SiC/SiCモデル複合材料の引張・界面強度特性評価

Tensile and interfacial strength evaluation of SiC/SiC model composites

小沢 和巳; 野澤 貴史; 谷川 博康

Ozawa, Kazumi; Nozawa, Takashi; Tanigawa, Hiroyasu

繊維表面の熱分解界面相厚さが240, 1150nmである多層被覆界面を施した一方向繊維(Hi-Nicalon Type-S)強化ミニコンポジット(TypeS-240, TypeS-1150)に対し、除負荷/再負荷サイクル引張試験を実施した。TypeS-240, TypeS-1150の複合材料中の有効繊維束強度は元来の79-104%, 70-85%であった。ヒステリシスループ解析の結果からは、TypeS-1150はTypeS-240の約0.7倍の界面摩擦応力を示し、単繊維押し抜き試験でもこの界面摩擦応力の界面相厚さ依存性が確認できた。これらのミニコンポジットはともに擬延性破壊挙動を示したが、TypeS-1150は低い界面摩擦応力が原因で複合材料中にて元来の繊維束強度を発揮できなかったと考えられる。

Tensile and interfacial properties of unidirectional SiC/SiC model composites reinforced with Hi-Nicalon Type-S fibers with innermost pyrolytic carbon (PyC) layer thickness of 240 and 1150 nm (TypeS-240 and TypeS-1150, respectively) were evaluated by unloading/reloading cyclic tensile tests and single fiber push-out tests. Effective fiber bundle strength in the TypeS-240 and -1150 composites were 79-104% and 70-85%, compared with the original fiber bundle strength. According to the analytic results using hysteresis loops of tensile curves, interfacial sliding stress of the TypeS-1150 estimated to be about 0.7 times as large as the TypeS-240. This tendency was also confirmed by the single fiber push-out tests. These composites showed quasi-ductility, but it is considered that the composite with the thicker interphase could not achieve its fiber bundle strength, probably due to the lower interfacial sliding stress.