新的陶瓷缺口试件制备方法及其在断裂韧性测试中的应用

A New Method for Preparing Notched Specimens and Its Application to Measuring the Fracture Toughness of Ceramic Materials

利用模压注塑的方法制出陶瓷缺口试件生坯，然后烧结制成缺口试件。这种方法制备的缺口试件其缺口半径可按需要在很大范围内变化以供选用，其最小可达几μｍ；而且缺口光洁度一致性好；可以很好地用于陶瓷材料缺口强度和断裂韧性的测试。

In order to gain the true values of fracture toughness of ceramic materials, the radii of the single edged notched(SENB) specimens used in testing have to be smaller than three to five times the grain size of materials tested. The SENB specimens are normally machined with abrasive wheels and the notch width is larger than 0.2 mm. When using these specimens, the fracture toughness determined is higher than its true value. A new method for preparing the SENB specimens is developed in this investigation. A sharp notch is introduced during the specimencasting with a special mould and the notch radius of the sintered specimens is smaller than a few micrometers. Thus, the true values of fracture toughness of ceramic materials can be obtained. Moreover, by means of same process, the SENB specimens with different notch radii can be made. The test results show that the notched flexural strength measured with these specimens is more reproduceable and reliable.