Shock Compression Behaviors and the Correlation with Microstructures of Ceramic Materials

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Ceramic materials are hard but brittle, and have large crystal anisotropy. The yielding and phase transition unser shock compression of ceramics strongly depend on their characterizations. In this study, the shock yielding property, high-pressure phase transition, equation of state, etc.of various kinds of ceramic materials ant the correlation with material characterizations were investigated by the shock-wave measurements and recovery experiments using high-quality specimens. The shock compression experiments were performed by using a powder gun of Kumamoto University, a two-stage light gas gun of Tohoku University and the high-velocity mirror-rotating type streak cameras.The elastoplastic transition, phase transition and EOS of the high-pressure phase of the cubic and tetragonal zirconia were studied, and the effects of crystal structure and crystal state were clarify. The anomalous Hugoniots and large spall property were found on the tetragonal zirconia, and the correlations with ph … More ase transition were discussed. The effects of microstructure on the strength were investigated on monolithic Si_3N_4 ceramics and the SiC whisker-doped ceramics. The Hugoniot compression curve of AIN was measured, and the elastoplastic transition and phase transition, equation of state and also the effect of crystal grain were studied. The jagged profiles of free-surface in elastic and plastic region were observed on B_4Cpolycrystal and Al_2O_3 single crystal, which indicated that cracks playd an important role in the elstoplastic transition. The anisotropic HEL of LiF single crystal was measured.The Hugoniot compression curves of ZnS and ZuSe were measured, and the phase transitions were confirmed on ZuS and ZnSe and a new phase transition was found on ZnS.The VISAR system (Laser-Velocity Interferometer) was produced ourselves, and the particle-velocity history of a steel was succeeded in measurement. In addition, a long pulsed YAG double frequency lase was also produced for the optical measurements. Less