铝硅涂层在不同温度下的超高温热腐蚀行为及其改性基础

发布时间：2018-04-30 07:56

本文选题：热障涂层 + 金属粘结层　；参考：《江苏大学》2017年硕士论文

【摘要】：燃气涡轮发动机是体现国家核心竞争力的重要标志,涡轮进口温度是先进燃气涡轮发动机的一大特征,国际上公认热障涂层是显著提高发动机服役温度最切实可行的办法。金属粘结层在极高服役温度下的抗氧化腐蚀能力,尤其是其抗热腐蚀性(即含盐条件下的热氧化)直接关系到热障涂层的使用寿命。本文围绕“热障涂层抗超高温氧化腐蚀金属粘结层”这一研究主题,以具有较好抗高温热腐蚀性能且极易形成在超过1000℃以上仍具有良好稳定性氧化铝膜的铝硅涂层为对象,研究了其在1050℃、1150℃、1250℃混合硫酸盐中热腐蚀后的微观形貌、热腐蚀动力学、腐蚀产物等热腐蚀行为,并初步探讨了铝硅涂层在超高温环境下的热腐蚀机理;同时,考察了预氧化处理对改善铝硅涂层抗超高温热腐蚀性能的效果;从而为新型抗超高温氧化腐蚀金属粘结层的研制提供一定的理论基础和技术支持。所开展的研究工作和取得的成果如下:(1)研究了铝硅涂层在1050℃温度下混合硫酸盐中热腐蚀行为。研究表明:相对于高温条件,铝硅涂层在1050℃下混合硫酸盐中的热腐蚀要严重得多。铝硅涂层热腐蚀70小时后开始失重,此时表面疏松的氧化膜不再具有保护作用,不仅涂层中Al和Ni直接与熔盐相互作用,而且涂层中的Cr、Si也直接参与了与熔盐的反应,同时高温合金基体中的Ti也已扩散至表面。在热腐蚀90小时后其腐蚀层的深度已达约75μm。(2)研究了铝硅涂层在1150℃温度下混合硫酸盐中热腐蚀行为,并初步讨论了其热腐蚀机制。研究表明:铝硅涂层在1150℃下混合硫酸盐中发生了灾难性的热腐蚀,热腐蚀过程中Si元素呈向外扩散趋势,70h后,涂层中几乎不含Si元素。热腐蚀70h后占涂层50%左右的腐蚀区域已经完全剥落。并且热腐蚀70h后残留区域的扩散障在此温度下能够有效的抵御硫酸盐的侵蚀,对基体起到了一定的保护作用。(3)研究了铝硅涂层在1250℃温度下混合硫酸盐中热腐蚀行为。研究表明:在热腐蚀达到60h时,腐蚀产物完全剥落,涂层仅剩下原有的50%左右,热腐蚀80h已经失重达到15.85mg/cm2,涂层已经完全剥落,并且内层扩散障无法在1250℃下混合硫酸盐的环境中长时间的抑制熔盐的侵蚀,扩散障内部出现裂纹并且迅速的剥落,基体遭受了毁灭的破坏。(4)以铝硅涂层为对象,在其表面预制了一层约8微米厚的保护性氧化膜,考察了其在1150℃下混合硫酸盐中的热腐蚀行为,并初步讨论了其热腐蚀机制。研究表明:预氧化铝硅涂层在1150℃下混合硫酸盐中热腐蚀的前60h,其表面形成以氧化铝为主的连续致密的保护性氧化膜,而且其热腐蚀动力学曲线呈现近似抛物线规律,热腐蚀150h后,铝硅涂层特有的内层扩散障表现出较好的抑制O、S等元素继续侵入的作用。综上所述,铝硅涂层在超过1000℃混合硫酸盐中遭受了较为严重的热腐蚀,而预氧化对改善其抗超高温热腐蚀性能有一定的作用;本文研究结果进一步证实了在开展抗超高温氧化腐蚀金属粘结层的研究的研究过程中,需更积极地关注其超高温热腐蚀行为及机理的研究。
[Abstract]:Gas turbine engine is an important symbol to embody the core competitiveness of the country. The inlet temperature of the turbine is a major feature of the advanced gas turbine engine. It is recognized that the thermal barrier coating is the most practical way to improve the service temperature of the engine in the world. Thermal corrosion (i.e., thermal oxidation under salt conditions) is directly related to the service life of the thermal barrier coating. This paper focuses on the research topic of "thermal barrier coating anti ultrahigh temperature oxidation corrosion metal bonding layer", with a good resistance to high temperature and hot corrosion, and the aluminum silicon coating with good stability of alumina film is easily formed at more than 1000 degrees. The microstructure, thermal corrosion kinetics, corrosion products and other thermal corrosion behaviors of the mixed sulphate at 1050, 1150 and 1250 C were investigated, and the thermal corrosion mechanism of Al Si coating in ultra high temperature environment was preliminarily discussed. At the same time, the thermal corrosion resistance of Al Si coating to improve the thermal corrosion resistance of Al Si coating was investigated. The research work and achievements are as follows: (1) the thermal corrosion behavior of Al Si coating at 1050 C is studied. The study shows that the aluminum silicon coating is at 1050 C relative to the high temperature condition. The hot corrosion in the mixed sulfate is much more serious. The thermal corrosion of the aluminum silicon coating begins to lose weight after 70 hours, and the loose oxide film is no longer protective, not only the Al and Ni in the coating interact directly with the molten salt, but also the Cr and Si in the coating are directly involved in the reaction with the molten salt, and the Ti in the superalloy matrix has also been expanded. After 90 hours of hot corrosion, the depth of the corrosion layer has reached about 75 M. (2). The thermal corrosion behavior of Al Si coating at 1150 C was investigated and its thermal corrosion mechanism was preliminarily discussed. The study showed that the aluminum silicon coating produced a catastrophic thermal corrosion in the mixed sulfate at 1150 C, and the Si element in the thermal corrosion process. There is an outward diffusion trend, after 70h, the coating contains almost no Si element. The corrosion area of about 50% of the coating after hot corrosion 70h has been completely peeled. And the diffusion barrier of the residual region after hot corrosion 70h can effectively resist the sulfate erosion at this temperature, and it has a definite protective effect on the matrix. (3) the aluminum silicon coating is studied in 1250. The study shows that the corrosion product is completely exfoliated when the thermal corrosion reaches 60H, only about 50% of the coating is left, the thermal corrosion 80h has been lost to 15.85mg/cm2, the coating has been completely peeled and the internal diffusion barrier can not be fused for a long time in the environment of mixed sulphate at 1250. The corrosion of salt, the cracks in the diffusion barrier and rapid exfoliation, the matrix suffered destruction. (4) a protective oxide film was prefabricated on the surface of aluminum and silicon with a protective oxide film of about 8 microns thick. The thermal corrosion of mixed sulphate at 1150 C was investigated and its thermal corrosion mechanism was preliminarily discussed. The surface of the alumina silicon coating at 1150 C in the mixture of sulphate and hot corrosion on the front 60H formed a continuous and dense protective oxide film on the surface, and its thermal corrosion kinetic curve showed an approximate parabolic law. After hot corrosion 150h, the internal diffusion barrier of the aluminum silicon coating showed a better inhibition of O, and the S and other elements continued to invade. In summary, the aluminum silicon coating has been subjected to more severe thermal corrosion in the mixed sulfate more than 1000 degrees C, and the preoxidation has a certain effect on improving its super high temperature corrosion resistance. Polar focus on its high temperature hot corrosion behavior and mechanism.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

【参考文献】