SiC繊維強化Si_3N_4複合焼結体破壊挙動のその場観察

概要

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Fracture behavior of 15vol% SiC fiber (SCS-6 Φ 140μm; AVCO Specialty Materials Div., U.S.A) reinforced Si3N4 composite materials was directly observed with an in-situ observation apparatus composed of bending machine and scanning electron microscope. When load is applied to a notched specimen, a crack initiates from the bottom of the notch and propagates in the specimen non-catastrophically, because the crack propagation is stopped successively at the fibers. With further increase of the load, the crack elongates and halts over again and again, and finally propagates along the fibers. Fatigue crack growth was not detected after 100 times of cyclic load application with a constant strain rate and 300 times application of impact load, when the maximum applied stress of the cyclic loading is less than 75% of the maximum bending strength of notched specimens. In the cyclic loading process, moreover, it was observed that the crack width becomes wide and narrow on loading and unloading, respectively.
社団法人日本セラミックス協会の論文
1987-09-01