Full-field characterization of thermal diffusivity in continuous-fiber ceramic composite materials and components
Full-field characterization of thermal diffusivity in continuous-fiber ceramic composite materials and components
复制标题
连续纤维陶瓷复合材料和部件热扩散率的全场表征
DOI：
10.1117/12.204856
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
S. Rothermel
中科院分区：
文献类型：
--
作者：
J. S. Steckenrider;W. Ellingson;S. Rothermel
目前正在开发用于各种高温应用的连续纤维陶瓷基复合材料（CFCC），包括用于先进的热机。此类应用感兴趣的材料类别包括碳化硅 (SiC) 纤维增强 SiC (SiC(f)/SiC)、SiC 纤维增强氮化硅 (SiC(f)/Si3N4)、氧化铝 (Al2O3) 纤维增强 Al2O3 (Al2O3(f)/Al2O3) 等。在此类复合材料中，界面（纤维和基体之间）的状况对于组件的机械和热行为至关重要（裂纹、孔隙等传统机械缺陷也是如此）。例如，该界面（尤其是碳涂层纤维上）的氧化会严重降低机械性能和热性能。此外，热冲击损伤会通过大量裂纹的产生而使基体退化。因此，一种可用于评估界面状况、热冲击损伤以及检测其他“缺陷”的无损评估方法将非常有益，特别是如果适用于全尺寸部件。正在开发的一种方法使用红外热成像，通过测量热扩散率对大型部件的热性能分布进行“单次”全场评估。通过应用数字图像滤波、插值和最小二乘估计技术来降低噪声，我们可以实现几分钟或更短的采集和分析时间，并具有亚毫米空间分辨率。阿贡国家实验室开发的系统已用于检查一系列测试样本中热冲击、氧化处理、密度变化和抗氧化涂层变化的影响。具有非平面几何形状的小尺度 CFCC 组件也针对制造引起的热性能变化进行了研究。
Continuous-fiber ceramic matrix composites (CFCCs) are currently being developed for various high-temperature applications, including use in advanced heat engines. Among the material classes of interest for such applications are silicon carbide (SiC)-fiber-reinforced SiC (SiC(f)/SiC), SiC-fiber-reinforced silicon nitride (SiC(f)/Si3N4), aluminum oxide (Al2O3)-fiber-reinforced Al2O3 (Al2O3(f)/Al2O3), and others. In such composites, the condition of the interfaces (between the fibers and matrix) are critical to the mechanical and thermal behavior of the component (as are conventional mechanical defects such as cracks, porosity, etc.). For example, oxidation of this interface (especially on carbon coated fibers) can seriously degrade both mechanical and thermal properties. Furthermore, thermal shock damage can degrade the matrix through extensive crack generation. A nondestructive evaluation method that could be used to assess interface condition, thermal shock damage, and to detect other `defects' would thus be very beneficial, especially if applicable to full-scale components. One method under development uses infrared thermal imaging to provide `single-shot' full-field assessment of the distribution of thermal properties in large components by measuring thermal diffusivity. By applying digital image filtering, interpolation, and least-squares-estimation techniques for noise reduction, we can achieve acquisition and analysis times of minutes or less with submillimeter spatial resolution. The system developed at Argonne National Laboratory has been used to examine the effects of thermal shock, oxidation treatment, density variations, and variations in oxidation resistance coatings in a full array of test specimens. Subscale CFCC components with nonplanar geometries have also been studied for manufacturing-induced variations in thermal properties.