IN-SITU CHARACTERIZATION OF THE SHRINKAGE BEHAVIOR OF CERAMIC POWDER COMPACTS DURING SINTERING BY USING HEATING MICROSCOPY

Heating microscopy, used as optical dilatometry, provides an advantage ous experimental method for characterizing in situ the sintering behav ior of ceramic powder compacts. It en ables the densification process to be monitored without the application of load, and thus, there is mi nimal interaction between the sintering sample and external constraint s. Ln this study, the application of the technique in studing the cons tant-heating-rate sintering of different ceramic powder compacts is sh own, focusing on assessing the isotropic or anisotropic shrinkage beha vior of the powder compacts investigated. All compacts were made from powders having similar (irregular) particle shapes and were obtained b y the same uniaxial compaction technique with the use of the same comp acting pressures. However, both mullite and yttrium disilicate powder compacts showed isotropic sintering behavior, whereas barium magnesium aluminosilicate glass powder compacts showed shrinkage anisotropy. Th e complexities in predicting the occurrence of shrinkage anisotropy du ring sintering and its variation with the progress of densification ar e outlined briefly. (C) Elsevier Science Inc., 1998.