一种基于SiO2 气凝胶制备超疏水表面的工艺探讨

以商品化SiO2气凝胶为原料,选择不同的分散介质进行分散,然后在玻璃表面进行涂覆并干燥,制得超疏水表面。研究结果表明:当选择丙酮作为分散介质,SiO2气凝胶质量浓度为30g/L,以旋涂的方式涂覆2次,并于20℃进行干燥时,所制备的表面超疏水效果最好,其接触角为153.2°,滞后角为1.7°。     

TiO2/SiO2复合薄膜对玻璃亲水性的影响

目的解决玻璃的防雾问题。方法采用溶胶-凝胶法在玻璃表面涂覆SiO2和TiO2复合薄膜,以改变玻璃表面的亲水性。通过全因素试验研究了SiO2溶胶的制备温度、SiO2薄膜的层数及TiO2薄膜的层数对玻璃亲水性的影响。结果 SiO2溶胶的制备温度对玻璃的亲水性影响最大,其次是SiO2层数,最后才是TiO2的层数。随SiO2溶胶的制备温度的升高,以及SiO2层数和TiO2层数的增加,玻璃的亲水性先上升,后基本保持不变。结论玻璃表面亲水改性最佳制备工艺条件是SiO2溶胶制备温度为60℃,2层SiO2薄膜和2层TiO2薄膜。     

低介电常数纳米氧化硅薄膜(英文)

介绍了一种新制备低介电常数 SiO2薄膜的方法。以 TEOS 为前躯体、盐酸为催化剂、CTAB 作为模版剂,采用溶胶-凝胶法制备硅溶胶,以浸渍提拉法制备薄膜。采用 FITIR、XRD 和 AFM 等方法表征了薄膜,并用阻抗分析仪测量介电常数。结果表明,通过调节 CTAB 的浓度和老化时间可以制得介电常数小于 2.2 的 SiO2 薄膜,薄膜拥有较好的机械强度和耐刮擦性,通过采用六甲基二硅胶烷(HMDS)对薄膜表面进行修饰,可以提高薄膜的疏水性能从而提高其在空气中的稳定性。     

溶胶-凝胶法制备超疏水性纳米复合防腐涂层

通过溶胶-凝胶旋涂法在不锈钢基底上制备了具有超疏水性能的介孔碳复合SiO2涂层。通过TEM,SEM及静态接触角、电化学测试技术(Tafel和EIS)等对其结构、疏水性能和耐蚀性等进行表征。结果表明:在不锈钢基底上形成了乳突状形貌,水在涂层表面静态接触角达到163°。该超疏水性SiO2/介孔碳复合涂层具有优良的防腐性能。     

乳液模板法制备硅基蜂窝状结构超疏水薄膜及薄膜表征

采用硅溶胶和聚合物乳液混合的方法制得含硅聚合物杂化乳液,然后通过简单的浸渍提拉法在玻璃基片上获得薄膜,薄膜经热处理后,在乙醇中经三甲基氯硅烷修饰,获得了超疏水性能.根据薄膜的表面形貌及其与水的宏观接触角,研究了苯乙烯单体加入量和SiO2溶胶/PS乳液体积比对薄膜疏水性能的影响,并分析了薄膜超疏水的原因.结果表明:热处理...     

玻璃表面二氧化硅基超疏水膜的研究进展

超疏水表面带来一些可贵的界面性质,包括防结冰、防污染、防氧化等。对于工业产品中常用的玻璃等无机材料,研究人员参照自然界超疏水物质的结构和成分,借助含碳、氟等元素的物质,通过各种方法,合成具有微米-纳米二重粗糙结构和低表面能的有机-无机杂化涂层与基材结合,从而制备超疏水表面。因玻璃表面亲水性的固有性质,在平板显示、触摸屏、太阳电池盖板、玻璃幕墙等领域,解决既能满足光学性能指标,又能实现疏水性和抗污染性的问题尤为重要。首先讨论了粗糙表面的固液复合接触和非复合接触两种理论模型,进而阐述了超疏水玻璃的实现要素和基于二氧化硅的超疏水膜的制备方法。梳理了以溶胶-凝胶法为基础的玻璃表面二氧化硅基透明超疏水膜的制备技术进展,根据涂膜次数、溶胶组成、膜层粗糙结构的实现方法等,将现有制备技术分类、归纳为三种制备路线：共前驱体合成改性二氧化硅溶胶制备单层超疏水膜,表面改性法制备多层结构超疏水膜,添加二氧化硅颗粒引入粗糙层法。指出了各种方法的超疏水原理、膜层特点,分析了部分制备实例的疏水性、粗糙结构、光学透过率等性质的影响因素。对于溶胶-凝胶法制备的SiO2基超疏水玻璃,实现超疏水性的同时,如何保持玻璃良好的透明性以及膜层的耐磨性、持久性,是需要重点研究的方向。     

纤维掺杂疏水SiO2气凝胶的制备与表征

采用溶胶-凝胶方法成功制备了陶瓷纤维掺杂的疏水SiO2气凝胶.陶瓷纤维在SiO2气凝胶中起骨架支撑的作用来提高气凝胶的机械性能.SiO2气凝胶的机械强度从没有掺杂纤维的1.6×104Pa提高到掺杂10%纤维的9.6X 104Pa,且掺杂10%纤维的SiO2气凝胶常温常压的热导率仅为0.029 W/(m·K).掺杂SiO2气凝胶的疏水性通过表面修饰也得到了极大的提高.     

