抄録
Advanced Pore-Free SiC (APF-SiC) with super-high strength is developed by reaction sintering method improved newly. Authors had constructed a peculiar fracture mechanism model of this material differing from the fracture mechanism of usual ceramics. The fracture mechanism is that fracture occur at cluster crack (one of the formed some clusters). This fracture is called cluster fracture. In this study, to clarify adequacy of this model, clusters were researched in detail by using mapping analysis and observing some clusters. Crack growth behavior is researched by using AE censer. As the results, it is clarified that some clusters are formed by aggregate of un-reacted substance and the cluster fracture doesn't occur due to growth of cluster crack. In the case of 4-point bending tests is carried out at low loading rate, nonlinear behavior appeared on stress-strain curve before failure. In addition, bending strength increased with decreasing loading rate. On the basis of these results, fracture mechanism is considered as follows. Some clusters are formed by aggregate of un-reacted substance at near rupture. Cluster fracture occurs at the same time with cluster crack being one of the formed some clusters are formed. Therefore increasing strength is because to forms cluster crack stops by internal energy accumulated by loading was released since residual metallic silicones are preferentially failed.
