共溶剂对溶胶-凝胶法制备PVA/SiO2杂化材料的影响

通过溶胶-凝胶法(Sol-Gel)制得了透明PVA/SiO2杂化材料,重点研究了共溶剂的选择对杂化材料相分离的影响。采用扫描电子显微镜和能谱对使用不同共溶剂制备PVA/SiO2杂化材料体系中产生的沉淀物进行了分析研究。结果表明,在溶胶-凝胶法制备PVA/SiO2杂化材料的PVA-TEOS体系中,在以乙醇、四氢呋喃和乙醛为有机共溶剂的情况下,如果pH值控制不当,溶胶过程中会有絮状沉淀物出现。不使用有机共溶剂可合成具有良好透明性、体积收缩小、没有相分离的PVA/SiO2杂化材料。     

疏水型多孔PVA/SiO2有机无机杂化材料的研究

以正硅酸乙酯(TEOS)、甲基三乙氧基硅烷(MTES)、聚乙烯醇(PVA)为原料，基于溶胶凝胶工艺制备出疏水型多孔PVA／SiO2有机无机杂化材料。杂化材料内部的硅氧链与PVA链相互交织，形成杂化网络结构，具有增强增韧的效果。杂化材料在热处理过程中，小分子逸出产生的微孔和材料表面面外的甲基，赋予了材料的透气疏水性能，可用于制备性能优良的环保型包装薄膜、农用地膜等功能复合材料。     

PVA/SiO2杂化材料的制备及表征

采用甲醛、乙醛及正丁醛作为改性剂,分别对 PVA进行改性,研究了改性PVA与TEOS及KH-560制备透明防雾涂层的工艺过程及涂层的性能. 结果表明,综合性能AMPVA＞FMPVA＞n-BMPVA,nBMPVA难以形成透明涂层;通过FT-IR分析证明涂层中有Si-O-Si生成;并讨论了涂层TGA曲线与涂层的透明性的关系.     

3D成型SiO_2/PVA水凝胶支架的摩擦行为

利用3D成型技术,通过先成型后冷冻交联2步法制备不同孔隙率的SiO_2/聚乙烯醇(PVA)水凝胶支架,研究了SiO_2/PVA水凝胶支架的重复摩擦行为,分析了SiO_2/PVA水凝胶支架的摩擦原理。结果表明:SiO_2/PVA水凝胶支架能够保持三维贯通的立体结构,最大孔隙率可达42.3%。低摩擦速率(10-6~10-3 m/s)下,SiO_2/PVA水凝胶支架摩擦力稍高于块体SiO_2/PVA水凝胶,且随孔隙率的提高而稍有降低;而高摩擦速率(10-2~1m/s)下,SiO_2/PVA水凝胶支架和块体SiO_2/PVA水凝胶的摩擦力相近,孔隙率对支架摩擦力影响不明显。低正压力载荷(0.3kPa)下,SiO_2/PVA水凝胶支架重复摩擦性优于块体SiO_2/PVA水凝胶,这与支架结构能保持稳定的水润滑层相关。     

The preparation and mechanical properties of novel PVA/SiO2 film

The aim of this work is the evaluation of the mechanical properties of composite PVA/SiO₂. A powder impregnation process with integrated inline continuous plasma of SiO₂ was used to produce PVA/SiO₂ composite. PVA/SiO₂ composite was processed into test laminates by compression mounding and the interface-dominated composite properties were studied. When compared to PVA, the mechanical properties of PVA/SiO₂ were significantly increased, such as tensile strength, tensile modulus and elongation at break, and the damping capacity of PVA/SiO₂ film increased with increasing ratio of SiO₂.     

PVA对SiO2减反膜表面结构的影响

以正硅酸乙酯(TEOS)为有机硅源,乙醇为溶剂,NH3.H2O为催化剂,采用溶胶-凝胶技术,加入PVA(聚乙烯醇)添加剂,在玻璃上用旋涂法制备减反膜,并对其进行热处理;分别采用椭偏仪和扫描电镜对所制备减反膜的结构、物性进行研究,研究PVA添加剂对减反膜结构、折射率的影响。结果表明:适量的PVA添加剂可以控制SiO2太阳电池减反膜的开裂。     

PVA/SiO2杂化纤维的制备与表征

采用溶胶凝胶法制备了不同SiO2含量的PVA/SiO2杂化溶胶,通过拉丝得到杂化纤维。对溶胶的可纺性和杂化纤维的性能进行了研究。结果表明,SiO2溶胶与PVA/SiO2杂化溶胶在反应过程中的黏度变化规律相似,黏度均存在三个变化区间,随PVA含量的增加,杂化溶胶的可纺性能改善。FT-IR表明,杂化纤维中PVA与SiO2之间形成了化学键结合;XRD、DSC和光学显微分析表明,杂化使PVA结晶能力明显降低;热失重和耐溶剂研究表明,PVA与SiO2之间的化学键结合使杂化纤维具有良好的耐热性能。     

