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纳米SiO2氢氧化铝/十二烷基苯磺酸钠的表面包覆改性 总被引:1,自引:0,他引:1
通过氢氧化铝和十二烷基苯磺酸钠(SDBS)对纳米SiO2进行表面包覆和改性处理,改善纳米SiO2的表面结构和分散性.使用IR、FESEM、EDS、Malvern Zetasize 3000HSA自动电位粒度仪等表征手段,对表面包覆改性后纳米SiO2的表面结构、形貌及等电点等进行了测试和分析.结果表明,经Al(OH)3表面包覆后,纳米SiO2粉体等电点(IPE)的pH值从1.58变为7.1;经SDBS对表面包覆Al(OH)3的纳米SiO2进行改性后,纳米SiO2粉体团聚现象减少,单个纳米SiO2颗粒的粒径约为30nm. 相似文献
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以(C2H5)4SiO4、SnCl4·5H2O为原料,采用分步水解法制备以SnO2为芯材、SiO2为壳材的复合型SnO2-SiO2纳米颗粒,以扫描电镜(SEM)观察纳米材料的形貌,并用红外光谱(IR)、X射线光电子能谱(XPS)表征了SnO2-SiO2纳米颗粒的结构,研究不同核壳物质的量比的SnO2-SiO2纳米颗粒对明胶膜的抗静电性能的影响。结果表明:掺加SnO2-SiO2纳米颗粒的明胶膜具有良好的抗静电能力,随着复合颗粒加入量的增加,表面电导和明胶膜的光学密度都随之增加。 相似文献
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纳米TiO_2/SiO_2的制备与表征及其光催化活性的研究 总被引:2,自引:0,他引:2
针对二氧化钛(TiO2)纳米颗粒极易团聚、分散性差的问题,以提高TiO2分散稳定性与光催化活性为目的,采用并流中和法,以锐钛矿型纳米TiO2粉体为载体,硅酸钠(Na2SiO3)为包覆剂,使用硫酸(H2SO4)调节pH值,在纳米TiO2表面包覆致密的氧化硅(SiO2)膜。借助Fourier变换红外光谱(FTIR),X射线能量散射谱(EDS)和场发射扫描电子显微镜(FESEM)表征样品的键合情况、表面化学成分、分散性,同时借助紫外-可见分光光度计(UV-Vis Spectrophotometer)以亚甲基蓝的光催化降解反应对其光催化活性进行评价。FTIR和EDS结果表明:采用该包覆法后,SiO2以化学键合的方式沉积在纳米TiO2表面,在包覆层和纳米TiO2颗粒之间的界面上形成了Ti—O—Si键。SEM结果表明:TiO2/SiO2纳米复合粒子分散均匀,无严重团聚和大块堆积现象。光催化实验结果表明:以SiO2表面包覆后的TiO2颗粒光催化活性明显高于纯TiO2。 相似文献
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纳米SiO2制备及改性 总被引:1,自引:0,他引:1
为了改善纳米SiO2的分散性,用溶胶-凝胶技术制备了纳米SiO2凝胶,并用不同改性剂对粉末进行了表面改性.采用透射电子显微镜(TEM)、X射线衍射(XRD)、粒度分析仪(PSA)、紫外-可见光分光光度计(UV-VS)等分析了纳米SiO2的粒径及分散性.结果表明,正硅酸乙酯的水解和缩合反应条件直接影响纳米SiO2粉体的粒径大小.KH-550硅烷偶联改性剂用量、改性时间等因素对改性效果有明显的影响.当改性剂用量为4.1%(质量分数),改性时间为2h时,可得到高分散性的纳米SiO2粉体.纳米SiO2粉末易发生团聚,只有对其进行表面改性,才能得到疏水性纳米SiO2粉末. 相似文献
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纳米SiO2的表面改性及其在聚氨酯弹性体中的应用 总被引:13,自引:0,他引:13
用十二烷基苯磺酸钠(SDBS) 对表面包覆Al(OH)3的纳米SiO2进行了改性处理.通过IR、自动电位粒度仪和FESEM等测试手段对表面处理前后纳米SiO2的表面结构、界面电性能和分散状况进行了分析表征.考查了处理前后纳米SiO2与聚氨酯弹性体(PUE)的相容性及其对PUE材料力学性能的影响.结果表明,经SDBS对表面包覆Al(OH)3的纳米SiO2粉体进行改性后,纳米SiO2粉体的团聚现象减少,分散性提高,单个纳米SiO2颗粒的平均粒径约为30nm;经表面处理后的纳米SiO2粉体与有机基体PUE的相容性增强,并对PUE材料的力学性能有了较大的改善,能同时达到增强增韧的效果. 相似文献
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以新制备的过氧钨酸和酚醛树脂为原料合成碳化钨(WC)前驱体,分别以H2和Ar为还原及保护气体,原位碳化制备纳米WC粉体.使用FTIR、XRD及SEM对试样的理化特性进行表征,并采用循环伏安法测试Pt/WC复合材料的电化学催化活性及其稳定性.结果表明,实现了低温原位碳化制备纯度高的纳米WC粉体,粉体颗粒粒径为15~100nm,颗粒形貌近似球形.WC可与Pt协同作用加强H2的电催化氧化作用,10%Pt/WC(质量分数)展现了较好的催化稳定性和活性,其电流密度可达49.58mA/cm2. 相似文献
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Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state. 相似文献
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We prepared weakly agglomerated powders of ZrO2-CeO2 and HfO2-CeO2 solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO2. 相似文献
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Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·104 N/m2 and at a freon concentration of 0.25–0.8. 相似文献
