多种稀土离子共同掺杂锆酸镧纳米粉体的熔盐法合成及其涂层性能研究

Thermal barrier coatings (TBCs) are the most advanced high temperature protective coatings and widely used for the protection of the hot-section components of turbine engines, for their good performance at thermal barrier and oxidation resistance. With the improvement of working temperature and thermal efficiency of gas turbine, there is a growing demand for a better performance of the ceramic top-coatings in the thermal barrier coatings (TBCs) whereas conventional yttria-stabilized zirconia (YSZ) ceramics can not meet the demand any more, and the search for new candidate materials that can work at even higher temperature has been intensified in the future. We make the La2Zr2O7(LZ)with high using temperature, good phase stability and lower thermal conductivity as the research object in this project, prepare nano-LZ doped by a multifarious of rare earth, and investigate the influences of dopted rare earth ions on the performance of LZ coating. The detailed content includes: try to optimize the system of molten salts; research mechanism of synthesize process of LZ by molten salts; the prepare the nano-LZ doped by a multifarious of rare earth; prepare the coatings by Air Plasma Spray technology; establish the model of the influence on the LZ doped by rare earth through the research of thermal conductivity and thermal expansion coefficient. The project intends to establish the theoretical and technical basis for the molten salt synthesis mechanism of rare earth oxides and the development of new high-temperature thermal barrier coating materials through the preparation of nano-LZ doped by a multifarious of rare earth ions.

热障涂层兼有隔热和抗氧化功能，是目前最为先进的高温合金表面防护涂层技术，广泛用于保护航空发动机高温部件。近年来，特别是随着飞机发动机向着高温高效方向的发展，Y2O3稳定ZrO2(YSZ)材料已经很难满足高性能需求，研究能替代YSZ用在更高温度下的热障涂层材料成为国内外研究的重点。本项目拟以具有使用温度高、高温下相稳定好、热导率低的La2Zr2O7(LZ)陶瓷材料为研究对象，利用熔盐法制备多种稀土掺杂的纳米LZ粉体材料，研究稀土离子掺杂对LZ涂层性能的影响。具体内容包括：对熔盐体系进行优化；研究LZ陶瓷材料的熔盐合成机理；利用熔盐法合成多种稀土离子掺杂LZ纳米粉体；利用等离子喷涂技术制备涂层；通过对涂层热导率、热膨胀系数等性能的研究，建立稀土掺杂对LZ性能影响的模型，为熔盐法合成稀土氧化物机理的研究及新型高温热障涂层材料的研制奠定理论和技术基础。

近年来,随着航空发动机向高推重比、高流量比、高涡轮进口温度的方向发展,发动机高温部件必须承受更高的温度,从而对热障涂层陶瓷材料提出了新的要求。目前广泛应用的表层陶瓷材料为6%～8%(wt)Y2O3部分稳定的ZrO2(YSZ)，已难以满足涡轮进口温度进一步升高的需要。.本项目利用熔盐法制备了多种稀土掺杂的纳米锆酸镧基（La2Zr2O7，LZ）粉体材料。研究了反应时间、反应温度、及熔盐量对粉体物相等的影响，研究了稀土掺杂（Dy及Gd等）对LZ涂层性能的影响。通过研究发现离子掺杂可以提高LZ涂层的热膨胀系数，明显降低涂层的热导率（在室温到1300℃范围内，LZ涂层的热导率为0.7525 to 3.6094Wm-1K-1，La1.7Dy0.3ZrO7（LDZ）涂层的热导率为0.3559 to 0.9719 Wm-1K-1）。在1300～1500℃的氧煤油超音速火焰烧蚀时可以有效保护高温合金基体，与YSZ相比具有更优良的隔热性能（1300℃、1500℃时，0.5mm厚LDZ涂层隔热性能分别为475℃、357℃）。本项目的完成为LZ基粉体材料制备提供了理论技术支持，同时为未来航空发动机提供了可供选择的热障涂层材料。