Plastic deformation of mullite/yttria composites

Mullite (3Al(2)O(3).2SiO(2)) based composites have excellent mechanical and thermal properties. The same characteristics that give mullite good resist ance to plastic deformation also make its sintering difficult. Yttria is on e of the most commonly used additives to reduce sintering temperatures in m ullite. Additionally vitreous silicates (Y2Si2O7) could improve ductility. In this work we have used mullite samples with various amounts of Y2O3 (0, 5 and 9 wt.%). Details of processing and characterization of these composit es have been the subject of a previous publication. We have compared the du ctility of these composites by means of compressive deformation tests at el evated temperatures. Creep tests were performed at temperatures between 130 0 and 1400 degreesC, in air, in a stress range of 0.69 to 34.5 MPa.