Tuning Nanostructured Morphology in Superhard Metal Borides

调整超硬金属硼化物的纳米结构形态

• 批准号: 2004616
• 负责人: Richard Kaner
• 金额: $ 60万
• 依托单位: University of California-Los Angeles
• 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: 2020-06-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2004616&HistoricalAwards=false
• 关键词: Tuning; Nanostructured; Morphology; Superhard; Metal

NON-TECHNICAL SUMMARY:Mechanical hardness is an important property used to determine the applications of materials in the machining and manufacturing industries. Due to the extensive use of hard materials as cutting tools and abrasives, the demand for superhard materials has been steadily increasing. The best-known superhard material – diamond – is not effective at cutting and drilling steel due to its poor thermal stability in air and its tendency to react with the iron in the steel it is trying to cut. Therefore, there is great interest in finding alternatives to traditional superhard materials. These are needed in the construction, automotive, and other industries to replace costly and low performing traditional hard materials like tungsten carbide. To address these issues, the Principal Investigators (PIs) are designing a new generation of superhard materials that will provide greatly increased hardness and the ability to cut steels and other materials at lower cost. Inspired by the unique properties of natural diamond, the Principal Investigators have focused on creating networks with similar properties in other compounds, focusing on mixtures of electron-rich metals and boron. The novel superhard materials are synthesized at ambient pressure and characterization will be conducted to understand the correlation between material structure and hardness. The educational efforts of the PIs, which address the needs of students ranging from elementary school to college undergraduates, include course development, teacher workshops for elementary, middle, and high schools in the greater Los Angeles area, and school outreach visits. Workforce development occurs through the training of graduate students, who also assist with outreach programs and mentor UCLA undergraduate students through research. This project is supported by the Solid State and Materials Chemistry program within the Division of Materials Research.TECHNICAL SUMMARY:Hardness is a physical phenomenon dependent on both the chemical bond strength and grain structure of a material. An understanding of how to design new superhard materials thus requires sufficient mechanistic insight and control of both bonding and grain morphology. To address this challenge, the Principal Investigators (PIs) are combining the synthesis of a wide range of transition metal boride systems with high-pressure studies to obtain lattice-specific information about plastic deformations in a broad range of bulk and nanoscale materials. These metal boride structures consist of high valence electron density metals, combined with multiple short boron-boron bonds, providing a highly covalent bonding network that is resistant to slip and dislocations, combined with high electrostatic repulsion that resists bond compression. The goal of the proposed work, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, is to synthetically control both grain size and morphology. In bulk materials, this is being accomplished through the decomposition of metastable dodecaboride phases in the WB4 system and through precipitation of secondary phases in the ReB2 system. Additionally, molten salt methods are being used to develop nano grain-sized metal borides such as nano-ReB2 and nano-WB4. These synthetic approaches thus aim to enhance extrinsic hardness in both bulk and nano-sized materials. Materials are being analyzed through Vickers hardness testing and high-pressure experiments in diamond anvil cells. With an understanding of the coupled effects of bonding and grain morphology, the research team aims to systematically tune nanostructured materials and advance the next generation of superhard metal borides. The broader impacts of the work lie in workforce development through the training of graduate students, in the extensive outreach efforts of the PIs, which address the needs of students ranging from elementary school to college undergraduates, and in the significant potential for impact on the commercial cutting, drilling and machining industries.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.

非技术性总结：机械硬度是用于确定材料在机械加工和制造业中的应用的重要特性。由于硬质材料作为切削工具和磨料的广泛使用，对超硬材料的需求一直在稳步增长。最著名的超硬材料-金刚石-由于其在空气中的热稳定性差，并且易于与其试图切割的钢中的铁反应，因此在切割和钻孔钢时无效。因此，人们对寻找传统超硬材料的替代品非常感兴趣。建筑、汽车和其他行业需要这些材料来取代昂贵且性能低下的传统硬质材料，如碳化钨。为了解决这些问题，主要研究人员（PI）正在设计新一代超硬材料，这些材料将大大提高硬度，并能够以较低的成本切割钢材和其他材料。受天然金刚石独特性质的启发，主要研究人员专注于在其他化合物中创建具有类似性质的网络，重点关注富电子金属和硼的混合物。在环境压力下合成新型超硬材料，并进行表征以了解材料结构与硬度之间的相关性。PI的教育工作，解决学生的需求，从小学到大学本科生，包括课程开发，教师研讨会的小学，初中和高中在大洛杉矶地区，和学校外展访问。劳动力发展通过研究生的培训发生，他们还通过研究协助推广计划和指导UCLA的本科生。 该项目由材料研究部的固态和材料化学项目支持。技术概要：硬度是一种物理现象，取决于材料的化学键强度和晶粒结构。因此，理解如何设计新的超硬材料需要足够的机械洞察力和控制键合和晶粒形态。为了应对这一挑战，主要研究人员（PI）正在将各种过渡金属硼化物系统的合成与高压研究相结合，以获得有关各种散装和纳米级材料塑性变形的晶格特定信息。这些金属硼化物结构由高价电子密度金属组成，与多个短硼-硼键结合，提供抗滑移和位错的高度共价键合网络，与抵抗键压缩的高静电排斥结合。拟议工作的目标，由材料研究部内的固态和材料化学计划的支持，是综合控制晶粒尺寸和形态。在散装材料中，这是通过WB 4系统中亚稳十二硼化物相的分解和ReB 2系统中第二相的沉淀来实现的。此外，熔盐方法被用于开发纳米晶粒尺寸的金属硼化物，如纳米ReB 2和纳米WB 4。因此，这些合成方法的目的是提高体材料和纳米材料的外在硬度。通过维氏硬度测试和金刚石压砧单元中的高压实验对材料进行分析。通过了解结合和晶粒形态的耦合效应，研究团队的目标是系统地调整纳米结构材料并推进下一代超硬金属硼化物。这项工作的更广泛影响在于通过培训研究生来发展劳动力，在PI的广泛推广工作中，解决了从小学到大学本科生的学生的需求，以及对商业切割的重大潜在影响，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

项目成果

Enhanced Hardening Effects on Molybdenum-Doped WB 2 and WB 2 –SiC/B 4 C Composites

增强钼掺杂 WB 2 和 WB 2 → SiC/B 4 C 复合材料的硬化效果

• DOI: 10.1021/acs.chemmater.2c00386
• 发表时间: 2022
• 期刊: Chemistry of Materials
• 影响因子: 8.6
• 作者: Pangilinan, Lisa E.;Hu, Shanlin;Turner, Christopher L.;Yan, Jinyuan;Kavner, Abby;Mohammadi, Reza;Tolbert, Sarah H.;Kaner, Richard B.
• 通讯作者: Kaner, Richard B.

Hardening Effects in Superhard Transition-Metal Borides

• DOI: 10.1021/accountsmr.1c00192
• 发表时间: 2021-12-30
• 期刊: ACCOUNTS OF MATERIALS RESEARCH
• 影响因子: 14.6
• 作者: Pangilinan, Lisa E.;Hu, Shanlin;Kaner, Richard B.
• 通讯作者: Kaner, Richard B.

Exploring the hardness and high-pressure behavior of osmium and ruthenium-doped rhenium diboride solid solutions

• DOI: 10.1063/5.0135620
• 发表时间: 2023-03
• 期刊: APL Materials
• 影响因子: 6.1
• 作者: Shanling Hu;Lisa E. Pangilinan;Christopher L. Turner;R. Mohammadi;A. Kavner;R. Kaner;S. Tolbert