用羧酸铝和硅溶胶制备莫来石纤维

采用金属铝粉、甲酸和醋酸为原料,以氯化铝为催化剂制备了羧酸铝溶液。在羧酸铝溶液中加入硅溶胶,制备了可纺的前躯体溶胶。凝胶纤维在1400℃煅烧后,主要物相为莫来石,有少量的氧化铝和氧化硅相,得到的纤维直径均匀,但纤维表面有较多的裂纹。     

溶胶-凝胶法制备多晶莫来石连续纤维

以无水氯化铝、铝粉、正硅酸乙酯(TEOS)为原料,通过溶胶-凝胶法合成了双相莫来石溶胶,采用离心纺丝法制备了多晶莫来石连续纤维.结果表明,前驱体溶胶具有良好的纺丝性和稳定性.凝胶纤维1100℃热处理2h,由无定型态转变成γ-Al2O3相,1300℃纤维莫来石化.1400℃烧结后,纤维表面光滑、直径均匀.随着热处理温度的提高,晶粒逐渐长大.     

连续莫来石陶瓷纤维的制备研究

采用异丙醇铝和氯化铝作铝源,正硅酸乙酯作硅源,通过溶胶-凝胶法合成含有Al-O-Si长链的溶胶,干法纺丝制备莫来石连续纤维.对溶胶及凝胶进行了FT-IR分析和TG-DTA分析,研究了其光谱和热学性质,并对烧结后的纤维做SEM观察、XRD分析、XRF分析等.测试结果表明,在前驱体溶胶中含有Al-O-Si及Si-O-Si等为骨架的长链,具有较好的可纺性和稳定性;所得纤维直径在十几个微米,晶粒比较细小,在100～200nm之间;烧结过程中没有其它晶相出现.     

利用溶胶-凝胶法制备连续莫来石纤维

利用溶胶-凝胶法以氢氧化铝、羧酸、硅溶胶为原料、结合干法纺丝制备了连续莫来石陶瓷纤维。通过TEM、TG-DSC、FT-IR、XRD、SEM等方法对纺丝溶胶的微观结构、纤维晶型以及纤维表面和内部结构进行了研究,利用流变仪对溶胶的流变性能进行了研究。结果表明：通过溶胶-凝胶法制备的前驱体溶胶可纺性优异,性能稳定;采用干法纺丝得到的连续莫来石凝胶纤维表面光滑、直径均匀;经陶瓷化处理后获得连续莫来石纤维,纤维直径11～13μm,单丝拉伸强度可达1.9GPa,1200℃煅烧后主晶相为莫来石相。     

莫来石超细粉末的制备

以硝酸铝和正硅酸乙酯为主要原料 ,利用Sol-Gel方法制备了粒径分布范围窄的高纯莫来石超细粉末。运用DSC、TG、IR、XRD和激光粒度分析等技术对Sol-Gel工艺条件 ,以及莫来石超细粉末进行了分析研究。研究表明 ,在干凝胶的热处理过程中 ,非晶态的干凝胶首先转化为硅铝尖晶石 ,再由硅铝尖晶石转化为莫来石相 ;在 1 30 0℃下热处理可获得纯莫来石相的超细粉末 ,其粒径分布在 0 .4～ 1 .0 μm之间 ,平均粒径为 0 .5 4μm。结果表明 ,采用Sol -Gel方法可以制备出高纯、粒径分布范围窄的超细莫来石粉末。     

莫来石纳米粉的制备及表征

以正硅酸乙酯和硝酸铝为原料,采用溶胶-凝胶法制备出了超细的纳米莫来石.对于该方法的各种影响因素进行了实验分析,并对制得的样品进行了XRD,TG-DTA,TEM等性能表征.     

溶胶—凝胶法制备莫来石晶须

用正硅酸乙酯，硝酸铝为原料，采用溶胶－凝胶工艺制备了Ａｌ２Ｏ３－ＳｉＯ２干凝胶，通过高温热处理制得了直径为０．５－２．５μｍ，长径比为５－４０的莫来石晶须。采用ＸＲＤ，ＳＥＭ，ＴＥＭ和ＳＡＤＰ等手段研究了莫来石晶须的晶相组成，形貌与生长方向，发现莫来石晶须是沿其ｃ轴方向生长的。     

连续莫来石纤维应用与制备

综述了莫采石纤维的特性、应用、制备方法和研究现状,得出溶胶-凝胶法将成为制备连续莫来石纤维的趋势,并对该方法的发展方向进行了展望.     

TiO2纤维制备与应用研究进展

概述了TiO2纤维的发展历史和研究现状,对比分析了TiO2纤维的主要制备技术。结合作者的研究工作,重点探讨了溶胶-凝胶法制备TiO2纤维的影响因素。评述了近年来TiO2纤维在污染控制领域中的应用进展,对其发展前景进行了展望。     

溶胶—凝胶法莫来石被覆SiC复合微粒子的制备

本文采用溶胶－凝胶法以组成为３Ａｌ２Ｏ３．２ＳｉＯ２的混合溶胶分别于和压力条件下，对ＳｉＣ微细粉进行包覆处理，该涂覆层在低于１０００℃下经１ｈ热处理可结晶成莫来石层，研究了涂覆溶胶浓度、涂覆压力对涂层厚度、结晶化温度等的影响，涂覆后的ＳｉＣ微粉在中高温的表面抗氧化性明显提高。     

Synthesis of Mullite Whiskers

Mullite whiskers were synthesized by heating a mixture of SiO₂ and silicon in an alumina tube reactor under a flow of H₂ and CF₄. The length and diameter of the whiskers were several hundred micrometers and >15 μm, respectively. It was postulated that a vapor phase reaction between SiF₄ and AlF₃ made possible the synthesis of the large mullite whiskers.     

