工艺因素对非水解溶胶-凝胶法制备钛酸铝纳米粉体的影响

以无水三氯化铝和四氯化钛为前驱体,正丁醇为氧供体,选择聚乙二醇(PEG)为分散剂,采用非水解溶胶-凝胶法(NHSG),低温合成钛酸铝纳米粉体.借助XRD、FT-IR、TEM等测试技术研究了反应前驱体浓度、凝胶化工艺以及PEG的加入顺序对钛酸铝纳米粉体合成及分散效果的影响.结果表明:随着前驱体浓度的减小,氯化醇盐之间的异质聚合反应变弱,导致钛酸铝合成效果的变差,但粉体团聚程度有减小的趋势,优选的前驱体浓度为2.25mol/L;与直接干燥、回流、容弹三种凝胶化工艺相比,回流结合容弹的凝胶化工艺因有助于形成更多的Al-O-Ti异质键合,因此具有更好的合成效果;在回流后加入PEG1000,既可保证钛酸铝的低温合成,又可抑制粉体的团聚,有利于制备分散性好、合成率高的钛酸铝纳米粉体.     

非水解溶胶-凝胶法低温合成钛酸钡粉体

以乙二醇和乙醇的混合液为复合溶剂,乙酸钡和钛酸丁酯为反应前驱体,采用非水解溶胶-凝胶(NHSG)法制备了钛酸钡粉体.借助XRD、FE-SEM、TEM、FTIR等研究了复合溶剂配比、钡钛比例以及热处理温度等工艺参数对合成BaTiO3的影响,探究了NHSG法合成BaTiO3的形成机理.结果表明:乙二醇用量过多或过少均不利于BaTiO3的合成;适当提高钛的用量可以提高BaTiO3的合成效果;优选溶剂比为2∶1,钡钛比为1∶1.1时可在550℃合成晶粒尺寸在40～60 nm范围的立方相BaTiO3粉体;非水解的反应机制是通过脱酯的缩聚反应实现了Ba和Ti原子级的均匀混合,然后直接晶化形成BaTiO3晶相.     

两种钛源对钛酸铝溶胶可纺性影响的对比研究

本文分别以钛酸丁酯的冰醋酸溶液和四氯化钛的乙醇溶液为钛源,硝酸铝的乙醇溶液为铝源,采用溶胶-凝胶法制备钛酸铝溶胶,通过分析溶胶的流变学特征和显微结构,研究了两种钛源对钛酸铝溶胶可纺性的影响.结果表明:以钛酸丁酯的冰醋酸溶液为钛源,制备的钛酸铝溶胶,由球形胶粒团聚体组成,呈非牛顿型流体的特性,溶胶不具有可纺性;而以四氯化钛乙醇溶液为钛源制备的溶胶,由线型聚合物构成,粘度为18.1～28 Pa·s,属于牛顿型流体,具有很好的可纺性.     

溶胶-凝胶法制备钛酸铝薄膜及其抗熔盐腐蚀性能

以钛酸四丁酯和硝酸铝为原料,乙醇为溶剂,通过溶胶-凝胶法在碳化硅基片上制备钛酸铝薄膜.借助DSC-TG、XRD、FE-SEM和SEM研究了钛酸铝干凝胶在热处理过程中的热重效应与相变化、薄膜的晶相组成、显微结构及其抗硝酸钠熔体腐蚀性能.结果表明:制备的钛酸铝薄膜表面均匀、致密,晶粒尺寸在100 nm左右,具有良好的抗硝酸钠熔体腐蚀性能.     

非水解溶胶-凝胶法低温制备铁稳定钛酸铝粉体

本文以无水二氯化铝和四氯化钛为前驱体,以无水乙醇为氧供体,以铁粉、三氯化铁和乙醇铁为稳定剂,采用非水解溶胶-凝胶法制备铁稳定钛酸铝粉体.运用XRD、FT-IR和热膨胀仪等测试手段研究和探讨了铁稳定剂对低温合成钛酸铝的效果、稳定作用及其机理.结果表明:引入铁粉既不能提高钛酸铝低温合成效果也不能改善其热稳定性;三氯化铁能促进钛酸铝的低温合成,但其稳定钛酸铝的效果也不明显;乙醇铁虽不利于低温合成钛酸铝,但却能够大大提高钛酸铝的抗热分解能力.乙醇铁能与前驱体混合液中形成的铝、钛醇盐形成异质缩聚键合,致使铁能进入钛酸铝晶格形成同溶体,从而提高其热稳定性能.     