常压干燥法的疏水型低介电常数气凝胶薄膜

气凝胶薄膜具有超低的介电常数,在超大规模集成电路互连系统中有着巨大的应用潜力.采用溶胶-凝胶技术,通过酸/碱二步法控制实验条件,结合低表面张力溶剂替换以及CH3非活性基团置换修饰、超声振荡等,不需要超临界干燥,而仅在常压下就可以通过简单的提拉过程制备出疏水型低介电常数气凝胶薄膜.测得的红外透射光谱表明所制备的薄膜由于掺入甲基基团而疏水,接触角测试值约120°,制备过程中充分注意到稀释、老化、有机修饰表面、热处理和提拉条件对膜的影响,使其过程达到最佳.热处理温度在150～650℃,采用6%三甲基氯硅烷时,制得的疏水型气凝胶薄膜折射率为1.08～1.12,介电常数为1.62～1.92.     

纳米多孔SiO_2气凝胶的表面修饰和吸附特性(英文)

采用溶胶-凝胶法,通过表面修饰等工艺,在常压条件下制备出高气孔率的疏水性 SiO2气凝胶。表面修饰能够调节气凝胶内部纳米多孔结构和增大比表面积。表面修饰采用三甲基氯硅烷,其 Si-CH3基团能取代原有气凝胶表面的 O-H 基团,使其具有疏水特性。用扫描电镜,红外光谱以及孔径分布仪对其结构和表面基团进行了表征,对其吸附特性进行了测试。结果表明,SiO2 气凝胶具有纳米多孔结构,且有较好的疏水特性,其吸附性能较活性炭纤维和活性炭颗粒高 3～4 倍,再吸附容量基本不变,是一种极好的高吸附材料,具有广阔应用前景。     

界面效应对小球藻在钛合金表面附着的影响

采用激光刻蚀技术在钛合金表面分别构筑网格、直线、点阵3种微结构,采用溶胶-凝胶法将纳米SiO2粒子涂覆在微结构上,制备分别具有微结构/微纳结构的疏水/超疏水表面.利用小球藻附着面积评价表面的抗海洋生物附着性能,利用动态冲刷实验评价小球藻的附着强度.结果显示:具有微结构的疏水/超疏水表面符合Wenzel模型,具有微纳结构的超疏水表面符合Cassie模型,且其表面抗附着性能更优,附着强度更小;网格表面的超疏水自清洁性能最强,抗附着性能最优,附着强度最小,其次是直线,再次是点阵;随着微结构间距的增大,接触角减小,滚动角增大,抗附着性能降低,附着强度增大.     

改进型镁扩散法制备高临界电流密度MgB2超导体性能研究

本文采用一种改进型镁扩散法成功制备出密度达到1.95g/cm₃的MgB₂超导块材。论文研究了不同的热处理条件对MgB₂块材的超导转变温度(T_c)和临界电流密度(J_c)性能的影响。采用最佳热处理条件制备的MgB₂超导体T_c和J_c分别达到了38.1K和0.53MA/cm₂(10K,自场)。为了改进镁扩散法MgB₂超导体中弱的高场磁通钉扎性能,本文还研究了nano-Pr₆O₁₁和C掺杂对MgB₂超导体的临界电流密度和不可逆场(H_irr)的影响。结果表明C掺杂的MgB₂超导体临界电流密度在10K,6T下达到了10₄A/cm₂,该结果比未掺杂MgB₂超导体在同样条件下性能提高了两个量级,甚至比固态反应法制备的nano-C掺杂MgB₂超导体性能更好。利用该方法制备的nano-Pr₆O₁₁掺杂的MgB₂超导体在10K,2T下也比未掺杂样品J_c提高达9.4倍。根据大量的实验结果和理论分析我们提出基于改进型镁扩散法和化学掺杂,包括纳米粒子和C掺杂,很有可能是一种制备高性能MgB₂超导体非常有效的途径。     

