Development for Mesurment System on Impact Fracture Toughness of Ceramic Material at Elevated Temperature

一个新的仪器系统已经开发出用于测量陶瓷材料在提升温度到1200 C by impact test with free ends bend specimenone-point-bend specimen的影响）。该标本为Charpy型（宽6毫米，高8毫米，长50毫米），并悬挂在一对薄薄的陶瓷线程上，将其悬挂在该标本的末端表面上。因此，由于热量的降低，通常采取了一个支持结构可能被禁用或保持在最低限度。撞击力id提供了一个带有6 mm直径和1500 mm长度的坠落钢圆柱体，用于测量压力波历史和确定撞击力的一对半导体应变罩。既然threads是在影响的时刻被打破的，那么该物种就被允许以不受约束的方式与两者之间的约束分离，一个简单的公式被用于确定动态压力强度因子，以确定可测量的影响力。微型计算机是用来处理实验数据的。一系列如果影响测试已经被证明是以下降高度增加的研究结果和影响分数的测试数据的最低下降高度（导致的特定分数的最低下降高度）来确定。The Impact fracture toughness values of the ceramic specimens made of Silicon carbide（SiC）、Silicon nitride（I_3n_4）或partially stabilized zirconia（ZrO_2） were measured and the usefulness of the present system has been demonstrated。

A new instrumentation system has been developed for measutement of the impact fracture toughness of ceramic materials at the elebvated temperature up to 1200゜C by impact test with free ends bend specimenone-point-bend specimen). The specimen is of Charpy type(6mm widht, 8mm height and 50mm length) and hanged in an infrared image furnace by a couple of thin ceramic threads cemented onto the end surface of the specimen. Thus the heat counduction that usually take place through support structure can be avoided or kept to a minimum. The impact force id proveded by a falling steel cylinder of 6mm diameter and 1500mm length with a pair of semiconductor strain guages cemented onto a cylindrical surface to measure the stress wave history and hence to determine the impact force. Since the thin threads are thought to be broken at the moment of impact, the specimen is supposed to fracture with both ends free from constraint.A simple formula has been detived for determining the dynamic stress intensity factor from the measured impact force. A microcomputer is used for processing the experimental data. A series if impact tests has been performed with drop-height increased gradually and the impact fracture toughness was determined from the test data of the minimum drop-height that caused specimen fracture. The impact fracture toughness values of the ceramic specimens made of Silicon carbide(SiC), Silicon nitride(I_3n_4) or partially stabilized zirconia(ZrO_2) were measured and the usefulness of the present system has been demonstrated.