NiTiO3薄膜的溶胶-凝胶工艺研究

以无机镍盐和钛酸四丁酯为起始原料,柠檬酸为络合剂,采用溶胶-凝胶法制备了NiTiO3薄膜.采用X射线衍射(XRD)、综合热分析仪(DSC/TG)、场发射扫描电镜(FESEM)对制备的薄膜进行了测试和表征.研究了保温时间,溶胶浓度对钛酸镍薄膜晶相组成、显微结构的影响.结果表明:保温时间为3 h,溶胶浓度为0.5 mol/L是制备NiTiO3薄膜的最佳工艺条件;随着保温时间的延长,薄膜的结晶度和致密度均有所提高;在1～0.5 mol/L的浓度范围内,溶胶浓度的降低有利于薄膜的生长.     

同轴静电纺丝制备仿生多孔氧化铝纤维研究

以无水氯化铝为原料,聚乙烯吡咯烷酮(PVP)为助纺剂,无水乙醇为溶剂,采用同轴静电纺丝法制备出氧化铝凝胶/PVP前驱体纤维,经1200℃煅烧后得到仿生多孔氧化铝纤维.系统研究了内外液流速以及PVP用量对多孔氧化铝纤维物相和孔结构的影响.结果表明,适当加大内液流速纤维逐渐出现仿生多孔结构,内液流速过大则会导致纤维多孔结构破裂消失.随着外液流速增加,纤维中的孔结构数量和孔径逐渐减小.增加PVP用量纤维直径增大,孔结构数量及孔径也会减小.当内液流速为0.1 mL/h,外液流速为1.0 mL/h,PVP用量为0.5g时,纤维为高纯α-Al203相,纤维表面光滑、连续,具有明显的仿生多孔结构.     

NiTiO3纳米晶的溶胶-凝胶制备工艺研究

以无机镍盐和钛酸四丁酯为起始原料,采用溶胶-凝胶法制备了NiTiO3纳米晶.采用X射线衍射(XRD)、综合热分析仪(DSC/TG)以及透射电镜(TEM)对制备的纳米晶进行了测试和表征.研究了不同镍源、后处理温度对钛酸镍纳米晶相组成以及显微结构的影响.结果表明:以硝酸镍为起始原料更易获得单一物相的NiTiO3纳米晶;以硝酸镍为原料,乙醇为溶剂,n(柠檬酸):n(Ni2++Ti4+)=1:1,后处理温度为700 ℃为制备NiTiO3纳米晶的最佳工艺条件.由谢乐公式推算得出NiTiO3晶粒生长符合Brook关系式,计算得到晶粒生长活化能为Ea=43.07 kJ/mol.     

Cr2O3和煅烧温度对铝钛渣制备钛酸铝材料性能影响（英文）

为了提高合成钛酸铝烧结性和钛酸铝的合成率,以铁合金厂铝钛渣和二氧化钛为主要原料,以Cr2O3为矿化剂,在不同煅烧温度下(1400℃、1450℃和1500℃)条件下,通过固相烧结方法合成钛酸铝材料。用XRD和SEM对煅烧后试样的矿物相组成和显微结构进行分析,用X’Pert plus软件计算合成材料中钛酸铝的晶格常数和晶胞体积。重点讨论了矿化剂Cr2O3加入量和煅烧温度对合成钛酸铝材料矿物相组成、晶格常数、显微结构及烧结性能的影响。结果表明,由于矿化剂中Cr3+对钛酸铝结构中Al3+和Ti4+的置换作用,钛酸铝晶体结构发生畸变。随着矿化剂Cr2O3加入量增大,钛酸铝晶胞常数和晶胞体积逐渐增大,置换作用所造成的结构缺陷加速了固相反应烧结,钛酸铝材料合成率逐渐增大。同时,随着煅烧温度的升高,结构中所产生的热缺陷也会促进合成钛酸铝的固相反应和烧结性,钛酸铝材料合成率增大,微观结构中裂纹数量逐渐减少。     

溶胶-凝胶法制备CuAlO2微晶及其合成活化能研究

采用溶胶-凝胶法制备了铜铁矿结构的CuAlO2微晶,利用示差扫描量热法(DSC)对其合成活化能进行了初步研究;通过XRD、TEM等分析方法对CuAlO2微晶的物相组成和显微结构进行表征.结果表明,以乙酸铜、硝酸铝和乙二醇为反应原料,采用溶胶-凝胶法可以成功制备CuAlO2微晶.前躯体在烧结过程中,首先生成了CuAl2O4和CuO中间相,然后继续反应再形成了CuAlO2微晶.DSC分析表明CuAlO2的合成温度在1181 ℃左右,计算得到其合成活化能为88.25 kJ/mol.利用紫外-可见光谱分析,CuAlO2微晶的光学带隙约为3.85 eV.     

