纳米热障涂层材料Ln_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)(Ln=La,Nd,Sm,Gd)的热物性能

Thermophysical Properties of Ln_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)(Ln=La,Nd,Sm,Gd)Nanomaterials for Thermal Barrier Coatings

用水热合成法制备纳米热障涂层材料Ln_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)(Ln=La,Nd,Sm,Gd),表征其晶体结构、形貌、晶格参数、平均粒径尺寸和比表面积并研究了相关的热物性能及其机理。对XRD谱和Raman谱的分析表明,La_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)、Nd_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)和Sm_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)均为烧绿石结构,而Gd_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)为萤石结构。结合SEM观察、体积收缩以及相对密度,分析了块材的抗烧结性能。系统对比研究了晶体生长行为、热膨胀系数和热导率等热物性能。结果表明:随着Ln离子半径的减小(La>Nd>Sm>Gd)Ln_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)(Ln=La,Nd,Sm,Gd)纳米材料的晶体生长活化能和热膨胀系数均呈增大的趋势,而热导率则呈降低的趋势。

Thermal barrier coatings are widely used in the protection of engine turbine blade,in this paper,Ln_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)(Ln=La,Nd,Sm,Gd)nanomaterials for the applications of thermal barrier coatings were synthesized by hydrothermal method,the crystallographic structures,morphologies and related thermophysical properties of powders and their bulk materials were comparatively assessed via various techniques.The analysis results of XRD and Raman spectra indicate that La_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7),Nd_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)and Sm_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)are pyrochlore structures,while Gd_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)belongs to fluorite type.The lattice parameters,average particle sizes and specific surface areas were also characterized.The volume shrinkage/relative density,the sintering-resistance properties of the four bulk materials were evaluated by SEM observation.Additionally,their thermophysical properties(such as the activation energy of crystal growth,thermal expansion coefficient,and thermal conductivity)were investigated in detail.As the ionic radii of Ln decreasing,the activation energy of crystal growth and thermal expansion coefficient of Ln_(2)(Zr_(0.7)Ce_(0.3))_(2)O_(7)(Ln=La,Nd,Sm,Gd)increased,however the thermal conductivity is just the opposite.