莫来石超细粉体的研究进展

对莫来石的结构、性能、应用、超细粉体的制备方法以及目前的研究进展作了综述.通过对莫来石的传统电熔法、烧结法、固相反应合成法、高能球磨低温煅烧法以及溶胶-凝胶法、水解-共沉淀法、喷雾热解法、水热法等制备方法的研究,为超细粉体制备提供了理论基础.并进一步探讨了在较低温度或其他溶剂的情况下,由水热法制取莫来石粉体以及对前驱体的体系用微乳分散剂进行优化的方法.     

Reactions and Microstructure Development in Mullite Fibers

Microstructural and compositional changes during heat treatment of sol–gel-derived mullite fibers with additions of 2 wt% B₂O₃, 2 wt% P₂O₅, 2 wt% Cr₂O₃, and (1 wt% P₂O₅+ 1 wt% Cr₂O₃) were compared with those of undoped mullite fibers. For all compositions the sequence of phase development was the crystallization of a spinel phase (†-Al₂O₃ or Al–Si spinel) from amorphous material, followed by the formation of mullite at higher temperatures. Differential thermal analysis showed that additions of B₂O₃ and P₂O₅ increased the temperature of spinel formation and that B₂O₃ significantly decreased the temperature of mullite formation. After 1 h at 1200°C, the size of mullite grains in fibers that contained B₂O₃ was less than 1000 Å the grains in fibers of other compositions were 6000 to 12000 Å. After 60 h at 1400°C, fibers modified with B₂O₃ had a grain size less than 2000 to 3000 Å the grains in fibers of other compositions were 6000 to 12000 Å. B₂O₃ was the most volatile additive.     

莫来石晶须的特性及应用

通过溶胶─凝胶工艺制备了莫来石前驱体,加入适当矿化剂经高温煅烧合成了高纯、单相莫来石晶须。XRD及SEM分析结果显示:晶须直径为50～100nm,长度为3～8μm,晶须尺寸均匀性好,表面光洁,直晶率高。运用所制备的晶须制备了多孔基板试样,并与普通粒子堆积法烧成样品显微结构与性能进行比较,进而分析了低维晶须材料与普通粒子的堆积成孔方式的异同。在此基础上,对莫来石晶须在其它方面的应用进行了展望。     

微硅粉原位合成莫来石制备高强度多孔陶瓷材料

本文用微硅粉和工业氧化铝粉为起始原料,马铃薯淀粉为造孔剂,通过原位反应烧结工艺制备了高强度多孔莫来石陶瓷材料.研究了不同烧结温度,不同淀粉含量对合成莫来石多孔陶瓷工艺影响.结果表明:以优化起始原料Al2 O3/SiO2摩尔比为3∶2.5,淀粉含量40 wt％,在1450℃温度下烧结样品孔隙率为36.07％、体积密度为2.02g/cm3时、热导率为1.40W· m-1 ·K-1,折强度达到79.91 MPa,莫来石纯度达95wt％.该工艺研究产品的研发为提高微硅粉附加值提供技术支撑.     

Synthesis of Submicrometer Mullite Powder via High-Temperature Aerosol Decomposition

High-purity mullite powders (3Al₂O₃.2SiO₂) have been prepared using a high-temperature aerosol decomposition technique yielding submicrometer (0.6 μm average) particles of spherical morphology with no hard agglomerates using aluminum nitrate and fumed silica as precursors. Depending upon the reaction conditions used, the powders range from amorphous to crystalline with no evidence of secondary-phase formation. This mullite synthesis approach has the advantages of not requiring postsynthesis milling, the ability to use a wide range of precursor systems, and enhanced control over chemical homogeneity and particle size/shape.     

Synthesis and Characterization of Lead Zirconate Titanate Fibers Prepared by the Sol–Gel Method: The Role of the Acid

Lead zirconate titanate (PZT) fibers are prepared by the sol–gel method using acetic acid and methacrylic acid to control the pH of the PZT precursor sol. The chemical evolution of the precursors, the thermal and crystallization behavior of the PZT gel fibers, and the microstructure of the samples with and without acid addition are analyzed and compared. It is observed that the properties of the fibers are improved when acids are used; particularly longer PZT ceramic fibers (4–5 cm) are obtained after heat treatment and a single perovskite phase is obtained at 550°C when using methacrylic acid. The mechanisms of the acid effect on the strengthening and crystallization of PZT fibers are discussed.     

Preparation of Short Mullite Fibers from Kaolin via the Addition of Foaming Agents

Short mullite fibers were fabricated by adapting the kneading–drying–calcination (KDC) process. The effect of foam forming on the formation of mullite fiber from kaolin via the KDC process, with the addition of a foaming agent, was examined. In the present study, doped sodium phosphates promoted the growth of mullite fiber and the formation of a glass matrix—effects that were ascribed to the P₂O₅ and Na₂O components, respectively, of the sodium phosphates. In particular, the addition of sodium phosphates greatly reduced the treatment time that was required for dissolution of the glass matrix in hydrofluoric acid. The addition of 10 mass% of sodium dihydrogen phosphate and calcination at 1500°C for 10 h were the optimum conditions for a short treatment time and the formation of long fibers.