ZnO/TiO_2核壳异质结的制备及其光电性能研究

采用硝酸锌/六次甲基四胺溶液体系,首先利用水热法在ITO导电玻璃基片上制备ZnO纳米棒,然后,再利用溶胶-凝胶法,并结合浸渍-提拉工艺在附有ZnO纳米棒的ITO导电玻璃基片上制得ZnO/TiO2核壳异质结,考察了TiO2溶胶的浓度以及拉膜次数对异质结形貌及其性能的影响.结果表明：TiO2溶胶的浓度和拉膜次数都对异质结的形貌有显著的影响,TiO2在ZnO纳米棒表面的附着量随TiO2溶胶的增加而增大.另外,拉膜次数的增多也会增加TiO2在ZnO纳米棒表面的附着量,在适宜的附着量下会得到形貌较好的ZnO/TiO2核壳异质结.基于ZnO/TiO2核壳异质结的设备,其光电转化效率提高了50.79%     

Dip-Coating of YBa2Cu3O7?δ and YBa2Cu3O7?δ-Ag Films on Polycrystalline Rare-Earth Barium Niobate Substrates

Dip-coating and partial melting technique have been used to fabricate high quality superconducting YBa₂Cu₃O_7– and YBa₂Cu₃O_7–-Ag thick films with T _c(0)=92 K on polycrystalline REBa₂NbO₆ (RE=Pr, Nd, Sm, and Eu) substrates. The superconducting films showed excellent adhesion to the REBa₂NbO₆ substrate. The effect of Ag addition in YBa₂Cu₃O_7– on the current density, microstructure, and crystal orientation of the superconducting films developed on the above substrates have been discussed in detail. Dip-coating technique was found to be one of the easiest method for obtaining good quality superconducting YBa₂Cu₃O_7– thick films with thickness as low as 3 m even on polycrystalline substrates.     

改进浸浆法制备氧化钛/多孔钛复合微滤膜

金属陶瓷复合膜以多孔金属为载体、多孔陶瓷为活性分离层,结合了陶瓷膜和金属膜的优点,具有良好的工业应用前景。采用改进浸浆法制备氧化钛/多孔钛复合微滤膜。将氧化钛粉体分散到氧化钛溶胶中作为制膜液,以提高制膜液在多孔金属支撑体表面的润湿性.结果表明,相同温度下溶胶的表面张力远小于水的表面张力,溶胶分散制膜液的表面张力也远小于水分散制膜液的表面张力.由此明显地改变了制膜液和支撑体的润湿性能,从而可以制备得到连续完整的膜层.由于溶胶粒子对粒径较大的氧化钛颗粒的烧结促进作用,使得膜层可以在较低的温度下烧结.在850℃下烧结的膜层平均孔径为0.31μm,且分布较窄.膜层表面完整无缺陷,与支撑体结合情况良好,膜层厚度约为17μm.膜层N2渗透通量为6.6×105L/(m2.h)(0.1 MPa).     

Preparation and Performance of the Sm0.2Ce0.8O1.9-x Single Buffer Layer Fabricated with Dip-Coating

在双轴织构的Ni-5％W合金基带上,采用高分子辅助化学溶液沉积法通过提拉涂敷法,制备了厚度达250 nm的Sm0.2Ce0.8O1.9(SCO)外延织构单层缓冲层.通过严格控制前驱溶液的浓度、提拉速度、成相温度和热处理时间,所获的SCO单层缓冲层涂层平整、无微裂纹、且具有较强的(200)c轴外延织构.在其他条件假设不变的情况下,主要研究不同提拉速度对SCO缓冲层薄膜性能的影响.在此基础上,采用化学溶液法在SCO/NiW缓冲层上制备了YBCO超导层,其具有高度的双轴织构和均匀的表面形貌.结果表明:用提拉法获得的SCO单层缓冲层在具有适度的厚度下,仍然具有很好的织构传递特性,为低层本制造YBCO涂层导体长带提供了一条可靠的路线.     

浸浆制备过程中载体微结构及涂膜工艺参数对膜厚度的影响

以“浸浆”成型法制备α-Al₂O₃陶瓷膜过程为研究对象,提出以载体的纯水渗透性能关联载体的微结构参数来预测载体对膜厚度的总体影响的方法.实验考察了涂膜工艺参数（浸浆时间和流动速度）以及载体纯水渗透性能对膜厚度的影响.结果表明：浸浆时间越长,所形成的膜层厚度越厚且膜厚度与浸浆时间的1/2次方呈正比.而当载体孔道被完全充满后,膜厚度随着时间延长而下降;在制膜液进入载体和脱离载体过程中,膜厚度首先随着制膜液的流动速度的2/3次方线性增长,当流动速度超过一定值后,膜厚度不再变化;载体的渗透性能越优越,越有利于膜厚的形成,且膜厚度与载体的纯水渗透通量呈线性关系.     

