Development of high-temperature hardness and fracture toughness models for superalloy coatings based on micromechanics theory

基于微观力学理论的高温合金涂层高温硬度和断裂韧性模型建立

• 批准号: RGPIN-2014-04285
• 负责人: Liu, Rong
• 金额: $ 1.97万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=657805
• 关键词: Development; temperature; hardness; fracture; toughness

The term superalloy is used to describe nickel- or cobalt-based alloys that are generally employed when operating temperatures are beyond about 540ºC. These alloys also contain high chromium, moderate tungsten and/or molybdenum, and minor carbon or silicon. Because of their unique chemical compositions and microstructures, these alloys possess excellent wear resistance, mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. In more recent years, with the increasing of operation temperature and wear/corrosion severity for many mechanical components in industrial applications, for example, the hot-section components in gas turbine engines, and the advance of coating deposition technologies, superalloys are more often used as surface coatings for protection of machinery in energy and aerospace industry against wear and corrosion attacks in high-temperature environments. However, due to the limitations of the existing testing facilities and methodologies, the high temperature mechanical properties of these coatings are difficult to assess, and hence have been rarely reported. The lack of these properties has significantly limited the application of these alloys. To this end, the proposed research is aimed to develop the high temperature hardness and fracture toughness models for evaluating or assessing the strength of superalloy coatings based on micromechanics theory. High-temperature microindentation-based approaches will be employed, combined with microfracture mechanics theory, in the model development. The relationship between hardness and fracture toughness will be established to demystify the mechanisms that govern the fracture/failure of superalloy coatings. Furthermore, this research also attempts to contribute to the advance of design and fabrication of superalloy coatings with less trial and-error, thus saving the experimental cost and shortening the design and fabrication cycle. The proposed methods for high temperature hardness determination and fracture toughness assessment of superalloy coatings can be extended to a range of coating systems such as ceramics, metal ceramic composites, etc.

高温合金一词用于描述镍基或钴基合金，这些合金通常在工作温度超过约540℃时使用。这些合金还含有高铬，中等的钨和/或钼，和少量的碳或硅。由于其独特的化学成分和显微组织，这些合金在高温下具有优异的耐磨性，机械强度和抗蠕变性，良好的表面稳定性以及耐腐蚀和抗氧化性。近年来，随着工业应用中许多机械部件（例如燃气涡轮发动机中的热截面部件）的工作温度和磨损/腐蚀严重程度的提高，以及涂层沉积技术的进步，高温合金越来越多地被用作保护能源和航空航天工业机械免受高温环境磨损和腐蚀的表面涂层。然而，由于现有测试设备和方法的限制，这些涂层的高温机械性能难以评估，因此很少有报道。这些性能的缺乏极大地限制了这些合金的应用。为此，本研究旨在建立基于微观力学理论的高温合金涂层强度评价模型和断裂韧性模型。在模型开发中，将采用基于高温微压痕的方法，并结合微断裂力学理论。建立硬度与断裂韧性之间的关系，揭示高温合金涂层断裂失效的机理。此外，本研究还试图通过减少试验和错误来推动高温合金涂层的设计和制造，从而节省实验成本，缩短设计和制造周期。所提出的高温合金涂层的高温硬度测定和断裂韧性评估方法可以推广到陶瓷、金属陶瓷复合材料等涂层体系。