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On the Impact Strength Characteristics of Fine-Ceramics involving the Surface Damage by Repeated Impact Load.

涉及反复冲击载荷表面损伤的精细陶瓷的冲击强度特性。

基本信息

批准号：
62550061
负责人：
NAKAYAMA Hideaki
金额：
$ 1.34万
依托单位：
Faculty of Junior College of Automobile Industry, Osaka Sangyo University.
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

Engineering ceramics have two opposite aspects in their mechanical properties; low fracture toughness and high strength at high temperature together with excellent wear properties.In order to characterize the fracture toughness of fine ceramics, a series of experiments was carried out from two different points of view: One is impact 3-point bending test at room and high temperatures upto 1200゜c, and another is surface damage test by repeated impact load. The results of the former test were evaluated statistically. Brazed joints of ceramics/steel were used for the latter experiment considering the future application of ceramics. In this study were used three sorts of engineering ceramics; sintered silicon nitride, reaction sintered silicon carbide and alumina.Major conclusions of this study are summarized as follows: (1) Results of impact 3-point bending test at room thigh temperature: The impact bending strength of silicon nitride is higher than the static bending strength when compared at each temperature level. And further the scatter of strength under impact bending is almost the same as that of static bending. Thus, it is concluded that silicon nitride has excellent impact strength at high temperature. On the other hand, silicon carbide shows low impact strength at high temperature when evaluated at low failure probability. (2) Results of surface damage tests: Observations of surface damage of silicon nitride indicated that macro-cracks propageted radially from center of ceramics disc; the indentation by steel hammer.

工程陶瓷具有两种相反的力学性能，即断裂韧性低和高温强度高以及优异的耐磨性能。为了表征精细陶瓷的断裂韧性，从两个不同的角度进行了一系列实验：一个是在室温和高达1200 ℃的高温下的冲击三点弯曲试验，另一个是通过重复冲击载荷进行的表面损伤试验。对前一次试验的结果进行统计学评价。考虑到陶瓷的未来应用，陶瓷/钢的钎焊接头用于后一个实验。本研究以烧结氮化硅、反应烧结碳化硅和氧化铝三种工程陶瓷材料为研究对象，主要研究结果如下：（1）室温冲击三点弯曲试验结果：在各个温度水平下，氮化硅材料的冲击弯曲强度均高于静态弯曲强度。冲击弯曲强度的分散性与静态弯曲强度的分散性基本相同。因此，可以得出结论，氮化硅在高温下具有优异的冲击强度。另一方面，当在低失效概率下评估时，碳化硅在高温下显示低冲击强度。(2)表面损伤试验结果：氮化硅陶瓷表面损伤观察表明，宏观裂纹从陶瓷圆盘中心向径向扩展;