MICROSTRUCTURE AND CREEP-PROPERTIES OF ALUMINA ZIRCONIA CERAMICS/

High temperature creep of two zirconia roughened alumina ceramics, fab ricated by powder processing and sol-gel precursors processing, has be en studied in order to determine plastic determine mechanisms. Compres sive creep tests were carried out between 1300 and 1450 degrees C, tin der stresses from 10 to 150 MPa. For the sample fabricated from powder s, a stress exponent of 1.4 and an activation energy of 580 kJ/mol wer e found below a critical stress of 40 MPa. For larger stresses, accele rated creep rates developed. In the specimens processed from precursor s, values of 1.8 for the stress exponent and 540 kJ/mol for the activa tion energy, over the entire range of stresses have been determined Cr eep parameters and microstructural evolution of the samples during the experiments have been correlated with models to establish the dominan t creep mechanism.