Fracture behaviour of Mg-PSZ ceramics: Comparative estimates

The mechanical behaviour of different Mg-PSZ ceramics is studied. Results of their edge fracture (EF) and single edge V-notch beam (SEVNB) tests are discussed. These inelastic ceramics exhibit nonlinear relations between the fracture load and the distance from the extreme point on the chip scar to the specimen edge. They also possess nonlinearly rising R-lines. It is established that the data points plotted in the EF base diagram fall below the baseline (lower barrier to the onset of fracture). By projecting these data points onto the baseline, fracture toughness values close to those of the matrix are determined. The limitations of conventional procedures for evaluating the mechanical behaviour of these ceramics were found out. It has been demonstrated that the EF test method can be quite adequate for enhancing the reliability of comparative fracture resistance estimates.