多孔RE-Si-O三元陶瓷的制备与性能表征

发布时间：2018-05-15 18:08

  本文选题：Y_2SiO_5 + Yb_2SiO_5　； 参考：《北京交通大学》2017年硕士论文

【摘要】：随着航空航天等领域的发展,对于综合性能优良的多孔陶瓷隔热材料的需求日益突出。为了开发新型多孔陶瓷隔热材料,本工作在RE-Si-O体系中选取熔点高、热导率极低且高温热学和化学稳定性较好的Y_2SiO_5和Yb2Si05作为基础材料,采用水基冷冻干燥法制备具有高孔隙率的多孔陶瓷,并通过复合SiO_2气凝胶和添加莫来石纤维的方式优化多孔陶瓷的性能。以自制的Y_2SiO_5粉末为原料,采用水基冷冻干燥法制备多孔坯体,将坯体高温烧结后成功制备出了具有高孔隙率的Y_2SiO_5多孔陶瓷。所制备的样品是有着明显方向性通孔和片层状结构的多孔陶瓷,孔径尺寸分布在10～30μm且孔隙分布均匀。本文研究了浆料的固相含量和坯体的烧结温度对Y_2SiO_5多孔陶瓷性能的影响,在浆料固相含量为15vol%、烧结温度为1400℃情况下制备出综合性能优良的多孔陶瓷,具有较高的孔隙率(83.9%)和压缩强度(1.62MPa),较低的热导率(0.142W/(m·K))和密度(0.723g/cm3)。以同样工艺制备了 Yb2Si05多孔陶瓷,样品也具有较为优良的力学性能和热学性能,当浆料的固相含量从1Ovol%增加到25vol%时,样品对应的孔隙率为85.4%～70.6%时,压缩强度为1.75～6.92MPa,室温热导率为 0.107～0.302W/(m·K)。采用SiO_2气凝胶填充Y_2SiO_5多孔陶瓷的孔隙,制备出了 SiO_2气凝胶复合Y_2SiO_5多孔陶瓷。SiO_2气凝胶的加入抑制了气相传热、对流传热和辐射传热,明显改善了 Y_2SiO_5多孔陶瓷的热学性能,使热导率降低20%以上;同时SiO_2气凝胶加固了多孔骨架结构,改善了 Y_2SiO_5多孔陶瓷的力学性能,使压缩强度提高了 50%以上。将莫来石纤维加入Y_2SiO_5多孔陶瓷,制备出了莫来石纤维增韧Y_2SiO_5多孔陶瓷。适量莫来石纤维的加入改善了 Y_2SiO_5多孔陶瓷的力学性能,当加入1Ovol%的莫来石纤维时,样品的压缩强度从1.62MPa上升到了 1.76MPa,热导率从0.142W/(m·K)降低到了 0.123W/(m·K),并使样品在压缩实验中呈现出一定的韧性特征,提高材料可靠性。本文采用水基冷冻干燥法成功制备了 Y_2SiO_5和Yb2Si05多孔陶瓷,并通过复合SiO_2气凝胶和加入莫来石纤维的手段优化了 Y_2SiO_5多孔陶瓷的性能。制备的RE-Si-O多孔陶瓷具有轻质、低热导率、高孔隙率、高强度和优良的热稳定性,在高温热防护领域具有广阔的应用前景。
[Abstract]:With the development of aerospace and other fields, the demand for porous ceramic insulation materials with excellent comprehensive performance is becoming more and more prominent. In order to develop new porous ceramic insulating materials, Y_2SiO_5 and Yb2Si05, which have high melting point, low thermal conductivity and good thermal and chemical stability at high temperature, are selected as the basic materials in RE-Si-O system. Porous ceramics with high porosity were prepared by water based freeze-drying method. The properties of porous ceramics were optimized by composite SiO_2 aerogel and mullite fiber. Porous Y_2SiO_5 ceramics with high porosity were prepared by water based freeze-drying method from self-made Y_2SiO_5 powder. The samples are porous ceramics with obvious directional through pore and lamellar structure. The pore size distribution is 1030 渭 m and the pore size distribution is uniform. The effects of solid content of slurry and sintering temperature of billet on the properties of Y_2SiO_5 porous ceramics were studied in this paper. When the solid content of slurry was 15 volts and the sintering temperature was 1400 鈩，

本文编号：1893367