Mechanisms of Toughening Structural Ceramics by Thermal Engineered Laser Shock Peening

热工程激光冲击强化结构陶瓷的机理

• 批准号: 1563145
• 负责人: Bai Cui
• 金额: $ 34.83万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1563145&HistoricalAwards=false
• 关键词: Mechanisms; Toughening; Structural; Ceramics; Thermal

With their combination of heat resistance, wear and corrosion resistance, and high compressive strength, structural ceramics are ideal candidates for many critical aeronautic, automobile, refractory, and nuclear applications. However, the fracture toughness of ceramics is very low compared to metals, which reduces the mechanical reliability. The inability to toughen ceramics has limited their use in critical engineering applications. This award supports research which aims to address this critical gap in knowledge by applying to ceramics a laser processing technique originally devised for metals, to improve the low fracture toughness and crack sensitivity. This research has the potential to lead to the widespread use structural ceramics in a variety of applications such as cutting tools, turbine engines, and armor. The research team will promote engineering education through outreach programs such as "Sunday with a Scientist" presentations at the University of Nebraska State Museum, and the partnership with the McNair Scholars Program to train undergraduate researchers from underrepresented groups. The goal of this research is to improve the low fracture toughness and crack sensitivity of structural ceramics by inhibiting surface-originated crack propagation using a thermally engineered laser shock peening process. To fulfill the research goal, four objectives will be completed to (1) develop the process for performing thermally engineered laser shock peening on ceramics; (2) assess the residual stresses and mechanical properties of ceramics following laser shock peening; (3) reveal the microstructure-property relationship of ceramics in the laser shock peening process; and (4) identify the mechanisms by which laser shock peening toughens ceramics. The team will apply this process to a variety of structural ceramics and measure their residual stresses and fracture toughness. The microstructural evolution of the ceramics will then be characterized using transmission electron microscopy and focused ion beam techniques. The toughening mechanisms will be identified through modeling and ex-situ and in-situ electron microscopy methods. This work will provide new fundamental knowledge of the processing-microstructure-property relationships in ceramics with respect to the laser shock peening process. In addition, the results will advance the field by shedding light on the mechanism of toughening ceramics by controlling the residual stress state and microstructural changes.

结构陶瓷兼具耐热性、耐磨性、耐腐蚀性和高抗压强度，是许多关键航空、汽车、耐火材料和核应用的理想选择。然而，与金属相比，陶瓷的断裂韧性非常低，这降低了机械可靠性。陶瓷不能增韧限制了它们在关键工程应用中的使用。该奖项支持旨在通过将最初为金属设计的激光加工技术应用于陶瓷来解决这一关键知识缺口的研究，以改善低断裂韧性和裂纹敏感性。这项研究有可能导致广泛使用的结构陶瓷在各种应用，如切削工具，涡轮机发动机，装甲。该研究小组将通过推广计划促进工程教育，例如在内布拉斯加州立大学博物馆举办的“星期天与科学家”演讲，以及与麦克奈尔学者计划合作，培训来自代表性不足群体的本科研究人员。本研究的目的是改善低断裂韧性和裂纹敏感性的结构陶瓷，通过抑制表面起源的裂纹扩展，使用热工程激光冲击喷丸工艺。为实现这一研究目标，本论文将完成以下四个方面的工作：（1）研究陶瓷材料的热工程激光冲击强化工艺，（2）研究陶瓷材料激光冲击强化后的残余应力和力学性能，（3）揭示陶瓷材料激光冲击强化过程中的组织-性能关系，（4）研究陶瓷材料的热工程激光冲击强化工艺。激光冲击强化增韧陶瓷的机理。该团队将把这一过程应用于各种结构陶瓷，并测量它们的残余应力和断裂韧性。陶瓷的微观结构的演变，然后将其特征在于使用透射电子显微镜和聚焦离子束技术。增韧机制将通过建模和非原位和原位电子显微镜方法来确定。这项工作将提供新的基础知识的加工-显微组织-性能关系的陶瓷激光冲击喷丸工艺。此外，通过控制残余应力状态和微观结构的变化，揭示了陶瓷增韧的机理，从而推动了该领域的发展。