Crack Growth Mechanism in Structural Ceramics and Microstructural Analysis

结构陶瓷中的裂纹扩展机制及微观结构分析

• 批准号: 07650778
• 负责人: SUGANO Mikio
• 金额: $ 1.34万
• 依托单位: Yamagata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650778/
• 关键词: Silicon Nitride; Zirconia; Crack growth mechanism; Three point bending strength; Fracture toughness; Strength at elevated temperature; Cyclic fatigue; Microstructural analysis; 破壊靱性; 高温強度異方性; 微構造

Microstructures of the process zone and the process zone wake which are developed around growing cracks were studied by scanning and transmission electron microscopy. The results obtained are as follows.1) The anisotropy of bending strength (sigma_b) and fracture toughness (K_<IC>) in hot-pressed (HP) Si_3N_4 ceramics has been studied at room temperature to 1573 K.Specimens were cut out parallel (HP-LS,HP-LT) and perpendicular (HP-SL,HP-ST) to the hot-pressing direction. The chevron notched beam method was employed for the K_<IC> measurement and the three-point bending test for obtaining the sigma_b. The anisotropy was found in the K_<IC> at the testing temperature up to 1073 K,but hardly at 1473 K.However, it reappeared at 1573 K remarkably. In the sigma_b this was discernible up to 1473K,although differences between the HP-LT and the HP-ST specimens decreased with increasing temperature and diminished at 1573 K.The results obtained were discussed in connection with the orientation of elongated beta-phase grains, comparing with those of pressureless sintered (PLS) specimens.2) The effects of temperature on bending strength and fracture toughness of zirconia ceramics have been studied in connection with microstructural changes in the process zone wake of a crack. Three point bending and fracture toughness measurement tests have been carried out at room temperature, 873 and 1273K.Microstructures in the vicinity of cracks and on fracture surfaces were examined by SEM,TEM and X-ray diffraction techniques. At the higher temperatures the three-point bending strength and the K_<IC> values decreased to about one third of that at room temperature. The stress induced phase transformation from tetragonal structure to monoclinic one has occurred more greatly at room temperature than at the higher temperatures. In the case of cyclically fatigued specimens, microstructures developed around fatigue cracks have also been studied by SEM and TEM techniques.

通过扫描和透射电子显微镜研究了在生长裂纹周围形成的加工区和加工区尾流的微观结构。所得结果如下：1)研究了热压(HP)Si_3N_4陶瓷在室温至1573K下的弯曲强度(sigma_b)和断裂韧性(K_<IC>)的各向异性。平行切取试样。 （HP-LS、HP-LT）和垂直于热压方向（HP-SL、HP-ST）。采用人字形缺口梁法进行K_<IC>测量和三点弯曲试验以获得sigma_b。在测试温度至1073 K时，K_<IC>均表现出各向异性，但在1473 K时几乎没有发现各向异性，但在1573 K时又明显再现。在 sigma_b 中，这一点在 1473K 之前都可以辨别，尽管 HP-LT 和 HP-ST 样本之间的差异随着温度的升高而减小，并在 1573K 时减小。所获得的结果与拉长的 β 相晶粒的取向有关，进行了讨论，与无压烧结（PLS）样品进行比较。2）研究了温度对氧化锆陶瓷的弯曲强度和断裂韧性与微观结构变化的影响在裂纹的加工区中。在室温、873K和1273K下进行了三点弯曲和断裂韧性测量试验。通过SEM、TEM和X射线衍射技术检查了裂纹附近和断口表面的显微组织。在较高温度下，三点弯曲强度和 K_<IC> 值降低至室温下的约三分之一。应力诱导的从四方结构到单斜结构的相变在室温下比在较高温度下发生得更大。对于循环疲劳样本，还通过 SEM 和 TEM 技术研究了疲劳裂纹周围形成的微观结构。

项目成果

菅野幹男他: "Si_3N_4焼結体の高温強度特性" 日本機械学会・平成7年度材料力学部門講演会講演論文集. Vol.B. 331-332 (1995)

Mikio Kanno 等：“Si_3N_4 烧结体的高温强度特性”日本机械工程学会论文集 1995 年材料力学分部讲座第 331-332 卷（1995 年）。

Mikio Sugano, Tadaaki Satake and Rikiya Ishikawa: "The Effects of Atmosphere on Fatigue Crack Growth Behavior in Zirconia" Proc.of the 1996 Annual Meeting of JSPE Tohoku Chapter. 69-71 (1996)

Mikio Sugano、Tadaaki Satake 和 Rikiya Ishikawa：“大气对氧化锆疲劳裂纹扩展行为的影响”，JSPE 东北分会 1996 年年会会议记录。

菅野幹男他: "ジルコニア薄板材の疲労き裂進展挙動に及ぼす雰囲気の影響" 精密工学会東北支部学術講演会講演論文集. 69-70 (1996)

Mikio Kanno等人：“气氛对氧化锆薄板材料的疲劳裂纹扩展行为的影响”日本精密工程学会东北分会学术会议记录69-70（1996）。

菅野幹男他: "ジルコニア焼結体のき裂進展挙動と微構造" セラミックスの破壊力学に関するシンポジウム講演論文集. 96-52. 68-71 (1996)

Mikio Kanno 等人：“氧化锆烧结体的裂纹扩展行为和微观结构”陶瓷断裂力学研讨会论文集 96-52 (1996)。

Mikio Sugano, Rikiya Ishikawa, Makoto Ebina and Tadaaki Satake: "Fatigue Crack Growth Behavior of Zirconia Thin Plates under Alternate Plane Bending" Proc.of the 1996 Annual Meeting of JSME/MMID. Vol.B,96-10. 413-414 (1995)

Mikio Sugano、Rikiya Ishikawa、Makoto Ebina 和 Tadaaki Satake：“交替平面弯曲下氧化锆薄板的疲劳裂纹扩展行为”JSME/MMID 1996 年年会会议记录。