STTR Phase II: Corrosion Inhibition of Stainless Steel Alloys in High Temperature Chloride Salts for Concentrated Solar Power Applications

在本研究的第一阶段中，开发了一种添加剂，该添加剂可在700℃的温度下在316/316L不锈钢表面形成一层粘结的陶瓷氧化物涂层，当添加到特定的氯盐混合物中时，可起到缓蚀作用。缓蚀剂组合策略的使用将使CSP工厂能够使用经济的不锈钢合金，并将降低基础设施成本。这些解决方案将对可再生能源市场产生直接影响，这将有助于将热太阳能的能源化成本(LCOE)从目前的12？/千瓦时降低到2030年前的3？/千瓦时的目标。从该项目中获得的科学和技术见解可以有益于许多其他应用，如熔融碳酸盐燃料电池、热能存储系统、核熔融氟化物/氯化物反应堆以及其他易受侵蚀性腐蚀的高温系统。在CSP工厂中加入被禁止的熔融氯盐还将提供可持续的绿色能源，减少用水量，创造更多就业机会，并为美国提供能源独立和安全。在社会层面上，基于这项工作所体现的研究主题的教育活动的持续实施和发展将产生影响。这项计划的核心创新是开发一种化学混合物，一种添加剂组合，它可以最大限度地减少700℃下熔融的氯盐对不锈钢的腐蚀。添加剂组合与不锈钢发生反应，在工作温度700℃加入熔融的氯化物中，原位形成缓蚀陶瓷氧化物涂层。氯盐被建议作为第三代CSP工厂的换热流体。在这项拟议的研究中，将严格评估缓蚀剂包策略在现实世界CSP工厂中的可行性。为了模拟CSP工厂的流动条件，将设计和建造一个原型实验室规模的熔体试验回路。在动态条件下，研究长期暴露在高温熔盐中对母材力学性能的影响，同时注意高温下熔盐引起的强度和韧性的退化。还将研究缓蚀剂包对盐的降解行为。将进行更多的研究，以获得关于陶瓷氧化物涂层的成核和生长及其在动态流动条件下的热稳定性和机械稳定性的基本见解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This STTR Phase II project will focus on the development of cost effective, high temperature molten salt heat transfer fluids for third generation concentrated solar power (CSP) plants with operating temperatures 700?C. In the Phase I of this research, an additive package was developed that formed an adherent ceramic oxide coating on 316/316L stainless steel at the temperatures 700?C when added to specific chloride salt blends and inhibit corrosion. The utilization of the inhibitor package strategy will enable the utilization of economical stainless-steel alloys in the CSP plants and would reduce the infra-structure cost. Such solutions will have a direct impact on the renewable energy market which would help to lower the Levelized Cost of Energy (LCOE) for thermal solar from the current cost of 12?/kwh to the target 3?/kwh by 2030. The scientific and technological insight gained in this project could be beneficial to many other applications, such as molten carbonate fuel cells, thermal energy storage systems, nuclear molten fluoride/chloride reactors, and other high-temperature systems that are susceptible to aggressive corrosion. Incorporation of the inhibited molten chloride salt in the CSP plants will also provide sustainable green energy, reduce water usage, create more jobs and offer U.S. energy independence and security. On a societal level, impact will be achieved by the continued delivery and development of educational activities based on the research topics embodied by this work.The core innovation in this proposed program is the development of a chemical mixture, an additive package that would minimize the corrosion of stainless steel induced by molten chloride salts at temperatures 700?C. The additive package reacts with the stainless steel and forms a corrosion inhibiting ceramic oxide coating in-situ when added to the molten chlorides at operating temperatures700?C. The chloride salts are proposed to be the heat transfer fluids for third generation CSP plants. The feasibility of the inhibitor package strategy in a real world CSP plant will be critically assessed in this proposed research. A prototype bench scale molten test loop will be designed and built to mimic the flow conditions in a CSP plant. The effect of prolonged exposure to high temperature molten salts on the mechanical properties of the base metal under dynamic conditions will be studied with attention to the molten salt induced degradation of strength and toughness at elevated temperatures. The degradation behavior of the salt with the inhibitor package will be studied as well. Additional research will be performed to gain fundamental insight on the nucleation and growth of the ceramic oxide coating and its thermal and mechanical stability in dynamic flow conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.