Collaborative Research: Oxidation of Ultra-High Temperature Ceramic (UHTC) Composites in Dissociated Oxygen Environments

SRI国际和范德比尔特大学之间的这项研究合作将系统地研究氧离解对超高温陶瓷（UHTC）复合材料及其组分的高温氧化的影响。 ZrB_2/SiC和HfB_2/SiC超高温复合材料具有较高的熔点和良好的高温尺寸稳定性，是高超声速飞行器前缘和控制面的理想材料。 研究将特别关注原子氧对（1）被动和主动氧化机制之间的边界，（2）被动和主动氧化的动力学，以及（3）所得氧化物层的组成，形态和光学特性的影响。 氧化实验将在SRI的一个真空室中进行，该真空室配备了用于产生原子氧的高功率微波放电和用于样品加热的CO2激光器，以及独特的实验室规模的电弧喷射设施。 原位诊断将包括基于激光和质谱的物种检测，用于监测气态反应物和产物的存在和浓度。 氧化后表面分析将在范德比尔特大学进行，使用各种表征技术来检查氧化层的成分、结构和光学特性。 UHTC复合材料独特的高温性能可以使高超音速飞行器设计具有尖锐的前缘-设计具有比传统钝体高超音速飞行器更大的飞行能力。 研究结果将有助于加深对UHTC在游离氧环境中氧化行为的基本认识，并为UHTC部件在高超声速飞行器上的应用铺平道路。 SRI和范德比尔特之间的合作也将为本科生和研究生创造重要的教育和研究机会，他们将参与该计划的所有阶段。该项目与AFOSR（6.1）共同资助。

This research collaboration between SRI International and Vanderbilt University will systematically investigate the influence of oxygen dissociation on the high temperature oxidation of ultra-high temperature ceramic (UHTC) composites and their constituents. Due to their high melting points and good dimensional stability under intense aerothermal heating, ZrB2/SiC and HfB2/SiC UHTC composites are very promising for sharp leading edge and control surface components of hypersonic vehicles. Research will specifically focus on the effects of atomic oxygen on (1) the boundaries between passive and active oxidation regimes, (2) the kinetics of passive and active oxidation, and (3) the composition, morphology, and optical properties of resulting oxide layers. Oxidation experiments will be conducted at SRI in a vacuum chamber equipped with a high-power microwave discharge for producing atomic oxygen and a CO2 laser for sample heating, as well as in a unique laboratory-scale arc-jet facility. In situ diagnostics will include laser-based and mass spectroscopic species detection for monitoring the presence and concentrations of gaseous reactants and products. Post-oxidation surface analyses will be performed at the University of Vanderbilt using a variety of characterization techniques to examine the composition, structure, and optical properties of oxide layers. The unique high temperature properties of UHTC composites can enable hypersonic vehicle designs with sharp leading edges - designs with much greater flight capabilities than traditional blunt-body hypersonic craft. The results of this study will advance the fundamental understanding of UHTC oxidation behavior in dissociated oxygen environments and help pave the way for the application of UHTC components on hypersonic vehicles. The collaboration between SRI and Vanderbilt will also generate significant educational and research opportunities for undergraduate and graduate students, who will participate in all phases of the program.This project is co-funded with AFOSR (6.1).