TiO_2纳米管/介孔SiO_2复合膜的制备及生物活性研究

以表面构筑了TiO2纳米管阵列的金属钛为基底,采用溶胶-凝胶工艺和浸渍-提拉技术涂覆介孔SiO2薄膜,构建了TiO2纳米管/介孔SiO2复合膜。利用SAXRD、FTIR、HRTEM和FESEM等表征样品的结构和微观形貌。研究表明,在高度有序、规整排列的TiO2纳米管阵列基底上,利用溶胶-凝胶工艺和浸渍-提拉技术涂覆有六方相介孔SiO2薄膜的复合膜具有良好的生物活性。     

纯钛表面立方介孔SiO2薄膜诱导沉积碳磷灰石层

采用浸渍-提拉法在预处理纯钛表面制备立方介孔SiO₂薄膜, 通过评价体外诱导类骨碳磷灰石层形成能力研究其生物活性。利用小角X射线衍射、傅立叶变换红外光谱、N₂吸附、电镜和能谱等测试技术对模板剂去除前后、模拟体液浸泡前后介孔薄膜结构、组成与形貌进行了研究; 利用固体表面Zeta电位仪研究薄膜表面荷电性质。结果表明, 介孔薄膜具有三维立方介孔结构, 在模拟体液(1.5SBF)中浸泡14 d即能诱导碳磷灰石层在其表面沉积, 显示出良好的生物活性。介孔薄膜独特的孔道结构以及孔表面Si-OH在体液中呈负电性对其生物活性起关键作用。     

Effects of dip-coated BN interphase on mechanical properties of SiCf/SiC composites prepared by CVI process

BN interphase was successfully synthesized on SiC fiber fabrics by dip-coating process using boric acid and urea as precursors under N₂ atmosphere. The morphology of BN interphase was observed by SEM, and the structure was characterized by XRD and FT-IR spectra. The SiC_f/SiC composites with dip-coated BN interphase were fabricated by chemical vapor infiltration (CVI) process, and the effects of BN interphase on the mechanical properties of composites were investigated. The results show that the SiC fibers are fully covered by BN interphase with smooth surface and turbostratic structure (t-BN), and the thickness is about 0.4 μm. The flexural strengths of SiC_f/SiC composites with and without BN interphase are about 180 and 95 MPa, respectively. Compared with the as-received SiC_f/SiC composites, the composites with BN interphase exhibit an obvious toughened fracture behavior. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in protecting the fibers from chemical attack during matrix infiltration and weakening interfacial bonding, which can improve the mechanical properties of SiC_f/SiC composites remarkably.     

Uniform coating of TiO2 nanoparticles using biotemplates for photocatalytic wastewater treatment

Immobilization of TiO₂ particles over substrates like glass can facilitate the separation after photocatalytic runs. Photocatalytic activity of TiO₂ coatings is related to its morphology, crystallography, optical properties and adherence of the coating. Biotemplates, including animal-based and herbal-based templates are inexpensive, biocompatible and abundant and can control the quality of TiO₂ coating. In this study the effects of biotemplates such as agar, gelatin, and starch on the physiochemical properties of TiO₂ coatings were investigated. Synthesized coatings were characterized by XRD, BET, FESEM, TEM, FTIR, EDX, and UV-Vis DRS analyses. The results showed that using biotemplates reduces the TiO₂ crystallite size. Template-free TiO₂ had 30 nm crystallite size, but using templates like agar decreased the size to 18 nm. Moreover, the addition of biotemplates decreased the thickness of TiO₂ coatings compared to template free coating. And the use of biotemplates also limits the pore size distribution and increases BET surface area. According to EDX, TiO₂ coating with agar indicated a uniform Ti distribution and crack-free homogenous morphology. TEM analysis of agar-templated TiO₂ film showed a uniform morphology of TiO₂ particles with average particle size of 20 nm. The UV-Vis DRS also confirmed a reduction in the band gap of TiO₂ after the introduction of biotemplates. The study of the photocatalytic performance of samples showed that agar-templated TiO₂ coating was able to remove 62.4% of methylene blue, while the coatings synthesized with gelatin and starch were just able to remove 42.77% and 35%, respectively. The TiO₂ coating with agar was studied at different pH values and different initial methylene blue concentrations as well. The stability test of agar-templated TiO₂ coating after four runs indicated just 5% of activity lost.     

镁合金表面可降解涂层的制备及其性能

目的 研究生物医用镁合金表面可降解涂层的制备，并对其制备条件、防腐蚀性能，体外降解性、细胞毒性等进行表征。方法 首先合成功能单体7-(2-甲基丙烯酰氧基乙氧基)-4-甲基香豆素(MAC)和2-亚甲基-1,3-二氧杂环庚烷(MDO)，选择乙酸乙烯酯(VAc)作为共聚单体，通过自由基开环聚合合成可降解聚合物P(MAC-VAc-MDO)(PMVO)。将PMVO溶于二氯甲烷中并利用浸涂法在AZ31镁合金表面制备可降解涂层，探究不同制备条件(不同浸涂次数、不同聚合物浓度和不同环境温度)对涂层的膜厚、单位面积膜重以及水接触角的影响，并选择最佳涂层制备条件。采用动电位极化曲线测试对涂层的防腐蚀性能进行表征，可降解涂层的体外降解性和细胞毒性通过模拟体外降解实验和细胞实验进行表征。结果 当浸涂次数为3次、聚合物质量浓度为30 mg/mL、环境温度为40 ℃时，浸涂法制备的涂层均匀致密，此时该涂层具有良好的防腐蚀性能，模拟体外降解实验证明涂层样品浸泡后的pH和镁离子浓度与裸镁相比均有所下降，浸提液细胞毒性实验证明涂层的降解产物无毒。结论 通过自由基开环聚合成功制备聚合物PMVO，并通过浸涂法制备镁合金表面可降解涂层，通过实验证明最佳条件下制备的涂层具有良好的防腐蚀性能、生物可降解性以及细胞毒性。