Abstract: | Three techniques for the determination of KIc in Ce-stabilized ZrO2/Al2O3 composites have been evaluated: the single-edge-notched beam (SENB); the indentation strength in bending (ISB) and the indentation fracture (IF). Comparative measurements, performed on samples prepared by sintering uniaxially pressed powders obtained by a chemical route, showed that whatever the technique used, KIc increased as the Al2O3 grain size decreased. The three methods give similar results if some procedural improvements are introduced, namely: (i) the polished samples are annealed prior to testing: (ii) a more reproducible notching technique would be developed for the SENB method; and (iii) the crack shape and length are known exactly in the IF technique. In the IF test, the crack shape profile is of Palmquist type at low indentation loads while a transition to a half-penny-shaped crack occurs at higher loads. |