GOALI: Platinum-Enriched Gamma + Gamma Prime Bond Coats for Next-Generation Single-Crystal Superalloys

技术支持：单相β（Ni，Pt）Al涂层是最先进的热障涂层（TBC）系统中公认的工业标准，可保护高温合金免受高温氧化。当应用于具有增加的耐火元素含量的单晶超合金（例如，第三代和潜在的第四代超级合金），这是由于在粘结涂层/超级合金界面附近形成脆性拓扑紧密堆积（TCP）相和形成二次反应区（SRZ）。田纳西理工大学（TTU）和通用电气飞机发动机（GEAE）之间的GOALI合作努力，以及橡树岭国家实验室（ORNL）的额外参与，探索了一种新的粘合涂层系统。与（Ni，Pt）Al粘结涂层相比，新的富含Pt的γ-γ '两相粘结涂层提供了更高的蠕变强度、涂层与高温合金基底之间更好的相容性、改善的冶金稳定性和降低的制造成本的优点。本研究的重点是：（1）通过在成分可控的铸造模型合金上合成γ-γ '涂层，阐明高温合金基体中合金元素对涂层氧化性能的影响;（2）阐明涂层中Pt对高温合金基体中某些难熔元素有害作用的抵消作用;（3）评估这种新的粘结涂层系统的长期稳定性，以解释与基材的相互扩散和微观结构的演变。GEAE将为铸造模型合金和涂层提供总体设计指南，并将提供单晶高温合金材料和TBC涂层。将为GEAE的镍基高温合金确定具有最佳成分和微观结构的定制设计的粘结涂层，重点是新一代单晶。涂层合金的性能将通过TTU和ORNL的实验室氧化试验以及GEAE设施的模拟发动机环境试验进行评估。 非技术性：该研究不仅为下一代单晶高温合金提供了新的粘结层候选材料，而且为未来高温合金和TBC系统的设计提供了依据。该项目允许PI，一个年轻的女教师在TTU，以进一步她在高温涂料领域的研究。GOALI研究的一个重要方面是为本科生和研究生提供在学术/行业团队环境中进行研究的机会。GEAE的短期访问将帮助学生了解材料设计/制造方面的真实的工业挑战，并为未来的职业生涯做好更好的准备。将鼓励女学生参加，并有一名女博士。将招募学生从事这个项目。通过推广计划，“工程未来”，最近由TTU和当地的女工程师协会发起，PI计划通过实践学习研讨会向田纳西州中部的5 - 8年级的女孩介绍材料的奇妙世界，以培养科学好奇心。一个电弧熔炉，将获得进行研究，将是一个及时的补充，在TTU的整体材料研究设施，材料加工已被列为该大学的推力研究领域。该研究将与领先的工业公司和国家实验室建立长期的研究合作，从而提高田纳西州唯一的专业技术大学TTU的研究质量和能力。

TECHNICAL: The single-phase beta (Ni,Pt)Al coating is an accepted industrial standard as the bond coat in state-of-the-art thermal barrier coating (TBC) systems that protect superalloys against high-temperature oxidation. This coating faces challenges when applied to single crystal superalloys with increased content of refractory elements (e.g., the 3rd-generation and potential 4th-generation superalloys) due to formation of brittle topologically close-packed (TCP) phases and formation of a secondary reaction zone (SRZ) near the bond coat/superalloy interface. This GOALI collaborative effort between Tennessee Technological University (TTU) and General Electric Aircraft Engines (GEAE), with additional participation from Oak Ridge National Laboratory (ORNL), explores a new bond coat system. Compared to the (Ni,Pt)Al bond coat, the new Pt-enriched gamma-gamma prime, two-phase bond coat offers the advantages of a higher creep strength, better compatibility between the coating and superalloy substrate, improved metallurgical stability, and reduced manufacturing cost. This research focuses on (1) elucidating the effect of alloying elements in superalloy substrates on coating oxidation performance through synthesis of the gamma-gamma prime coatings on cast model alloys with well-controlled compositions; (2) clarifying the effect of Pt in the coating on counteracting detrimental effects of some refractory elements from the superalloy substrate; (3) assessing the long-term stability of this new bond coat system to account for interdiffusion with the substrate and evolution of the microstructure. GEAE will provide overall design guidelines for both cast model alloys and coatings and will supply single-crystal superalloy materials and TBC coatings. Custom-designed bond coats with optimal composition and microstructure will be identified for GEAE's Ni-base superalloys with the emphasis on newer-generation single crystals. The performance of the coated alloys will be evaluated by laboratory oxidation tests at TTU and ORNL, as well as tests in simulated engine environments at GEAE's facilities. NONTECHNICAL: This research will not only offer new bond coat candidates for the next-generation single-crystal superalloys but also provide a basis for the design of future superalloys and TBC systems. The project allows the PI, a young female faculty member at TTU, to further her research in the field of high-temperature coatings. An important aspect of this GOALI research is to provide the opportunity for undergraduate and graduate students to perform research in an academic/industry team environment. Short-term visits at GEAE will help students appreciate real industrial challenges in materials design/fabrication and better prepare them for future careers. Female students will be encouraged to participate and one female Ph.D. student will be recruited to work on the project. Through an outreach program, "Engineering a Future", recently initiated by TTU and the local Society of Women Engineers, the PI plans to introduce the wonderful world of materials to the girls in 5th-8th grades across the Mid-Tennessee via a hands-on learning workshop to foster scientific curiosity. An arc melter, to be acquired for conducting the research, will be a timely addition to the overall materials research facility at TTU, as materials processing has been listed as a thrust research area of the university. The research will build long-term research collaborations with leading industrial companies and national laboratories, thus enhancing the research quality and capability of TTU, the only dedicated technological university in the State of Tennessee.