CAREER: New Solid State Metal Foams Using Oxide Reduction and Intraparticle Expansion

事业：利用氧化物还原和颗粒内膨胀的新型固态金属泡沫

• 批准号: 2035473
• 负责人: Mark Atwater
• 金额: $ 20.42万
• 依托单位: Liberty University, Inc.
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-15 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2035473&HistoricalAwards=false
• 关键词: CAREER; New; Solid; State; Metal

Nontechnical DescriptionMetals are useful materials, as they are durable and easy to manufacture, but they have characteristically high densities which make them inefficient in many weight-sensitive applications. Their density can be reduced by introducing porosity, but porosity is also useful for increasing surface area, enhancing energy absorption, assisting bone ingrowth and more. Methods used to "foam" metals often require high temperatures, high pressures and/or complex processes, which limit the availability and cost-effectiveness of these materials. A new method has been developed to enhance porosity in metals at modest temperatures using simple, well-established powder metallurgy processes. The fundamental difference is that pores are developed within individual powder particles in the solid state, and this expandable metal powder can be incorporated into current, state-of-the-art foaming processes to enhance the level of porosity, or it can be used as a stand-alone process. This unique approach to creating porous metals may allow for cost reduction, the development of new metals and alloys for solid state foaming and the overall improvement of solid state foam processing. Both the fundamental mechanisms and commercial potential of this technology will be investigated to create a holistic understanding of the process and resulting materials. This technology can result in more fuel-efficient transit, safer vehicles, reduced emissions and much more. Through this work, educational awareness and career opportunities will be developed in partnership with the local community. This will involve establishing, promoting and expanding undergraduate research initiatives and promoting diversity in materials research and nanoscale technologies. Technical DescriptionA new method in the solid state foaming of metals has been developed using standard powder metallurgy processing. The technique involves two steps: (1) disperse oxides in a metal powder and (2) reduce oxides at a temperature sufficient to allow expansion. In general, mechanical milling can be used to create an oxide dispersion-strengthened (ODS) metal which is later foamed under hydrogen at elevated temperature via the formation of steam at oxide sites. The conditions under which this process is achieved depend on the oxide and matrix composition but are expected to be modest when compared to current foaming processes. This fundamentally different approach will allow for advances on three major fronts: (1) the ability to make metal foams with new compositions, (2) enhanced ability to control the structure and properties of the metal foam, and (3) the ability to combine this process with established powder metallurgy foaming methods to significantly increase the resulting porosity.This work will help to elucidate the fundamental mechanisms of this new method and has the potential to alleviate some of the critical issues plaguing solid state foaming. These issues include the complexity of processing, the lack of diversity in foamed metals and alloys and the modest porosities and/or mechanical properties achieved using current solid-state foaming methods. A number of fundamental research questions will be addressed, including: What is the influence of process variables, including reduction temperature, oxide chemistry, content and character, the microstructural properties of the matrix, and quantity and chemistry of process gas(es) on the pore formation process? What is the reduction and pore expansion behavior of multi-element systems, especially in which the elements possess greatly differing oxidation potentials? And what is the fundamental behavior of the ODS powder feedstock during bulk processing? A process map will be produced for creating metallic foams of a given porosity while independently controlling pore size, morphology and interconnectedness.This work will be conducted in a multi-scale manner, and an understanding of the nano- and micro-scale phenomena will be leveraged to inform processing decisions and methods by which to incorporate this feedstock into current, state-of-the-art methodologies. Educational initiatives will impact the university and community through increased collaboration internally and engaging local organizations to provide new opportunities for students to develop professionally. Expanded programs and opportunities in undergraduate research will be developed through this work, and outreach in the community will be conducted to help inform others of advanced materials and manufacturing as well as to inspire the future generation toward science and engineering.

非技术描述类是有用的材料，因为它们耐用且易于制造，但是它们具有特征性的高密度，这使得它们在许多重量敏感的应用中效率低下。可以通过引入孔隙率来降低它们的密度，但孔隙率也可用于增加表面积，增强能量吸收，有助于骨向内生长等。用于“泡沫”金属的方法通常需要高温，高压和/或复杂的过程，从而限制了这些材料的可用性和成本效益。已经开发了一种新的方法，可以使用简单的粉末冶金工艺在适度的温度下增强金属的孔隙率。基本区别在于，孔是在固态的单个粉末颗粒中开发的，并且可以将可扩展的金属粉末纳入当前的最先进的泡沫过程中以提高孔隙率，或者可以用作独立过程。这种创建多孔金属的独特方法可以降低成本，开发新的金属和合金用于固态泡沫以及固态泡沫加工的整体改进。将研究该技术的基本机制和商业潜力，以对过程和产生的材料产生整体理解。这项技术可以导致更高的省油运输，更安全的车辆，减少的排放等等。通过这项工作，教育意识和职业机会将与当地社区合作发展。这将涉及建立，促进和扩大本科研究计划，并促进材料研究和纳米级技术的多样性。技术描述是使用标准粉末冶金加工开发了金属固态泡沫的新方法。该技术涉及两个步骤：（1）将氧化物分散在金属粉末中，（2）在足够膨胀的温度下降低氧化物。通常，机械铣削可用于创建氧化物分散剂的加长（ODS）金属，后来通过氧化物位点的蒸汽形成在升高温度下在氢下进行泡沫。实现此过程的条件取决于氧化物和基质组成，但与当前的泡沫过程相比，预计将是适度的。这种从根本上不同的方法将允许在三个主要方面进步：（1）能够使金属泡沫与新成分制成金属泡沫的能力，（2）增强了控制金属泡沫的结构和特性的能力，以及（3）将这一过程相结合的能力，可以将既有粉末冶金泡沫的方法与较大的孔子相结合的能力。困扰固态起泡的一些关键问题。这些问题包括加工的复杂性，泡沫金属和合金的多样性以及使用当前固态泡沫方法实现的适度孔隙性和/或机械性能。将解决许多基本的研究问题，包括：过程变量的影响，包括降低温度，氧化物化学，内容和特征，矩阵的微结构特性，以及工艺气体（ES）对孔形成过程的数量和化学性能？多元素系统的还原和孔扩展行为是什么，尤其是其中的元素具有巨大的氧化潜力？ ODS粉末原料在批量处理过程中的基本行为是什么？将制作一个过程图，用于创建特定孔隙度的金属泡沫，同时独立控制孔径，形态和相互联系。这项工作将以多规模的方式进行，并了解纳米和微尺度现象的理解，将利用该方法来为当前的方法融入该方法。教育计划将通过内部增加协作并吸引当地组织为学生提供专业发展的新机会来影响大学和社区。将通过这项工作开发扩大的课程和本科研究的机会，并将在社区中进行外展活动，以帮助其他人告知其他人高级材料和制造业，并激发未来的一代迈向科学和工程学。