Silica aerogel due to the high specific surface area, nanometer level pores and low density of the micro structure, had excellent heat-insulating properties. But the characteristics of silica aerogel with low density ...Silica aerogel due to the high specific surface area, nanometer level pores and low density of the micro structure, had excellent heat-insulating properties. But the characteristics of silica aerogel with low density and high voidage resulted in poor mechanical properties. In order to improve the strength of materials and meet the actual needs, in this paper the heat-insulating composite material was made from the silica aerogel and mullite fiber. This kind of composite material mainly contented of mullite fiber, formed macro block structure, that gas gel is coated and filled with mullite fiber. Furthermore, the composite material had good strength and kept excellent thermal stability at 600°C. In addition the density of composite decreased with the increasing of the gas gel content.展开更多
The in-situ synthesized mullite bonded SiC ceramics for solar thermal tower plant were prepared from Silicon carbide （SIC）, manufactured aluminum hydroxide （Al（OH）3） and Suzhou kaolin via semi-dry pressing and p...The in-situ synthesized mullite bonded SiC ceramics for solar thermal tower plant were prepared from Silicon carbide （SIC）, manufactured aluminum hydroxide （Al（OH）3） and Suzhou kaolin via semi-dry pressing and pressureless firing. The results indicate that sample B3 （designed mullite content 15 wt%） fired at 1 400 ℃ exhibited optimal performance with a bending strength of 97.41 MPa. Sample B3 can withstand 30-cycles thermal shock without cracking （wind cooling from 1 100 ℃ to room temperature）, and the bending strength after thermal shock decreased by 17.92%. When the service temperature is 600℃, the thermal diffusivity, specific heat capacity, thermal conductivity and heat capacity are 6.48× 10-2 cm：.s-1, 0.69 kJ·kg-1. K-1, 9.62 W·m-1·K-1 and 977.76 kJ·kg-1, respectively. The XRD and SEM results show that SiC, mullite, or-quartz, and tridymite are connected closely, which gives the material a good bending strength. After 30-time thermal shock cycles, the structure of samples becomes loose. SiC grains are intersectingly arranged with rodshape mullite, exhibiting a favorable thermal shock resistance. The addition of Al（OH）3 and Suzhou kaolin can accelerate the synthesis of mullite, thus to reduce the firing temperature effectively. The volume effect of tfidymite is relatively small, improving the thermal shock resistance of materials. A higher designed muUite content yields a lower loss rate of bending strength. The mullite content should not be more than 15 wt% or else the bending strength would be diminished.展开更多
用铝型材厂废渣,高岭土和TiO2为主要原料固相烧结合成钛酸铝-莫来石复相材料。探讨不同原料配比对材料晶相及微观形貌的影响。采用X-射线衍射仪(X-Ray diffraction,XRD),扫描电镜(Scanning electron microscopy,SEM)及相关分析软件表征...用铝型材厂废渣,高岭土和TiO2为主要原料固相烧结合成钛酸铝-莫来石复相材料。探讨不同原料配比对材料晶相及微观形貌的影响。采用X-射线衍射仪(X-Ray diffraction,XRD),扫描电镜(Scanning electron microscopy,SEM)及相关分析软件表征复相材料的晶相组成和显微结构。研究结果确定最佳的原料配比为:铝型材厂废渣∶高岭土∶TiO2(质量比,下同)为:68∶13∶19,此时复相材料的主要相组成为钛酸铝(Al2TiO5):60.8%,莫来石固溶体(Al4.544Si1.456O9.368):22.7%,扫描电镜观察结果显示Al2TiO5晶体呈自形状,而莫来石固溶体主要以柱状和针状产出,材料体积密度达到3.53g/cm3,气孔率为9.8%,抗折强度为34.15MPa。展开更多
文摘Silica aerogel due to the high specific surface area, nanometer level pores and low density of the micro structure, had excellent heat-insulating properties. But the characteristics of silica aerogel with low density and high voidage resulted in poor mechanical properties. In order to improve the strength of materials and meet the actual needs, in this paper the heat-insulating composite material was made from the silica aerogel and mullite fiber. This kind of composite material mainly contented of mullite fiber, formed macro block structure, that gas gel is coated and filled with mullite fiber. Furthermore, the composite material had good strength and kept excellent thermal stability at 600°C. In addition the density of composite decreased with the increasing of the gas gel content.
基金Funded by the National Basic Research Program(973 Program)(No.2010CB227105)
文摘The in-situ synthesized mullite bonded SiC ceramics for solar thermal tower plant were prepared from Silicon carbide （SIC）, manufactured aluminum hydroxide （Al（OH）3） and Suzhou kaolin via semi-dry pressing and pressureless firing. The results indicate that sample B3 （designed mullite content 15 wt%） fired at 1 400 ℃ exhibited optimal performance with a bending strength of 97.41 MPa. Sample B3 can withstand 30-cycles thermal shock without cracking （wind cooling from 1 100 ℃ to room temperature）, and the bending strength after thermal shock decreased by 17.92%. When the service temperature is 600℃, the thermal diffusivity, specific heat capacity, thermal conductivity and heat capacity are 6.48× 10-2 cm：.s-1, 0.69 kJ·kg-1. K-1, 9.62 W·m-1·K-1 and 977.76 kJ·kg-1, respectively. The XRD and SEM results show that SiC, mullite, or-quartz, and tridymite are connected closely, which gives the material a good bending strength. After 30-time thermal shock cycles, the structure of samples becomes loose. SiC grains are intersectingly arranged with rodshape mullite, exhibiting a favorable thermal shock resistance. The addition of Al（OH）3 and Suzhou kaolin can accelerate the synthesis of mullite, thus to reduce the firing temperature effectively. The volume effect of tfidymite is relatively small, improving the thermal shock resistance of materials. A higher designed muUite content yields a lower loss rate of bending strength. The mullite content should not be more than 15 wt% or else the bending strength would be diminished.
文摘用铝型材厂废渣,高岭土和TiO2为主要原料固相烧结合成钛酸铝-莫来石复相材料。探讨不同原料配比对材料晶相及微观形貌的影响。采用X-射线衍射仪(X-Ray diffraction,XRD),扫描电镜(Scanning electron microscopy,SEM)及相关分析软件表征复相材料的晶相组成和显微结构。研究结果确定最佳的原料配比为:铝型材厂废渣∶高岭土∶TiO2(质量比,下同)为:68∶13∶19,此时复相材料的主要相组成为钛酸铝(Al2TiO5):60.8%,莫来石固溶体(Al4.544Si1.456O9.368):22.7%,扫描电镜观察结果显示Al2TiO5晶体呈自形状,而莫来石固溶体主要以柱状和针状产出,材料体积密度达到3.53g/cm3,气孔率为9.8%,抗折强度为34.15MPa。
