Controlled drying to enhance properties of technical ceramics

The drying kinetics of several technical ceramics such as alumina, bochmite and lead zirconate titanate (PZT) have been determined in order to maximise significant properties relative to their use for fuel cell tubes, catalyst supports and as components in hydrophones and multi-phase actuators, Common to all materials investigated is the need to avoid macro-cracking within the green ceramic precursor prior to sintering. Avoidance of this problem is achieved by optimising the temperature and relative humidity conditions for drying. Such controlled drying permits shrinkage to occur without the development of any gross macro-cracking, as evidenced by the examination of the microstructure of sintered materials. The experimental work that has established the utility of controlled drying as an essential step in producing high quality ceramics has involved the detailed analysis of drying rate data and its correlation with shrinkage which has been monitored using digital camera imaging. Such an understanding of the drying process will contribute to the production of a wide range of high quality defect-free ceramic components by the most cost-effective route. (C) 2002 Elsevier Science B.V. All rights reserved.