Abstract
Effect of Y_2O_3 content on high temperature strength of crack healed specimen has been investigated. Furthermore, the crystallization by the addion of Y_2O_3 under different healing conditions has been investigated. The semicircular crack (average diameter; 100μm) was made in the center of specimen using Vickers hardness indenter. Bending strength was measured from room temperature(R.T.) up to 1300℃ by 3-point bending test system. The results showed that the bending strength of Mullite/SiC composite with Y_2O_3 increased compared with that of the monolithic Mullite. This tendency was similar to the fracture toughness value. By adding Y_2O_3 the bending strength of Mullite/SiC composite increased from R.T. to 1200℃. The decrease of bending strength at 1300℃ of Mullite/SiC composite by the addition of Y_2O_3 is due to glass phase of crack healing material.
