常压固相烧结碳化硅陶瓷的表面裂纹及其对材料强度的影响(英文)  

Surface Cracks of Solid-phase-sintered Silicon Carbide Ceramics and Their Influeces on Material Strength

作　　者：杨晓[1] 刘学建[1] 黄政仁[1] 

机构地区：[1]中国科学院上海硅酸盐研究所,高性能陶瓷和超微结构国家重点实验室,上海200050

出　　处：《无机材料学报》2014年第4期438-442,共5页Journal of Inorganic Materials

摘　　要：采用压痕加载的方式在固相烧结碳化硅陶瓷材料的抛光表面分别加载维氏及努氏压头，获得不同形貌的表面裂纹，系统地研究了表面裂纹尺寸及裂纹倾斜角对材料强度的影响。实验结果表明，当尖锐的维氏裂纹尺寸约为10μm时，该裂纹开始主导材料的断裂过程并导致材料强度的下降，而维氏压痕约3μm左右时，材料的强度几乎不受影响。研究还表明，1-2N载荷下较小尺寸的努氏裂纹对材料强度具有一定的影响，但无规律性；5N以上载荷下尺寸较大的努氏裂纹在断裂过程中易发生偏转而主导材料的断裂，实验推导得出裂纹倾斜角目与相应的四点弯曲强度σ存在关系式：σ∝（sinθ）-1/2。The effects of surface cracks on bending strength of Solid-phase-sintered Silicon Carbide Ceramic （SSiC） were systematically investigated in aspects of crack size and inclined angle. The relation between the surface cracks and material strength revealed that the Vickers crack size is about 10 μm after 0.5 N indentation load that begins to dominant the fracture of SSiC test bars. Vickers cracks no larger than 3 μm are safe and do not harm to the general bending strength. It is found that inclined Knoop crack after 5 N or above is easier to deflect from the original direction and dominates the sample fracture process. And the relationship between the flexure strength σ and inclined angle θ is found to correspond with σ∝（sinθ）-1/2. When the indentation load is smaller than 1-2 N, Knoop crack plays a similar effect as intrinsic defect that they randomly dominate the sample fracture process; and this randomness makes the impact of inclined angle on the flexure strength irregularly.

关 键 词：SIC陶瓷 表面裂纹 裂纹倾斜角 材料强度 

分 类 号：TQ174[化学工程—陶瓷工业]