Formation mechanisms of processing defects and their relevance to the strength in alumina ceramics made by powder compaction process

摘要

With new characterization techniques, the structuresof green and sintered bodies were examined in great detail tounderstand the formation mechanism of potential fracture originsin alumina ceramics made by the powder compaction process.Large pores, which are found at many fracture origins, wereformed in green bodies through two mechanisms. One is createdfrom the dimple in the powder granules and the other frominadequate cohesionof the granules. Another potential cause offracture, the large grains, developed from large particles in thegreen body. The concentration especially of large pores was foundto be quite high. This is clearly responsible for the moderatestrength with high Weibull's modulus of the alumina ceramicexamined in this study.