原位合成法二氧化硅/硅钨酸改性聚乙烯醇质子交换膜的研制

以聚乙烯醇(PVA)为基体,利用原位合成法制备了二氧化硅(SiO2)和硅钨酸(SiWA)微粒在PVA基质中均匀分布的二氧化硅/硅钨酸改性聚乙烯醇(SiO2/SiWA-m-PVA)质子交换膜,利用扫描电镜(SEM)和热重分析仪(TG)分别对膜的形貌及热稳定性进行了表征,四氯化硅与钨酸钠摩尔比对SiO2/SiWA-m-PVA质子交换膜的质子导电性能、阻醇性能的影响.结果表明,四氯化硅与钨酸钠摩尔比为1∶1时,原位合成的二氧化硅和硅钨酸在质子交换膜中分散均匀,在温度低于100℃时SiO2/SiWA-m-PVA膜保水性能好;室温质子电导率为1.48×10-2 S/cm,甲醇渗透率为1.37×10-7 cm2/s,比相同条件下Nafion117膜甲醇渗透率低一个数量级,应用于直接甲醇燃料电池单电池能量密度可达11.82 mW/cm2.     

改性纳米SiO_2/PVA复合纤维的制备及重金属离子吸附性能

通过静电纺丝技术制备酰肟化功能改性的纳米SiO_2/聚乙烯醇(SiO_2/PVA)复合纤维膜。采用SEM、FTIR、DSC和TGA进行表征分析;考察了在水溶液中随pH值和接触时间的变化纤维膜对金属离子吸附效果的影响。研究表明,在pH=6的条件下,纳米纤维对金属离子的吸附最佳,对Cu2+、Ni 2+金属离子的最大吸附量分别为143.7mg/g和125.1mg/g,平衡吸附时间为240min。在纤维膜吸附的前50min内,SiO_2/PVA纤维膜对Cu2+和Ni 2+金属离子的吸附量为126.8mg/g和109.8mg/g,吸附率分别为90.18%和89.92%。通过吸附等温线和吸附方程考察SiO_2/PVA纤维对Cu2+和Ni 2+金属离子的吸附行为。结果显示,复合纤维对两种金属离子的吸附满足拟二级动力学方程,热力学分析表明,吸附过程符合Langmuir单层吸附。使用酸处理纤维膜进行再生吸附试验,发现循环4次试验后,吸附效率达到53%,结果说明复合纤维膜可作为可再生金属离子吸附材料。     

SiO2f/SiO2-BN复合材料的制备及其性能

以石英纤维预制件和硅溶胶为原料,采用溶胶-凝胶法制备了SiO2f/SiO2复合材料,在此基础上用尿素法制备了SiO2f/SiO2-BN复合材料,并对其力学性能和介电性能进行了测试.结果表明,随着工艺循环次数的不断增加,复合材料的密度随之提高,但增长速度逐渐减慢.三次循环后,SiO2f/SiO2-BN复合材料密度达1.8...     

聚丙烯酸酯-聚乙烯醇-纳米SiO_2超亲水涂层

通过水热法制备了具有交联结构的聚丙烯酸酯(PAAS)-聚乙烯醇(PVA)-纳米SiO2有机无机复合乳液,并将该乳液通过提拉在玻璃基底和PET膜上构建了性能稳定、透明的亲水涂层。研究了乳液中纳米颗粒掺入量对涂层表面形貌、润湿性和透光率的影响,结果表明,随着纳米粒子掺入量的增加,涂层亲水性随之增大,而透过率随之下降。当PVA含量为0.25wt%,PAAS、PVA和SiO2的质量比为1∶2.5∶10时,涂层亲水性长效稳定,一个月时间内接触角保持在5°左右,在500~760nm波长范围内透过率超过78.68%,硬度达到HB。常温聚丙烯酸酯-聚乙烯醇-纳米SiO2亲水涂层具有稳定的耐水性和良好的抗结霜和快速除霜性能。     

聚乙烯醇/纳米纤维素/聚乙烯醇的层层自组装及表征

采用基于氢键驱动力的层层(LBL)自组装技术制备聚乙烯醇(PVA)/纳米纤维素(NCC)/聚乙烯醇复合膜。通过衰减全反射红外(ATR-IR)、扫描电子显微镜(SEM)和X射线衍射(XRD)分析,验证了该复合膜中NCC和PVA的单相分布情况,NCC晶格定向排列状态,以及NCC作为夹层的结构,并提出了机理假设论证了该结构复合膜的形成过程;通过拉伸强度、透光率和热稳定性测量,表明LBL自组装制备的PVA/NCC/PVA复合膜具有高的拉伸强度、高的透光率和较高的热稳定性,其中拉伸强度较PVA膜提高了46.1%,透光率提高了5.44%,热分解温度提高了13.2℃,表明该法制备的PVA/NCC/PVA复合膜是一种良好的功能性薄膜。     

High-reflectivity HfO2/SiO2 ultraviolet mirrors

High-reflectivity dense multilayer coatings were produced for the ultraviolet spectral region. Thin-film single layers and UV mirrors were deposited by ion plating and plasma ion-assisted deposition high-energetic technologies. Optical characterizations of HfO2 and SiO2 single layers are made. The optical constants obtained for these two materials are presented. HfO2 and SiO2 mirrors with a reflectance of approximately 99% near 250 nm are reported.     

