Digital Repository, ECF14, Cracow 2002

Font Size: 
Fatigue Strength of Crack-Healed Si3N4 at Elevated Temperature

Last modified: 2013-02-10


Si3N4/SiC composite ceramics were sintered to investigate their fatiguestrength behavior after crack healing. Y2O3 and Al2O3 powders were added as sinteringadditives to enhance the sintering properties. A three-point bending specimen (sized 3~4~40mm) was hewed out from a sintered compact obtained according to the JIS standard.Semi-circular surface cracks of about 100ƒÊm and 200ƒÊm were made on the center of thetension surfaces of three-point bending specimens using a Vickers indenter. Aftercrack-healing processing at 1200Ž and 1300Ž for 1 hr. in air, the cyclic and staticfatigue strength behavior of these crack-healed specimens were determined systematicallyat high temperatures of 800Ž, 1000Ž, 1200Ž, and 1300Ž. The Si3N4/SiC compositeceramics were shown to possess remarkable crack-healing ability, and the crack-healedspecimens showed cyclic and static fatigue strength behavior similar to smooth specimensat high temperatures as well as at room temperature. The crack-healed zones had sufficientfatigue strength even in a high-temperature environment, and most fractures occurredoutside the pre-cracked zone in those crack-healed specimens.

Full Text: PDF