2535 High-temperature Mechanical Properties of Machined Si_3N_4/SiC Composite Treated by Crack-healing
Details
The crack-healing behavior of the machined cracks in Si_3N_4/20wt% SiC composite was investigated. The addictive powders are used the 5wt.%-Y_2O_3+3wt.%-Al_2O_3. The machined cracks were introduced by the machining, during make a semicircular groove on the center of specimen. The machined specimens were healed in various temperatures and time in air. The optimized crack-healing conditions were found to be temperature of 1300℃ and time of 1h, because the machined specimen healed under this condition exhibited almost same strength as the smooth specimen healed. Moreover, the high-temperatures strengths (<1300℃) exhibited similar properties to the Vickers indented crack-healed specimen. It can be demonstrated that the crack-healing was useful for an increase in the strength of the machined ceramics, economically.
