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In situ Determination of Phase Equilibria in the Quaternary Hafnia-Tantala-Titania-Tungstate System

第四纪铪-钽-二氧化钛-钨酸盐体系中相平衡的原位测定

基本信息

批准号：
1838595
负责人：
Waltraud Kriven
金额：
$ 63.44万
依托单位：
University of Illinois at Urbana-Champaign
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1838595&HistoricalAwards=false
关键词：
situ Determination Phase Equilibria Quaternary

项目摘要

NON-TECHNICAL DESCRIPTION: This project addresses the need for a new, more efficient way to elucidate and measure very high temperature (HT) diagrams of phases or different forms existing under specific conditions of temperature and composition called "phase diagrams" in oxide ceramics. Current methods are slow and based on heating ceramics at high temperatures, cooling them and measuring them at room temperature (RT). However, we do not know that the phase or form observed at RT is the same as what existed at HT. Within this project, new experimental tools have been developed enabling measurements to be made at temperatures up to 3400 C, thereby providing correct and accurate basic scientific knowledge. It is transformational to understand that such ceramic phase diagrams could be determined expediently in a short timeframe. The same techniques can be widely used to make significant and rapid advances in the underlying solid state physics and chemistry knowledge, so as to identify the next generation of complex materials for devices. Both undergraduate and graduate students trained in this research may be subsequently employed in the aircraft design and manufacturing sector, or as basic science researchers, particularly at high intensity, synchrotron X-ray laboratories. Outreach to high school students and teachers is also carried out. This research is relevant to identifying ceramic materials for space exploration and next generation electronic devices. TECHNICAL DETAILS: This research demonstrates a method by which the quaternary, tantala-hafnia-titantia-tungstate (Ta2O5 - HfO2 - TiO2 -WO3) phase diagram can be measured in situ, at temperatures up to 3400 C, in air or under controlled atmospheres. This work combines experimental techniques of (i) homogeneous powder synthesis by the organic steric entrapment method (ii) the quadrupole lamp furnace capable of 2000 C in air and (iii) the conical nozzle levitator capable of 3400 C in controlled atmospheres. Techniques (i) and (ii) were invented at the University of Illinois Urbana- Champaign and (iii) was developed and refined by two small companies. In addition, this research has resulted in theoretical modeling techniques to explore mathematical lattice correspondences for orientation relationships between crystal structures as they change with temperature (thermal expansions, phase transformations, invariant reactions) as well as across compositional ranges. These approaches will be applied to the four-component phase diagram constituting the quaternary system. Alongside the development of experimental and theoretical techniques that are being developed, graduate students are being fully trained, i.e. the scientists of the future. In turn, these graduates will use these new techniques to increase the basic science knowledge necessary to invent new, extremely high temperature ceramics and composites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：该项目解决了需要一种新的，更有效的方法来阐明和测量在特定温度和组成条件下存在的相或不同形式的氧化物陶瓷中的“相图”的非常高温（HT）图。目前的方法是缓慢的，并且基于在高温下加热陶瓷，冷却它们并在室温（RT）下测量它们。然而，我们不知道在RT观察到的相或形式与HT存在的相或形式相同。在该项目中，开发了新的实验工具，使测量能够在高达3400 ℃的温度下进行，从而提供正确和准确的基础科学知识。这是变革性的理解，这样的陶瓷相图可以方便地确定在很短的时间内。同样的技术可以广泛用于在基础固态物理和化学知识方面取得重大和快速的进展，以便识别下一代复杂的器件材料。在这项研究中培训的本科生和研究生可能随后在飞机设计和制造部门就业，或作为基础科学研究人员，特别是在高强度，同步加速器X射线实验室。还向高中学生和教师开展外联活动。这项研究与确定用于太空探索和下一代电子设备的陶瓷材料有关。技术规格：本研究展示了一种方法，通过该方法，四元钽-氧化钽-钛-钨酸盐（Ta_2 O_5-HfO_2-TiO_2-WO_3）相图可以在原位测量，温度高达3400 ℃，在空气中或在受控气氛下。这项工作结合了实验技术（i）均匀粉末合成的有机空间包埋方法（ii）四极灯炉能够在2000 C的空气和（iii）锥形喷嘴悬浮器能够在3400 C的控制气氛。技术（i）和（ii）是在伊利诺伊大学厄巴纳-尚潘分校发明的，（iii）是由两家小公司开发和改进的。此外，这项研究还产生了理论建模技术，以探索晶体结构之间的取向关系的数学晶格对应关系，因为它们随温度（热膨胀，相变，不变反应）以及整个组成范围而变化。这些方法将被应用到组成四元体系的四组分相图。随着正在开发的实验和理论技术的发展，研究生正在接受全面培训，即未来的科学家。反过来，这些毕业生将使用这些新技术来增加必要的基础科学知识，以发明新的、极高温陶瓷和复合材料。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。