DEVELOPMENT OF EVALUATION EQUIPMENT FOR INTERFACIAL FUNCTIONS OF CERAMIC BASE COMPOSITES

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Properties as high temperature creep, fracture toughness etc. of ceramic base composite is strongly affected by the interfacial bonding between fiber or whisker and matrix, however, there is no suitable way of direct measurement of interfacial bonding. The purpose of this research is to apply a stress into the composite introducing an interfacial shearing or debonding and then measure the internal friction to evaluatc the existence of interfacial debonding. Precisely speaking, (1) : development of the rigid joining fixer for measuring the amplitude dependency of the internal friction by torsion pendulum applicable at high temperature, (2) : Evaluation of the debonding behavior of the composite from the amplitude dependency, (3) : application of this technique to the carbon/carbon composite, (4) : Investigation of the application limit of the developed equipment. We succeeded in to develop a excellent equipment of internal friction tester with higher level of stress applicable. Following results were obtained ; (1) : The developed equipment was applicable up to 1500ﾟC and 2.5ﾟ as a maximum amplitude, which was higher than 270 MPa for MgO, (2) : The published data of C/C composite were collected, (3) : The internal friction data was correlated to the high temperature crecp data by applying the four elements model with springs and dash pots, (4) : In case of MgO polycrystalline materials, there were two peaks at 800ﾟC and 1200ﾟC,which were strongly dependent on the amplitude of the torsion exceeding the piers stress of the crystal. (5) : The viscosity of the interfacial glassy phase in silicon nitride ceramics can be estimated by the internal friction data.