Study on Strength and Fatigue of Ceramic Materials

为了弄清控制陶瓷多晶强度和疲劳的晶界行为，研究了与晶界结构相似的非晶材料的性能。结果表明：(1)明确了稀土氧化物助烧结体系的玻璃形成区域，并测定了其变形和结晶温度。(2)测定了非晶态材料在<Si_3> <N-4> Si <O_2> -CaO体系中的粘度、密度、硬度和热膨胀率。(3)对Ti <O_2> -Si <O_2>、Zr <O_2> -Si <O_2>和<A1_2> <O_3> -Si <O_2>体系的非晶态材料进行了结构和性能测试，发现了一些阳离子的异常配位态。(4)建立了测定多组分玻璃化学键强度的实验方法，并与理论结果进行了比较。(5)基于玻璃的实验数据，考察了化学成分、配位数、结晶、塑性变形和不均匀性对玻璃弹性模量和断裂韧性的影响，探讨了提高玻璃韧性的可能性。

In order to clarity the behavior of grain boundary, which controls the strength and fatigue of ceramic polycrystals, the properties of amorphous materials having similar structure to that of grain boundary were investigated. The following results were obtained: (1) The glass-forming regions were clarified for the systems containing rare-earth oxides being used for sintering aid, and furthermore their deformation and crystalline temperatures were determined. (2) Viscosity, density, hardness and thermal expansivity were determined for the amorphous materials in the <Si_3> <N-4> Si <O_2> -CaO system. (3) The amorphous materials obtained by RF-sputtering for the systems Ti <O_2> -Si <O_2> , Zr <O_2> -Si <O_2> and <A1_2> <O_3> -Si <O_2> were examined for their structure and properties, and some abnormal coordination states of cations were found. (4) The experimental ways to determine the chemical bond strength were established for multi-component glasses and the results were compared with the theoretical ones. (5) The effects of chemical composition, coordination number, crystallization, plastic deformation and inhomogeneity on elastic moduli and fracture toughness were examined based on the experimental data for glass and a possibility to increase the toughness was discussed.