搪瓷涂层对高温合金的高温氧化防护机理研究

Enamel coatings have their unique advantages for application as high-temperature protective coatings for superalloys. However, there is little publication concerning deep insight on the protection mechanisms of the enamel coatings all over the world. According to the commonly accepted traditional theory, it follows that the enamel coatings act as an isolator which separate the superalloy substrates from corrosive atmosphere. However, it ignores the influence of interfacial stability of enamel/alloy on the protectiveness of the system. Because the activity of enamel coating enhances at high temperature, it can react with the alloy substrate, which thus leads to degradation of the interface. Additionally, the alloy ions can easily diffuse from the interface of enamel/alloy to the out surface of enamel coating and further react with the environment after interfacial reaction. This process deteriorates the protectiveness of the enamel coatings. In this project, the regulation of interfacial reactions between superalloys and enamel coatings, the montage of interface structure controlling, the transportation properties of alloy ions in enamel coatings, as well as the limiting steps responsible to the high-temperature oxidation process of the enamel coated superalloy systems are systematically studied. Based on these studies, the effect of preparation procedures and the enamel/alloy interfacial structure on the protectiveness of the enamel coatings are acquired, and the protection mechanisms of enamel coatings for superalloy substrates against high-temperature oxidation are illustrated, therewith, which will establish the theoretical foundation for the application of enamel coatings on superalloy substrates.

搪瓷涂层作为高温合金的防护涂层有其独特的优势，但是就搪瓷涂层对高温合金的高温氧化防护机理而言，目前国内外尚未见任何深入研究的报道。传统理论认为搪瓷涂层的高温防护机理主要体现为涂层对外界氧化介质的隔离，忽略了涂层/合金界面稳定性对防护效果的影响。高温下搪瓷活性较高，易于与合金基体发生界面反应，致使两者界面的劣化。另一方面，界面反应后合金离子能够比较容易地由搪瓷/合金界面处扩散至搪瓷涂层的外表面，并进一步与环境发生反应，弱化搪瓷涂层的高温防护效果。本项目拟通过对搪瓷涂层与高温合金的界面反应规律、界面结构调控、金属离子在搪瓷中的传输特性以及搪瓷涂覆高温合金的高温氧化控制步骤的系统研究，探讨搪瓷涂层的制备条件、搪瓷/合金界面结构对搪瓷涂层高温防护性能的影响机制，提出搪瓷涂层对高温合金的高温氧化防护机理，为高温合金用搪瓷涂层的设计提供理论指导。

搪瓷涂层作为高温合金的防护涂层有其独特的优势，但是就搪瓷涂层对高温合金的高温氧化防护机理而言，目前国内外尚未见任何深入研究的报道。传统理论认为搪瓷涂层的高温防护机理主要体现为涂层对外界氧化介质的隔离，忽略了涂层/合金界面稳定性对防护效果的影响。高温下搪瓷活性较高，易于与合金基体发生界面反应，致使两者界面的劣化。另一方面，界面反应后合金离子能够比较容易地由搪瓷/合金界面处扩散至搪瓷涂层的外表面，并进一步与环境发生反应，弱化搪瓷涂层的高温防护效果。通过本项目的研究，揭示了高温合金与传统的高温搪瓷涂层之间界面反应类型、反应特征以及界面反应后界面产物层的生长、演化，确定了界面反应对高温氧化产生影响的内在机制；阐明了高温合金中的主要合金元素在高温搪瓷涂层中的溶解、传输规律，及其对涂层抗高温氧化性能的影响规律；提出了界面结构调控的微观机理并推导出了搪瓷涂层的服役寿命预测公式；最终系统构建了搪瓷涂层对高温合金的高温氧化防护机理，为高温合金用搪瓷涂层的设计提供理论指导。.通过该项目的资助，在搪瓷涂层的高温防护机理研究基础之上，完全掌握了高温合金用搪瓷涂层的成分设计原理，研制了若干种新型高温搪瓷涂层，并通过与东方汽轮机有限公司等企业要求，开发了燃气轮机高温部件防护用搪瓷基复合涂层体系。项目执行四年时间内，发表了SCI收录论文共17篇，申请国家发明专利4项。培养博士生毕业研究生1名，硕士毕业研究生1名，在读博士生1名。