U.S.-Germany Cooperative Research on Stress-Induced Transformation and Crack Growth in Partially-Stabilized Zirconium Oxide-Based Ceramics

该奖项将支持凯斯西部储备大学的Arthur Heuer博士和德国Julich KFA Fur Reaktorwerkstoffe研究所的Rolf Steinbrech博士在陶瓷领域的合作研究。该项目的目的是研究氧化锆应力诱导相变和裂纹扩展。在过去的十年里，氧化锆质陶瓷的相变增韧一直是科学和技术研究的热点，因为这些材料在严酷的疲劳和高温暴露条件下具有潜在的工业应用价值。这一时期的主要发现之一是“阻力曲线”(R曲线)行为的重要性。在这个项目中，将研究单调和低周疲劳、环境对室温下自然裂纹行为的影响以及预裂(“远场”)应力诱导的相变。断裂力学测试将主要在朱利奇进行。克利夫兰的工作将侧重于断裂力学测试试件的微观结构特征和测试后相变区的确定，这两项都是Heuer博士的专长。此外，还将利用低电压扫描电子显微镜、光学干涉测量和显微拉曼光谱，在没有微裂纹的情况下进行涉及相变的现场测试。该项目将受益于两位研究人员过去成功合作的历史，以及他们在断裂力学和微观结构表征方面的互补专业知识。

This award will support collaborative research in ceramics between Dr. Arthur Heuer, Case Western Reserve University, and Dr. Rolf Steinbrech, Institut fur Reaktorwerkstoffe, KFA, Julich, Germany. The objective of the project is to investigate stress-induced transformation and crack growth in zirconia. Transformation toughening in zirconia-containing ceramics has been an area of intense scientific and technological interest during the past decade, in view of the potential industrial applications of these materials in demanding conditions of fatigue and high temperature exposure. One of the major findings during this period has been the importance of "resis- tance-curve" (R-curve) behavior. In this project, monotonic and low cycle fatigue, environmental effects on natural crack behavior at room temperature, and pre-cracking ("far-field") stress-induced transformation will be studied. The fracture mechanics testing will largely be conducted in Julich. The work in Cleveland will emphasize microstructural characteri- zation of the fracture mechanics test specimens and the determination of transformation zones after testing, both specialties of Dr. Heuer. In addition, in situ tests will be carried out involving transformation in the absence of microcracking, using low voltage SEM, optical interferometry, and micro-Raman spectroscopy. The project will benefit from the past history of successful collaboration between the two investigators and their complementary expertise in fracture mechanics and microstructural characterization.