Three techniques for fracture toughness measurements on zirconia toughened ceramics were evaluated: the notched beam (NB) technique, the indentation fracture (IF) technique and the indentation strength in bending (ISB) technique. Using these techniques comparative measurements were performed on samples prepared by pressing (uniaxial) and sintering of four commercially available powder types. These were: Toyo Soda (Japan) powders with the designations TZ3Y (2,86 mole% Y2O3), TZ3YA (2,77 mole% Y2O3, 0,1 wt% A12O3) and TZ3Y20A (2,88 mole% Y2O3, 20 wt% A12O3) and a powder supplied by viking Chemicals (Denmark) designated as YP5Z-2.5 (2.5 mole% Y2O3). The measurementsshowed that similar Klc values were obtained with the IF- andISB-techniques, which therefore are recommended for Klcmeasurements. Too high values were, however, obtained with theNB-technique which therefore cannot be recommended. Finally,the measurements showed that a high temperature annealing is recommended prior to testing for the IF-technique.
|Place of Publication||Roskilde|
|Publisher||Risø National Laboratory|
|Number of pages||20|
|Publication status||Published - 1987|