废旧锂离子电池中Li, Fe和V的回收及xLiFePO4-yLi3V2(PO4)3的制备

由于LiFePO_4和Li_3V_2(PO_4)_3材料的特征相近,制备方法类似,提供了一种从废旧LiFePO_4和Li_3V_2(PO_4)_3混合电池中回收Li、Fe和V,再制备xLiFePO_4-yLi_3V_2(PO_4)_3的方法。在空气气氛中600℃热处理1h后,去除粘结剂PVDF使活性物质与集流体分离。调节Li、Fe、V和P摩尔比,球磨、锻烧,配制不同比例的xLiFePO_4-yLi_3V_2(PO_4)_3(x:y=5:1,7:1,9:1)复合电极材料。表征了其形貌、结构和电化学性能,结果表明,回收制备的复合材料将同时具备LiFePO_4和Li_3V_2(PO_4)_3两种材料的电化学性能,能显著改善LiFePO_4的倍率性能。     

Improved capacity and rate capability of Ru-doped and carbon-coated Li4Ti5O12 anode material

Pure Li₄Ti₅O₁₂, modified Li₄Ti₅O₁₂/C, Li₄Ru_0.01Ti_4.99O₁₂ and Li₄Ru_0.01Ti_4.99O₁₂/C were successfully prepared by a modified solid-state method and its electrochemical properties were investigated. From the XRD patterns, the added sugar or doped Ru did not affect the spinel structure. The results of electrochemical properties revealed that Li₄Ru_0.01Ti_4.99O₁₂/C showed 120 and 110 mAh/g at 5 and 10 C rate after 100 charge/discharge cycles. Li₄Ru_0.01Ti_4.99O₁₂/C exhibited the best rate capability and the highest capacity at 5 and 10 C charge/discharge rate owing to the increase of electronic conductivity and the reduction of interface resistance between particles of Li₄Ti₅O₁₂.It is expected that the Li₄Ru_0.01Ti_4.99O₁₂/C will be a promising anode material to be used in high-rate lithium ion battery.     

The high-temperature corrosion behavior of Nb-Al alloys in a H2/H2S/H2O gas mixture

The corrosion behavior of pure Nb and three Nb Al alloys containing 12.5, 25, and 75 at.% Al was studied over the temperature range of 800–1000°C in a H₂/H₂S/H₂O gas mixture. Except for the Nb-12.5Al alloy consisting of a two phase structure of -Nb and Nb₃Al, other alloys studied were single phase. The corrosion kinetics followed the parabolic rate law in all cases, regardless of temperature and alloy composition. The parabolic rate constants increased with increasing temperature, but fluctuated with increasing Al content. The Nb-75Al alloy exhibited the best corrosion resistance among all alloys studied, whose corrosion rates are 1.6–2.2 orders of magnitude lower than those of pure-Nb (depending on temperature). An exclusive NbO₂ layer was formed on pure Nb, while heterophasic scales were observed on Nb-Al alloys whose compositions and amounts strongly depended on Al content and temperature. The scales formed on Nb-12.5Al consisted of mostly NbO₂ and minor amounts of Nb₂O₅, NbS2, and -Al₂O₃, while the scales formed on Nb-25Al consisted of mostly Nb₂O₅ and some -Al₂O₃. The scales formed on Nb-75Al consisted of mostly -Al₂O₃ and Nb₃S₄ atT 900°C, and mostly -Al₂O₃ , Nb₃S₄ and some AlNbO₄ at 1000°C. The formation of -Al₂O₃ and Nb₃S₄ resulted in a significant reduction of the corrosion rates.     

Preparation and characteristic of spherical Li3V2(PO4)3

Spherical Li₃V₂(PO₄)₃ was synthesized by using N₂H₄ as reducer. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that single-phase, spherical and well-dispersed Li₃V₂(PO₄)₃ has been successfully synthesized in our experimental process. Electrochemical behaviors have been characterized by charge/discharge measurements. The initial discharge capacities of Li₃V₂(PO₄)₃ were 123 mAh g⁻¹ in the voltage range of 3.0–4.3 V and 132 mAh g⁻¹ in the voltage range of 3.0–4.8 V.     

Effects of K2O-Li2O doping on surface and catalytic properties of Fe2O3/Cr2O3 system

The effects of K₂O and Li₂O-doping (0.5, 0.75 and 1.5 mol%) of Fe₂O₃/Cr₂O₃ system on its surface and the catalytic properties were investigated. Pure and differently doped solids were calcined in air at 400-600 °C. The formula of the un-doped calcined solid was 0.85Fe₂O₃:0.15Cr₂O₃. The techniques employed were TGA, DTA, XRD, N₂ adsorption at −196 °C and catalytic oxidation of CO oxidation by O₂ at 200-300 °C. The results revealed that DTA curves of pure mixed solids consisted of one endothermic peak and two exothermic peaks. Pure and doped mixed solids calcined at 400 °C are amorphous in nature and turned to α-Fe₂O₃ upon heating at 500 and 600 °C. K₂O and Li₂O doping conducted at 500 or 600 °C modified the degree of crystallinity and crystallite size of all phases present which consisted of a mixture of nanocrystalline α- and γ-Fe₂O₃ together with K₂FeO₄ and LiFe₅O₈ phases. However, the heavily Li₂O-doped sample consisted only of LiFe₅O₈ phase. The specific surface area of the system investigated decreased to an extent proportional to the amount of K₂O and Li₂O added. On the other hand, the catalytic activity was found to increase by increasing the amount of K₂O and Li₂O added. The maximum increase in the catalytic activity, expressed as the reaction rate constant (k) measured at 200 °C, attained 30.8% and 26.5% for K₂O and Li₂O doping, respectively. The doping process did not modify the activation energy of the catalyzed reaction but rather increased the concentration of the active sites without changing their energetic nature.     

