ABSTRACT
Fast heating rates as normally used in sintering lab samples was found to create difficulties in sintering large ZrO2–plates. While the outer region of the sample was densified the core showed a pronounced crack pattern. In spite of the low thermal conductivity temperature gradients could be excluded as a reason. Small samples were prepared out of the large green bodies which could be investigated by mercury porosimetry and which could undergo an unconstrained shrinkage in a dilatometer. The core had a 0.7% lower green density but the final density was found to be almost identical. As a consequence, the shrinkage of the core was higher. Being constrained in a large plate this difference in shrinkage causes the appearance of mismatch stresses between core and outside which then cause cracking. The use of a binder containing powder resulted in green bodies with a much better green density distribution, i.e. they could be sintered to almost full density and had a strength difference of only 3 % between outside and core.