复合碳源对C@ZrSiO4色料合成及色度的影响

采用稻壳和酚醛树脂作为复合碳源,无水四氯化锆和正硅酸乙酯为原料,氟化锂为矿化剂,通过非水解溶胶-凝胶法制备了C@ZrSiO4黑色包裹色料。分别利用X射线衍射( XRD)和透射电子显微镜( TEM)分析了色料的晶体结构和显微形貌,同时采用CIE-L? a? b?色度仪表征了样品的色度值。实验结果表明,酚醛树脂可以同时作为碳源和稻壳的分散剂,并且酚醛树脂和稻壳作为复合碳源制备的包裹黑色色料的发色效果优于使用单一碳源(稻壳或者酚醛树脂)制备的色料。当复合碳源添加量为硅酸锆2.50wt;时(其中酚醛树脂添加量为稻壳的15wt;),经1000℃氮气气氛热处理1 h后,可以制备出呈色良好的C@ZrSiO4黑色色料,色度值L?=39.02,a?=1.14,b?=2.68。     

Spinnablity and structure characterization of mullite fibers via sol–gel-ceramic route

Viscosity and rheology behaviors of the mullite sols prepared from aqueous solution of aluminum nitrate, aluminum isopropoxide and tetraethylorthosilicate has been investigated. Rheological measurement suggested that mullite sols exhibited good spinniabilty when the evaporation of the solvent is allowed during sol–gel process. Spinnable sols showed shear-thinning flow behavior with high viscosity to the time of gelation. By adjusting temperature, the gelation degree and viscosity of the sol could be stabilized at a certain value and the sol–gel transition could be transferred to the spinning line of a laboratory dry-spinning apparatus. Continuous mullite fibers were obtained from such sols using sol gel dry-spinning method. The final ceramic fibers had smooth surfaces with an average diameter of 50 μm. Structure evolution of mullite ceramic fibers were characterized by MAS NMR and specific surface area analyses.     

An alumina mat with a nano microstructure prepared by centrifugal spinning method

Ceramic fiber products specially alumina mat because of low thermal conductivity and high melting point are used as high temperature insulating materials. Alumina has so high melting point (T_m > 2040 °C) that its mat can be produced through sol–gel method. In this research alumina mat has been manufactured by sol–gel spinning method using our laboratory-designed centrifugal spinneret. The desired viscosity of sol for spinning is 150 P. Phase transformation of the product begins at 600 °C and there is not any amorphous phase at 800 °C and theta alumina (θ-Al₂O₃) is the main phase. In this work, transformation of transitional phase to alpha alumina (α-Al₂O₃) takes place from 1000 °C to 1200 °C. The optimum percent of silica in alumina mat is 4 wt%. Fibers constitute network structure that their average diameter is about 10 μm and contains very fine grains (100 nm). The silica percent concerning the limits of this study (<10 wt%) does not effect on fiber diameter, but grain size decreases from about 200 nm to less than 100 nm while increasing silica percent.     

碳纳米管吸波性能研究

碳纳米管和环氧树脂混合制成复合吸波涂料,浇铸在铝板上制成吸波涂层.用TEM检测碳纳米管,反射率扫频测量系统HP8757E标量网络分析仪检测吸波性能.碳纳米管和环氧树脂比例为1:100时,7mm厚吸波层试样在11GHz和17.83 GHz出现双吸波峰,最大吸波峰出现在17.83 GHz,峰值R为-9.04dB,带宽约1GHz(R＜-8dB).吸波涂层厚度不变,碳纳米管和环氧树脂比例调整为8:100时,双吸波峰出现在10.08GHz和16.80GHz,带宽分别达到2.87GHz和2.56GHz,总带宽5.43GHz(R＜-8dB).当R＜-5dB,带宽达到11.20GHz.最大吸波峰出现在10.08GHz,峰值加大到R为-21.08dB.     

Drug release from biodegradable silica fibers

Sol-gel derived biodegradable SiO₂ gel fibers have been prepared and characterized by Raman spectroscopy, SEM, ²⁹Si MAS NMR and TG-MS, respectively. An active component, dexmedetomidine hydrochloride, was incorporated in situ into the fiber structure, by adding it to the sol used for fiber spinning. The subsequent release of the active component was studied in vitro and shown to be determined by differences in the fiber structure, for which clear but indirect evidence was obtained from the different characterization methods used.     