Alloyed W–(Co,Ni,Fe)–C phases for reaction sintering of hardmetals

It has been shown that W–Co–C phases could dissolve a substantial amount of metals such as V, Cr and Ta, which are known to positively influence the microstructure of hardmetals with respect to uniform grain size distribution and fine grain size. This offers a tool to circumvent the conventional doping of hardmetals with individual carbides. In the present study we used double- and triple-alloyed κ-W₉Co₃C₄ (i.e. κ-(W,V,Cr)₉Co₃C₄ and κ-(W,V,Cr,Ta)₉Co₃C₄) and applied a variety of sintering experiments to obtain WC–Co, WC–(Ti,Ta,Nb)C–Co and WC–(Ti,Ta,Nb)(C,N)–Co hardmetals. We also prepared κ-W₉Fe₃C₄, alloyed κ-W₉Ni₃C₄, and κ-W₉(Fe/Ni)₃C₄, and used the latter for sintering.     

Synthesis of lanthanum carbonate nanoparticles via sonochemical method for preparation of lanthanum hydroxide and lanthanum oxide nanoparticles

Lanthanum carbonate nanoparticles were synthesized from the reaction of lanthanum acetate and Na₂CO₃ under sonication via sonochemical method. Lanthanum hydroxide nanoparticles were prepared by facial hydrothermal processing from the resulted product at 110 °C for 24 h. The role of surfactant, calcination temperature and sonication time were investigated on the morphology and particle size of the products. Products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and Fourier transform infrared (FT-IR) spectra. La₂O₃ nanoparticles were obtained by calcinations of the nanoparticles of lanthanum carbonate at 600 °C.     

锂离子电池正极材料LiNi0.8Co0.15Al0.05O2的制备及电化学性能

首先以AlO2-为铝源,采用三元共沉淀法制备前驱体Ni_(0.8)Co_(0.15)Al_(0.05)(OH)_2。对前驱体进行500℃高温处理,随后与过量的锂盐混合均匀,在氧气气氛下700℃煅烧12 h制得LiNi_(0.8)Co_(0.15)Al_(0.05)O_2(NCA)材料。采用X射线衍射仪(XRD)测试可知,所得的NCA材料呈典型的α-NaFeO_2层状结构,属于R-3m空间群。扫描电子显微镜(SEM)测试显示,NCA为粒径5～6μm的球状颗粒。材料在电流倍率为0.1C下首次放电容量为167.1mAh/g,循环200次以后容量保持率为96.2%。倍率测试表明,0.1、10 C下NCA的容量分别为184.0、112.7 mAh/g,到恢复到0.1 C时,容量仍可达179.7mAh/g,具有比较好的倍率性能。     

Effects of Mo and Al Additions on the Sulfidation Behavior of 310 Stainless Steel

The high-temperature sulfidation behavior of 310stainless steel (310SS) with Mo and Al additions (up to10 at.%) was studied over the temperature range700-900°C in pure-sulfur vapor over the range of 10^-3 to 10^-1 atm. Thecorrosion kinetics followed the parabolic rate law inall cases and the sulfidation rates increased withincreasing temperature and sulfur pressure. Thesulfidation rates decreased with increasing Mo and Al contents and it wasfound that the addition of 10 at.% Mo resulted in themost pronounced reduction among the alloys studied. Thescales formed on 310SS with Mo additions were complex, consisting of an outer layer of ironsulfide (with dissolved Cr), (Fe,Ni)₉S₈, andCr₂S₃/Cr₃S₄(with dissolved Fe), and an inner heterophasic layer ofFe_1-xS,Cr₂S₃/Cr₃S₄,NiCr₂S₄,Fe_1.25Mo₆S_7.7, FeMo₂S₄, andMoS₂. The scales formed on 310SS with Mo andAl additions had a similar mixture as above, except thatAl_0.55Mo₂S₄ was alsoobserved in the inner layer. The formation ofMoS₂ andAl_0.55Mo₂S₄ partly blocked the transport of cations throughthe inner scale, resulting in the reduction of thesulfidation rates compared to 310SS.