PREDICTION OF FRACTURE IN SINTERING OF CERAMIC POWDER COMPACT

A criterion for predicting fracture initiation due to non-uniform shri nkage in sintering of ceramic powder compacts is proposed. In the pres ent criterion, the occurrence of sintering fracture is evaluated by us ing the difference in volumetric strain between non-uniform and unifor m shrinkages because the stress is induced by the difference in volume tric strain during sintering. The material constants in the criterion are determined from a sintering test using ringed compacts under restr iction of the shrinkage. Non-uniform shrinkage behaviour due to the de nsity distribution in sintering of circular plates and rings with a bo ss is simulated by the viscoplastic finite element method, and the occ urrence of sintering fracture is predicted from the calculated results by the use of the criterion. The predicted fracture rates and sites f or the sintered products are in good agreement with the experimental o nes for alumina compacts. (C) 1997 Published by Elsevier Science Ltd. All rights reserved.