微乳液电纺丝法制备Eu3+掺杂锆酸镧多孔纤维及其发光性能研究

以LaCl₃、ZrClO₂·8H₂O为原料,无水乙醇为溶剂,采用微乳液静电纺丝法制得烧绿石型的锆酸镧纤维,并引入分相剂石蜡在纤维中构筑多孔结构.采用XRD、SEM和BET研究了纤维的结构和形貌,采用PL光谱测试了Eu³⁺掺杂的锆酸镧纤维的发光性能.研究表明,引入分相剂石蜡可以改善纤维中的孔结构,当石蜡用量为4 mL时所制备的锆酸镧纤维物相纯度高,其比表面积为20.77 m²·g^-1,平均孔径19.3 nm,有较为丰富的孔结构且分布均匀.因此,在该纤维中掺杂Eu³⁺后,由于氧离子与稀土离子间的电荷跃迁,以及多孔结构光散射的作用,多孔纤维的发光强度有所提高.     

Formation of silica/epoxy hybrid network polymers

Epoxy-based inorganic–organic hybrid polymers, for use as a matrix in coatings, have been prepared from 3-glycidoxypropyltrimethoxysilane by a sol–gel process. The precursor molecule possesses both epoxy and silicon alkoxide functionality and so interlinked inorganic–organic networks can be formed. Diethylenetriamine was used to open the epoxy rings and form the organic network to an extent determined by the initial ratio of amine to epoxy groups. The materials were cured either at room temperature or with an additional heat treatment at 150 °C. Structural characterisation of the cured hybrid materials was performed using a combination of Raman, and ²⁹Si and ¹³C MAS NMR spectroscopies. These show that the formation of the two networks does not occur independently and the rate or extent of organic cross-linking has a direct effect on the extent of the inorganic network formation, and vice-versa.     

Particle-reinforced water-based organic–inorganic nanocomposite coatings for tailored applications

We report the synthesis and characterization of three particle-reinforced water-based nanocomposite coatings. The films are sol–gel derived using non-ionic surfactant, with aluminum perchlorate (Al(ClO₄)₃) as a catalyst and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursor. Through the aid of nanoparticle colloids and a minute amount of catalyst, dense, hard and monolithic materials are obtained. Incorporating metal oxide nanoparticles brings forth unique properties, such as absorbing harmful UV radiation. Silica colloid composites provide greatly enhanced mechanical properties without modifying the unique optical properties of inorganic materials. Water-based synthesis of these coatings is straightforward and produces very few harmful byproducts, making them ideal materials in industry. The materials presented are relatively hard and abrasion resistant with very good adhesion; two of the coatings are UV absorbent. Various colloids can be employed in our methods to tailor properties and resulting materials may serve applications such as optical, protective, catalytic, guest-host, and multifunctional coatings.     

Characterization of optical properties of amorphous BaTiO3 nanothin films

Amorphous barium titanate nanothin films were prepared by sol–gel dip-coating method. According to transmission spectrum, the refractive index and optical band gap of nanothin films have been determined. High transmission spectrum without any fluctuation in visible wavelength region was recorded. Experimental results indicated that the surface morphology of prepared nanothin films were improved and as a result of that, a better optical properties, less optical losses and higher band gap width were obtained in contrast with other reported data. It was found that optical propagation loss of BaTiO₃ nanothin film was much lower than normal polycrystalline BaTiO₃ thin film. It seems to us that, amorphous barium titanate nanothin films would be suitable for several applications.     

Flexible and high ion conducting solid polymer electrolytes prepared via ring-opening polymerization

Abstract

The chemical cross-linking of epoxy resin has been known as an imperative way to improve the mechanical strength and thermal stability of solid polymer electrolytes (SPEs). Herein, we prepare flexible epoxy-based SPEs with high ion conductivity for electrochemical devices via ring-opening polymerization. A diglycidyl ether of bisphenol-A (DGEBA) epoxy resin was selected as the mechanical supporting SPE matrix. The high flexibility of SPEs can be obtained by adding poly(ethylene glycol) diglycidyl ether (PEGDE) plasticizer to the epoxy resin. Furthermore, the incorporation of electrolyte mixture of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salts and 1-butyl-3 methylimidazolium bis(trifluorosulfonyl)imide (BMIM-TFSI) ionic liquids allows for boosting ionic conductivity of the epoxy-based SPEs. Consequently, the high room temperature ionic conductivity ～2.4?×?10^?3 S/cm was achieved in the SPE containing 30?wt% of the epoxy and 70?wt% of the electrolyte mixture.