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Structure evolution and thermal stability of La_2O_3-doped mullite fibers via sol-gel method 被引量:2
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作者 王炜 翁端 吴晓东 《Journal of Rare Earths》 SCIE EI CAS CSCD 2012年第2期175-180,共6页
The lanthana-doped mullite fibers were prepared via a sol-gel method from the aluminum isopropoxide-aluminum nitrate-tetraethyl orthosilicate system. The structure evolution and thermal stability of the mullite fibers... The lanthana-doped mullite fibers were prepared via a sol-gel method from the aluminum isopropoxide-aluminum nitrate-tetraethyl orthosilicate system. The structure evolution and thermal stability of the mullite fibers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and trans-mission electron microscopy (TEM). The results showed that the fibers obtained after calcination at 1000℃ was in the form of Al2O3-rich mullite, which tended to transform to stoichiometric mullite with the lanthana content increasing. The lattice parameter a exhibited a decline trend with the lanthana content increasing, while b showed an upward tendency. Correspondingly, the redshift of Si-O-Si bond from 1255 to 1245 cm-1 was observed. The grain growth was inhibited for the doped fibers, among which the 5% La2O3-doped sample presented a mini-mum crystallite size (17.2 nm) after calcination at 1000 ℃ for 1 h. 展开更多
关键词 mullite fibers lanthana doping phase transformation grain growth rare earths
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Preparation of three-dimensional braided carbon fiber reinforced mullite composites from a sol with high solid content 被引量:1
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作者 Wei ZHANG Qing-song MA +1 位作者 Ke-wei DAI Wei-guo MAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第11期2249-2255,共7页
To prepare the three-dimensional braided carbon fiber reinforced mullite (3D C/mullite) composites, an Al2O3-SiO2 solwith a solid content of 20% (mass fraction) and an Al2O3/SiO2 mass ratio of 2:1 was selected as... To prepare the three-dimensional braided carbon fiber reinforced mullite (3D C/mullite) composites, an Al2O3-SiO2 solwith a solid content of 20% (mass fraction) and an Al2O3/SiO2 mass ratio of 2:1 was selected as the raw material. Characteristics andmullitization of the sol were analyzed throughly. It is found that the formation of mullite is basically completed at 1300℃ and thegel powders exhibit favorable sintering shrinkage. The 3D C/mullite composites without interfacial coating were fabricated throughthe route of vacuum impregnation-drying-heat treatment. Satisfied mechanical properties with a flexural strength of 241.2 MPa anda fracture toughness of 10.9 MPa·m1/2are obtained although the total porosity reaches 26.0%. Oxidation resistances of the compositesat 1200, 1400 and 1600 ℃ were investigated. Due to the further densification of matrix, the 3D C/mullite composites show tiny massloss and their mechanical properties are well retained after oxidation at 1600 ℃ for 30 min. 展开更多
关键词 carbon fiber reinforced mullite composites Al2O3-SiO2 sol mechanical properties oxidation resistance
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Preparation and catalytic performance of La_(0.8)Sr_(0.2)CoO_(3) supported on the mullite fiber ceramic
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作者 ZENG Lingke LIU Yanchun +3 位作者 DUAN Bilin LIU Ping’an WANG Hui SHUI Anze 《Frontiers of Chemical Science and Engineering》 SCIE EI CSCD 2007年第4期372-376,共5页
The perovskite-type La_(0.8)Sr_(0.2)CoO_(3) supported on the mullite fiber porous ceramics was prepared by means of the impregnating method,and was then characterized by scanning electron microscopy(SEM)and X-ray diff... The perovskite-type La_(0.8)Sr_(0.2)CoO_(3) supported on the mullite fiber porous ceramics was prepared by means of the impregnating method,and was then characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD);thus we can come to the conclusion that the perovskite-type composite oxidant can disperse on the surface of mullite fiber ceramics.The catalytic activity of the La_(0.8)Sr_(0.2)CoO_(3) for NO and CO was evaluated.The effect of the doped 0.1 wt-%PdCl_(2) on the catalytic activity of the perovskite-type La_(0.8)Sr_(0.2)CoO_(3) was also discussed.The results show that the conversion rates of NO and CO respectively reaches 74.5% and 99% at 601℃ without doped Pd,and both reach 100%at 350℃ with a little doped Pd. 展开更多
关键词 Perovskites-type La_(0.8)Sr_(0.2)CoO_(3) mullite fiber porous ceramics support PALLADIUM catalytic activity
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