發(fā)布時間：2018-05-15 18:08

  本文選題：Y_2SiO_5 + Yb_2SiO_5��； 參考：《北京交通大學》2017年碩士論文

【摘要】：隨著航空航天等領(lǐng)域的發(fā)展,對于綜合性能優(yōu)良的多孔陶瓷隔熱材料的需求日益突出。為了開發(fā)新型多孔陶瓷隔熱材料,本工作在RE-Si-O體系中選取熔點高、熱導率極低且高溫熱學和化學穩(wěn)定性較好的Y_2SiO_5和Yb2Si05作為基礎材料,采用水基冷凍干燥法制備具有高孔隙率的多孔陶瓷,并通過復合SiO_2氣凝膠和添加莫來石纖維的方式優(yōu)化多孔陶瓷的性能。以自制的Y_2SiO_5粉末為原料,采用水基冷凍干燥法制備多孔坯體,將坯體高溫燒結(jié)后成功制備出了具有高孔隙率的Y_2SiO_5多孔陶瓷。所制備的樣品是有著明顯方向性通孔和片層狀結(jié)構(gòu)的多孔陶瓷,孔徑尺寸分布在10～30μm且孔隙分布均勻。本文研究了漿料的固相含量和坯體的燒結(jié)溫度對Y_2SiO_5多孔陶瓷性能的影響,在漿料固相含量為15vol%、燒結(jié)溫度為1400℃情況下制備出綜合性能優(yōu)良的多孔陶瓷,具有較高的孔隙率(83.9%)和壓縮強度(1.62MPa),較低的熱導率(0.142W/(m·K))和密度(0.723g/cm3)。以同樣工藝制備了 Yb2Si05多孔陶瓷,樣品也具有較為優(yōu)良的力學性能和熱學性能,當漿料的固相含量從1Ovol%增加到25vol%時,樣品對應的孔隙率為85.4%～70.6%時,壓縮強度為1.75～6.92MPa,室溫熱導率為 0.107～0.302W/(m·K)。采用SiO_2氣凝膠填充Y_2SiO_5多孔陶瓷的孔隙,制備出了 SiO_2氣凝膠復合Y_2SiO_5多孔陶瓷。SiO_2氣凝膠的加入抑制了氣相傳熱、對流傳熱和輻射傳熱,明顯改善了 Y_2SiO_5多孔陶瓷的熱學性能,使熱導率降低20%以上;同時SiO_2氣凝膠加固了多孔骨架結(jié)構(gòu),改善了 Y_2SiO_5多孔陶瓷的力學性能,使壓縮強度提高了 50%以上。將莫來石纖維加入Y_2SiO_5多孔陶瓷,制備出了莫來石纖維增韌Y_2SiO_5多孔陶瓷。適量莫來石纖維的加入改善了 Y_2SiO_5多孔陶瓷的力學性能,當加入1Ovol%的莫來石纖維時,樣品的壓縮強度從1.62MPa上升到了 1.76MPa,熱導率從0.142W/(m·K)降低到了 0.123W/(m·K),并使樣品在壓縮實驗中呈現(xiàn)出一定的韌性特征,提高材料可靠性。本文采用水基冷凍干燥法成功制備了 Y_2SiO_5和Yb2Si05多孔陶瓷,并通過復合SiO_2氣凝膠和加入莫來石纖維的手段優(yōu)化了 Y_2SiO_5多孔陶瓷的性能。制備的RE-Si-O多孔陶瓷具有輕質(zhì)、低熱導率、高孔隙率、高強度和優(yōu)良的熱穩(wěn)定性,在高溫熱防護領(lǐng)域具有廣闊的應用前景。
[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，

本文編號：1893367