方铁辉1?覮,张修旷1,黄建平1,2,刘彬彬3,吕铁铮1,2.La2Ce2O7@La2Zr2O7核壳结构纳米粉体的 制备及其抗烧结性能[J].湖南大学学报:自然科学版,2020,(6):132~140
La2Ce2O7@La2Zr2O7核壳结构纳米粉体的 制备及其抗烧结性能
Preparation and Sintering Resistance of Core-shell La2Ce2O7@La2Zr2O7 Nano-powder
  
DOI:
中文关键词:  热障涂层  核壳纳米粒子  水热合成  烧结实验
英文关键词:thermal barrier coatings  core shell nanoparticles  hydrothermal synthesis  sintering tests
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作者单位
方铁辉1?覮,张修旷1,黄建平1,2,刘彬彬3,吕铁铮1,2 (1. 湖南大学 材料科学与工程学院湖南 长沙 410082 2. 湖南工学院 汽车零部件技术研究院湖南 衡阳 421002 3. 湖南大学 现代工程训练中心湖南 长沙410082) 
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中文摘要:
      针对La2Ce2O7抗烧结性能较差,La2Zr2O7的热膨胀系数较低的性能特点,采用水热法合成了La2Ce2O7内核,然后通过共沉淀法成功制备La2Ce2O7@La2Zr2O7核壳结构纳米粉体. 将粉体预压成块,分别在1 100 ℃、1 300 ℃和1 500 ℃下进行了不同时间的烧结测试及在1 100 ~1 500 ℃烧结6 h以考察温度对其抗烧结性能的影响. 采用扫描电镜、透射电镜、能谱仪分析了材料的形貌和成分,并测试了试样的密度和显微硬度. 结果表明,La2Ce2O7内核具有立方结构或八面体结构外形,粒径约200 nm. La2Zr2O7壳层为非晶体,形成了包覆效果良好的La2Ce2O7@La2Zr2O7核壳结构. 等温烧结时,核壳结构的密度变化率保持在2.1%以内,远低于La2Ce2O7和La2Zr2O7,孔隙和晶粒尺寸分布均匀,无裂纹和烧结现象出现. 当烧结温度在1 300 ℃以内时,核壳结构组织均匀,多孔,密度变化率稳定在10.6%以内,晶粒尺寸约维持在450 nm,晶粒长大速率与La2Zr2O7接近,抗烧结性能良好;当烧结温度高于1 300 ℃时,核壳结构孔隙增大且晶粒迅速长大,致密化加快,晶粒长大速率也变快,与La2Ce2O7接近,出现明显烧结现象;其显微硬度稍高于La2Ce2O7,而远低于La2Zr2O7.
英文摘要:
      In view of the poor sintering resistance of La2Ce2O7 and the low thermal expansion coefficient of La2Zr2O7,the La2Ce2O7 core was first synthesized by hydrothermal method, and then the La2Ce2O7@La2Zr2O7 core-shell nano-powder was successfully synthesized by coprecipitation method. The powder was pre-pressed into pellets and then sintered at 1 100 ℃、1 300 ℃ and 1 500 ℃ for different hours and sintered at 1 100 ~1 500 ℃ for 6 hours, so as to investigate the effect of temperature on its sintering resistance. The morphology and composition of the materials were analyzed by scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometer. The density and micro-hardness of the samples were also tested. Experimental results showed that the La2Ce2O7 core had a cubic or octahedral shape with the average size of about 200 nm. The La2Zr2O7 shell was amorphous structure, and exhibited good enveloping effect on forming a La2Ce2O7@La2Zr2O7 core-shell structure. Constant temperature sintering tests found that the density change rate of the core-shell structure was kept within 2.1%, which was much lower than that of La2Ce2O7 and La2Zr2O7. The distribution of pore and grain size was uniform without cracks and sintering. When sintering temperature was below 1 300 ℃, the La2Ce2O7@La2Zr2O7 was uniformly porous, its density change rate was stable within 10.6%, the grain size was maintained at about 450 nm, and the grain growth rate was close to that of La2Zr2O7,proving its good sintering resistance. When the temperature was higher than 1 300 ℃, however, obvious sintering phenomenon occurred. The densification of La2Ce2O7@La2Zr2O7 accelerated, and its pore size increased and grains grew rapidly, nearly reaching to that of La2Ce2O7. Moreover, the micro-hardness of La2Ce2O7@La2Zr2O7 was slightly higher than that of La2Ce2O7,but much lower than that of La2Zr2O7.
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