strength, and pressure drop, were investigated. The results indicated that there were differences in the microstructures of the filter elements fabricated via three drying methods and that the microstructure significantly affected the flexural strength and initial pressure drop. Compared with blast and vacuum drying, microwave drying inhibited the migration of the binder, improving the structural uniformity and mechanical strength. The filter element effectively removed particles with a size of >1 μm and exhibited a good regeneration performance. Furthermore, owing to the crystallization of fibers after calcination at 1000 °C, the density and shrinkage of the sample were significantly increased and the initial pressure drop was reduced. The mechanical strength was significantly reduced after calcination at 800 and 1000 °C. As the calcination temperature increased, the filter element gradually became brittle. Therefore, the optimal calcination temperature of 600 °C was important for obtaining an excellent filter element with a high flexural strength and low pressure drop.