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C. Bersier E. P. Stoll P. F. Meier T. A. Claxton 《Journal of Superconductivity and Novel Magnetism》2002,15(5):399-402
First-principles cluster calculations are reported of the local electronic structure of the three compounds: La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions. 相似文献
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A series of GRIN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-SiO2 systems. Negative radial refractive index profiles were generated by exchanging Na+ for Li+ ions in these glass rods. It has been observed that TiO2 plays a vital role in increase in the profile depth and maximum change in the refractive index because of its ambivalent nature. Change in the refractive index can be further increased by increasing the concentration of exchanging cation in the base glass. 相似文献
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I. R. Shein S. L. Skornyakov V. I. Anisimov A. L. Ivanovskii 《Journal of Superconductivity and Novel Magnetism》2014,27(1):155-161
The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr2Si2-type phases CaPd2As2 and SrPd2As2 in comparison with the non-superconducting CeMg2Si2-type phase BaPd2As2. Besides, the same properties were compared for CeMg2Si2- and ThCr2Si2-type polymorphs of BaPd2As2. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd2As2] with decisive contributions of Pd 4d states. The values of N(E F) increase in the sequence: CaPd2As2 < SrPd2As2 < BaPd2As2, i.e. in the reverse sequence relative to the transition temperatures T C. Thus, the change in T C cannot be explained by the electronic factor, i.e. by the simple correlation T C~N(E F). Most likely the decrease in T C in the sequence CaPd2As2 → SrPd2As2 and the absence of a superconducting transition in BaPd2As2 are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism. 相似文献
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本文给出了 Si_2N_2O-Al_2O_3-La_2O_3和 Si_2N_2O-Al_2O_3-CaO 系统的亚固相图。实验结果表明:在 Si_2N_2O-Al_2O_3-CaO 系统中有一个未知结构的新化合物 CaO·Si_2N_2O,在3CaO·Si_2N_2O 和3CaO·Al_2O_3两化合物之间形成连续立方固溶体。而 Si_2N_2O-Al_2O_3-La_2O_3系统中则没有发现新化合物。在两个系统的富 Si_2N_2O区,过量的 Si_2N_2O 与 La_2O_3和 CaO 分别反应形成 Si_3N_4与 La_(10)[SiO_4]_(?)N_2(H-相)(和 CaSiO_3。所研究的这两个三元系统中,分别形成了如下几个四元相容性区。在 Si_2N_2O-Al_2O_3-La_2O_3系统内有:H-Si_3N_4-La_2O_3·Si_2N_2O-La_2O_3·Al_2O_3;H-Si_3N_4-La_2O_3·Al_2O_3-La_2O_3·11 Al_2O_3;H-Si_3N_4-La_2O_3·11 Al_2O_3-Al_2O_3;H-Si_3N_4-Al_2O_3-O′s.s;H-Si_3N_4-O′s.s-Si_2N_2O在 Si_2N_2O-Al_2O_3-CaO 系统内有:Si_3N_4-CaSiO_3-CaO·Si_2N_2O-3CaO·Al_2O_3;Si_3N_3-CaSiO_3-3CaO·Al_2O_3-2CaO·Al_2O_3·SiO_(?);Si_(?)N_(?)-CaSiO_3-2CaO·Al_2O_3·SiO_2-Al_2O_3;Si_3N_4-CaSiO_3-Al_2O_(?)-O′s.s;Si_3N_4-CaSiO_3-O′s.s-Si_(?)N_(?)O 相似文献