高温大気中におけるSiC繊維強化/SiC複合材料のクリープ・疲労破壊挙動と寿命予測

抄録

Application of SiC fiber reinforced/SiC matrix composites (SiC/SiC composites) to hot sections of aircraft engines has been expected for considerable improvement of the fuel efficiency. Aircraft engines are operated for long term, namely more than ten thousand hours, it needs to elucidate the rupture behavior of SiC/SiC composites under the combination of constant and cyclic tensile loads. This study investigated the damage mechanism of an orthogonal 3-D woven SiC/SiC composite under monotonic tension, constant tensile load, and cyclic tensile load at 1100°C in air.

As a result, it was revealed that the rupture strength and lifetime were strongly affected by the matrix crack propagation due to oxidation of the BN interface layers under monotonic and constant loads. Besides, under cyclic tensile loading, considerable strength reduction was observed. Single fiber push-out test result suggested that the decreased in the interfacial shear stress between fiber and matrix caused by wear. Lifetime prediction model under constant and cyclic tensile loads was proposed by considering both expansion of interface oxidation layers within load-bearing 0° yarn and interfacial shear stress degradation due to cyclic tensile load.