Developments of Ultra High Temperature-Extensometer and High Temperature Inelastic Design Method of Ceramics Using It

在本研究中，我们开发了能够准确评估陶瓷在高温下推拉循环疲劳强度的测试系统。该试验系统由闭环式电液试验系统、以KANTHAL SUPER 33为加热器的电炉和采用ni基耐热高温合金新设计的水冷式试样夹持装置组成。利用该试验系统，成功地完成了烧结氮化硅陶瓷在室温~ 1200℃范围内的推拉循环疲劳试验。此外，我们还设计了用于测量陶瓷在高温下的拉伸和压缩变形的新型延伸计。在应力速率控制的三角形应力波作用下，用该伸长仪测量了烧结氮化硅陶瓷的室温拉伸和压缩位移。杠杆式拉伸计被证明是有用的测量拉伸和压缩位移在室温下具有足够的精度。

In the present study, we developed the testing system for evaluating accurately the push-pull cyclic fatigue strength of ceramics at elevated temperatures. This system was composed of the closed loop type-electrohydraulic testing system, the electric furnace with the KANTHAL SUPER 33 as a heater and the water-cooled specimen gripping device which was newly designed with the Ni-based heat-resisting super alloy The push-pull cyclic fatigue tests were successfully performed for the sintered silicon nitride ceramics in the temperature range from room temperature to 1200ﾟC by means of this testing system.Furthermore, we designed the new extensometer for measuring tensile and compressive deformations of ceramics at elevated temperatures. The tensile and compressive displacements of sintered silicon nitride ceramics were measured by means of this extensometer under stress rate-controlled triangular stress wave at room temperature. The lever-type extensometer proved to be useful for measuring tensile and compressive displacements with sufficient precision at room temperatures.