Hard Coatings: Toughness Enhancement through Responsive Phase Change

硬质涂层：通过响应相变增强韧性

• 批准号: 1537984
• 负责人: Daniel Gall
• 金额: $ 32.53万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1537984&HistoricalAwards=false
• 关键词: Hard; Coatings; Toughness; Enhancement; through

Hard coatings are used in a wide range of industries and prolong the life and increase the performance of components that experience sliding contact. Coatings on cutting tools represent an annual world market of $20-70 billion, and are essential for manufacturing in aerospace, automotive, and energy industries. Research over the last two decades has resulted in a considerable increase in the hardness of these coatings. However, despite these improvements, a major shortcoming of these ceramic coatings remains: they are brittle, leading to crack formation and premature failure in many applications. This award supports fundamental research in materials science and engineering to address this shortcoming. New coating materials are explored which are not only hard, but also tough. The new coating materials are designed such that atoms rearrange when exposed to large loads. This process stops small cracks from growing into large cracks, which can prevent failure in current hard coating materials, and in turn, failure of the component. This research has the potential to transform industrial coating materials design and facilitate the development of wear-resistant hard coatings for emerging applications ranging from environment-friendly lubricant-free cutting tools to high-performance bearings for fuel-efficient jet engines and high-temperature turbines for gas, wind, or concentrating solar power plants.This integrated experimental and theoretical research effort will explore phase-change toughening mechanisms for hard coating materials. The key idea is to create a materials system where the stress concentration near crack tips induces a transformation from a metastable cubic to a stable hexagonal phase, facilitating plasticity and/or local expansion which, in turn, suppresses crack propagation and results in a dramatic increase in the fracture toughness. The research explores if the ductility (and therefore the toughness) in wear-resistant nitrides and carbides can be increased through stress-induced phase change, without sacrificing their hardness. Such transformation toughening is well known for bulk ceramic materials like zirconia and, if successfully applied to coating materials, has the potential to dramatically increase the wear-resistance of protective coatings. The study involves (i) first-principles calculations to predict most promising compositions, (ii) coating synthesis by reactive sputtering including control of microstructure through ion-irradiation, epitaxial constraints, and temperature, (iii) high pressure phase transition studies using a diamond anvil cell, and (iv) materials characterization by nanoindentation to demonstrate enhanced toughness.

硬质涂层广泛应用于各个行业，可延长滑动接触部件的使用寿命并提高其性能。切削工具涂层每年的全球市场价值为 20-700 亿美元，对于航空航天、汽车和能源行业的制造至关重要。过去二十年的研究已经使这些涂层的硬度显着增加。然而，尽管有这些改进，这些陶瓷涂层的一个主要缺点仍然存在：它们很脆，导致在许多应用中形成裂纹和过早失效。该奖项支持材料科学和工程的基础研究，以解决这一缺陷。探索出不仅坚硬而且坚韧的新型涂层材料。新涂层材料的设计使得原子在受到大负载时会重新排列。该过程可以阻止小裂纹发展成大裂纹，从而防止当前硬涂层材料失效，进而防止部件失效。这项研究有可能改变工业涂层材料的设计，并促进耐磨硬涂层的开发，其应用范围从环保型免润滑切削工具到节能喷气发动机的高性能轴承以及燃气、风能或聚光太阳能发电厂的高温涡轮机。这项综合实验和理论研究工作将探索硬涂层材料的相变增韧机制。其关键思想是创建一种材料系统，其中裂纹尖端附近的应力集中会导致从亚稳立方相转变为稳定的六方相，从而促进塑性和/或局部膨胀，从而抑制裂纹扩展并导致断裂韧性显着增加。该研究探讨了是否可以通过应力引起的相变来提高耐磨氮化物和碳化物的延展性（以及韧性），而不牺牲其硬度。这种相变增韧对于氧化锆等块状陶瓷材料来说是众所周知的，如果成功应用于涂层材料，则有可能显着提高保护涂层的耐磨性。该研究涉及（i）第一性原理计算以预测最有前途的成分，（ii）通过反应溅射合成涂层，包括通过离子辐照、外延约束和温度控制微观结构，（iii）使用金刚石砧室进行高压相变研究，以及（iv）通过纳米压痕进行材料表征以证明增强的韧性。

项目成果

Conductive surface oxide on CrN(001) layers

• DOI: 10.1063/1.5091034
• 发表时间: 2019-04
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Mary E. McGahay;D. Gall

Energetics of point defects in rocksalt structure transition metal nitrides: Thermodynamic reasons for deviations from stoichiometry

• DOI: 10.1016/j.actamat.2018.07.074
• 发表时间: 2018-10-15
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: Balasubramanian, Karthik;Khare, Sanjay, V;Gall, Daniel
• 通讯作者: Gall, Daniel

Valence electron concentration as an indicator for mechanical properties in rocksalt structure nitrides, carbides and carbonitrides

• DOI: 10.1016/j.actamat.2018.04.033
• 发表时间: 2018-06-15
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: Balasubramanian, Karthik;Khare, Sanjay V.;Gall, Daniel
• 通讯作者: Gall, Daniel