Despite La 2 Zr 2 O 7 ceramic fiber has been fabricated by electrospinning method, the effects of thermal pyrolysis process on the microstructures and properties of the fibers have seldom been considered. Three La 2 O 3 precursors were used to prepare La 2 Zr 2 O 7 ceramic fibers. Phase transformation of La 2 Zr 2 O 7 ceramic fibers were characterized by XRD and Raman spectra. The influence of the decomposition process on the microstructure of the fibers was studied by TG/DSC, XPS and SEM. The results show that slow weight loss leads to smaller grain size which could obtain higher strength fibers while fast weight loss could develop pores which are benefit to the decrease of the thermal conductivity .
Fei Liu,Yuntao Huang,Jingjing Qu,Qingzhi Xu,Jianping Ma,Qihan Chen,Lifu Lin
Pyrochlore-type zirconates, particularly La 2 Zr 2 O 7 , are considered highly promising materials for high-temperature applications owing to their excellent thermal and mechanical properties. However, the fabrication of high-performance La 2 Zr 2 O 7 ceramics with complex geometries remains challenging. In this study, dense La 2 Zr 2 O 7 ceramics with complex structures were fabricated via digital light processing (DLP) vat photopolymerization. The entire process was systematically examined, from raw material powder pre-calcination, suspension formulation optimization (including the selection of surface modifier KH570 and dispersant KOS110), rheological and curing behavior control, to green body debinding and final sintering. The results indicated that the La 2 O 3 /ZrO 2 powders pre-calcined at 1100 °C significantly suppressed cracking during the debinding process. By using 1 wt% KH570 as a surface modifier and 2 wt% KOS110 as a dispersant, a ceramic suspension with 35 vol% solid loading, low viscosity, and good stability could be obtained. The La 2 Zr 2 O 7 ceramic sintered at 1600 °C for 6 h achieved a high relative density of 99.23 %, a flexural strength of 257 ± 27 MPa, and a thermal conductivity of 3.4 W/m·K. The XRD and Raman analyses confirmed the improved crystallinity with increasing sintering temperature, and the observed changes in peak intensity were attributed to the densification and microstructural evolution. Finally, the complex La 2 Zr 2 O 7 ceramic structures were successfully fabricated, demonstrating the high shaping precision and the compact, uniform microstructure. This study provides an experimental basis for manufacturing high-performance La 2 Zr 2 O 7 ceramics using DLP technology.
De-bao Liu,Fei-fei Zhou,Li-jie Qu,Yi-guang Wang,Bao-sheng Xu,Shi-gang Ai
Porous La 2 Zr 2 O 7 ceramic aerogels (CAs) were prepared by sol-gel template method and thermal treated process. The microstructure and crystallisation behavior of the samples were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. The results indicated that the as-prepared porous La 2 Zr 2 O 7 CAs had a single-phase pyrochlore structure with typical three-dimensional (3-D) porous structure. Meanwhile, the formation mechanisms of the as-prepared porous La 2 Zr 2 O 7 CAs were investigated. At the same time, the as-prepared porous La 2 Zr 2 O 7 CAs presented an ultralow room-temperature thermal conductivity of 0.07 W/(m K), high specific surface areas of 325.17 m 2 /g, and a relatively high compressive strength of 11.95 MPa. What's more, the as-prepared porous La 2 Zr 2 O 7 CAs possessed ideal photocatalytic activities due to its high crystallinity, large surface area as well as unique 3-D porous structure. Therefore, the present work is proposing some new insight to prepare rare-earth zirconates CAs with porous structures for thermal insulation and dye degradation applications.
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