GOALI: A Fundamental Investigation of the Design, Processing and Evaluation of a Model, Oxidation Resistant, Functionally-Graded Coating System for Refractory Metals

该研究计划研究包含非晶扩散阻挡层的功能梯度涂层系统。过去的研究已经确定了一种功能梯度的钼硅基涂层体系（MoSi2-SiC），该体系采用物理气相沉积方法沉积在难熔金属衬底上，是一种很有前途的工艺路线。随后可以使用等离子喷涂将足够厚的MoSi2外层应用于功能梯度层。早期的研究还确定了与单质靶（如Mo， Si和C）相比，利用MoSi2-SiC复合靶的潜力。然而，必须在MoSi2-SiC功能梯度涂层和难熔金属衬底之间确定合适的扩散阻挡层，以尽量减少硅和碳向难熔（Mo或W）衬底的扩散。如果不使用这种屏障，则在涂层-基体界面处产生难熔金属的亚硅化物和碳化物，导致涂层系统的抗氧化性和机械性能恶化，并降低涂层寿命。Mo-Si-N-C扩散势垒最近被发现在1260C下仍保持无定形。MoSi2-SiC功能梯度涂层体系在使用温度和室温之间的热循环会在涂层体系中产生应力。因此，有限元建模将用于预测优化的成分梯度和涂层结构，即基材-屏障层-功能梯度层-外层厚的动力层，符合最小化产生的应力，并在空气中长时间保持高达1600C的抗氧化性。？ 工业顾问是梅尔·杰克逊（通用电气公司研发）和威廉·艾伦（UTRC - East Hartford）。这些公司对涡轮发动机材料的高温材料和涂层感兴趣。学生们花时间在工业实验室研究设施中，并在CSM中心会议上展示他们的研究活动。这是一个很好的机会，让学生参与到美国一流的工业材料实验室。MPS OMA办公室正在共同支持这一目标活动。GOALI研究计划的主要目标是探索适用于高温、氧化环境的难熔金属的抗氧化涂层系统。该涂层采用有限元建模设计，并采用新型MoSi2-SiC或MoSi2-Si3N4复合靶材进行物理气相沉积。该研究项目由科罗拉多矿业学院的先进涂层和表面工程实验室（ACSEL）管理，ACSEL是一个工业-大学联盟。＊＊＊

9730775 Moore The research program investigates functionally-graded coating systems that incorporate an amorphous diffusion barrier layer. Past research identified a functionally- graded molybdenum-silicon based coating system (MoSi2-SiC), deposited on the refractory metal substrate using physical vapor deposition as a promising processing route. A sufficiently thick, outer layer of MoSi2 can be subsequently applied to the functionally-graded layer using plasma spraying. The earlier research also identified the potential of utilizing MoSi2-SiC composite targets as compared with elemental targets (e.g. Mo, Si, and C). However, a suitable diffusion barrier layer between the MoSi2-SiC functionally-graded coating and the refractory metal substrate must be identified in order to minimize diffusion of silicon and carbon into the refractory (Mo or W) substrate. If this barrier is not used, sub-silicides and carbides of the refractory metals are produced at the coating-substrate interface, resulting in deterioration of oxidation resistance and mechanical properties of the coating system, as well as a reduction in the coating life. A Mo-Si-N-C diffusion barrier has recently been identified that remains amorphous up to 1260C. Thermal cycling of the MoSi2-SiC functionally-graded coating system between the service temperature and room temperature can produce stresses in the coating system. Therefore, finite element modeling will be used to predict the optimized compositional gradient, and coating architecture, i.e. substrate-barrier layer-functionally-graded layer-outer thick kinetic layer, consistent with minimizing the stresses generated, and maintaining oxidation resistance for prolonged times up to 1600C in air. ? Industrial advisors are Mel Jackson (GE Corp. Research and Development) and William Allen (UTRC - East Hartford). These co mpanies have interest in high temperature materials and coatings for materials used in turbine engines. Students spend time in the industrial laboratory research facilities and present their research activities at CSM Center meetings. It is an excellent opportunity for the students to participate in superb industrial materials laboratories in the United States. The MPS OMA Office is co-supporting this GOALI activity. %%% The main objective of this GOALI research program is to explore oxidation-resistant coating systems for refractory metals for application in high temperature, oxidizing environments. The coatings are designed using finite element modeling and deposited by physical vapor deposition using novel MoSi2-SiC or MoSi2-Si3N4 composite targets. The research program is managed in the Advanced Coatings and Surface Engineering Laboratory (ACSEL), an industry- university consortium, at Colorado School of Mines. ***