The creep behavior study of α/ß-SiAlON ceramics

SiAlON ceramics are potential materials to be used for high temperature applications due to their good thermo-mechanical and chemical properties, but their uses have been limited so far. Creep performance of SiAlON will finally determine its use as high temperature components. The aim of the study was to investigate the high temperature bending creep behavior of ?/ß-SiAlON ceramics. The creep behavior of ?/ß-SiAlON ceramics was investigated by four-point bending creep tests under stresses from 50 to 150 MPa at temperatures from 1300°C to 1400°C in air. The role of the heat treatment, using different sintering additives (Y2O3, Er2O3) and addition of SiC particles on the creep performance of SiAlON ceramics were studied. Consequently, the degree of crystallization of grain boundary amorphous phases and intergranular phase chemistry depending on the type of sintering additive used for densifying of material have been found as the most important parameters effecting creep performance of these materials under existing test conditions. Considering SiAlON ceramics have similar creep prop¬erties as Si3N4, these materials promise more applicability than Si3N4 ceramics as high temperature components, because SiAlON ceramics can be fabricated easier and cheaper and offer more freedom than Si3N4 for tailoring to high temperature applications through changes in composition and heat treatment.