TiNx/SiO2/Ag/SiO2低辐射膜耐H2S气体的腐蚀性能

为了提高玻璃片上SiO2/Ag/SiO2复合膜的耐腐蚀性能,用磁控溅射法在其上制备了TiNx薄膜.采用X射线衍射(XRD)、扫描隧道显微镜(STM)研究了TiNx薄膜的结构及表面形貌;参照GB/T 5137.3-2002电子产品硫化氢腐蚀的检验方法研究了TiNx/SiO2/Ag/SiO2低辐射膜耐H2S气体的腐蚀性能....     

Numerical study on optical properties of Ag/SiO2SiO2/Ag sandwich nanocrescents substrate

A novel structure of a metal/dielectric/metal (Ag/SiO₂SiO₂/Ag) sandwich nanocrescent has been proposed and studied. We make a detailed numerical analysis on the extinction efficiency and LSPR property of the sandwich nanocrescent by using the finite difference time domain (FDTD) method. It clearly demonstrates that a comparable field enhancement can be achieved by varying the thickness of the SiO₂SiO₂ layer at different incident polarizations. Excited in the Y-polarization, the maximum electric field enhancement factor reaches 600 at the peak wavelength 1108.9?nm, which is six times higher than previous reported single layer nanocrescent. The refractive index sensitivity of this new sandwich nanocrescent is 375.5?nm/RIU (refractive index unit). The structure is shown to produce a high local field enhancement as well as wide plasmon resonance tunabilities. Besides, compared with adjusting the shape and size of the single layer nanocrescent structure, it is much more convenient and easier to change the thickness of the sandwich nanocrescent. Due to its excellent properties, this structure is very suitable for LSPR and SERS nanosensing substrate.     

Optical properties of the Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings

Investigations of bilayer and trilayer Al₂O₃/SiO₂ and Al₂O₃/HfO₂/SiO₂ antireflective coatings are presented in this paper. The oxide films were deposited on a heated quartz glass by e-gun evaporation in a vacuum of 5 × 10^?3 [Pa] in the presence of oxygen. Depositions were performed at three different temperatures of the substrates: 100 °C, 200 °C and 300 °C. The coatings were deposited onto optical quartz glass (Corning HPFS). The thickness and deposition rate were controlled with Inficon XTC/2 thickness measuring system. Deposition rate was equal to 0.6 nm/s for Al₂O₃, 0.6 nm ? 0.8 nm/s for HfO₂ and 0.6 nm/s for SiO₂. Simulations leading to optimization of the thin film thickness and the experimental results of optical measurements, which were carried out during and after the deposition process, have been presented. The optical thickness values, obtained from the measurements performed during the deposition process were as follows: 78 nm/78 nm for Al₂O₃/SiO₂ and 78 nm/156 nm/78 nm for Al₂O₃/HfO₂/SiO₂. The results were then checked by ellipsometric technique. Reflectance of the films depended on the substrate temperature during the deposition process. Starting from 240 nm to the beginning of visible region, the average reflectance of the trilayer system was below 1 % and for the bilayer, minima of the reflectance were equal to 1.6 %, 1.15 % and 0.8 % for deposition temperatures of 100 °C, 200 °C and 300 °C, respectively.     

Effects of different types of PVA on the properties of the nano-TiO2/PVA

用硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH550）对纳米TiO2进行改性,将不同比例的聚乙烯醇（17-88与17-99）相混合制成胶液,再采用直接共混法制备了纳米TiO2/聚乙烯醇（PVA）复合材料,并流延成膜。通过自制透水仪、扫描电镜、热失重分析、拉伸强度、耐水性能以及透明性对纳米TiO2/PVA复合膜进行表征,探讨不同含量的PVA 17-88对复合膜的性能影响。结果表明,PVA 17-88的质量分数为30%,纳米TiO2/PVA膜厚度控制在25～30μm,透水量较大,拉伸强度达到28.72MPa,耐水性能最佳。     

采用Ag-Cu-Ti钎料真空钎焊SiO2f/SiO2复合陶瓷与C/C复合材料

分别在880℃/10min和880℃/60min规范下,采用Ag-Cu-Ti活性钎料实现了SiO2f/SiO2复合陶瓷与C/C复合材料的真空钎焊连接,通过电子探针(EPMA)、能谱仪(XEDS)和X射线衍射仪(XRD)分析了接头微观组织,室温下测试了接头的抗剪强度。结果表明:两种规范下所得接头界面结合良好,接头中靠近两侧母材均形成了一层扩散反应层,钎缝基体主要由均匀的共晶组织组成。880℃/10min规范下钎焊接头界面产物依次为:SiO2f/SiO2→Ti4O7→Ti5Si4+Cu(s,s)+Ag-Cu共晶合金→TiC→C/C;对于880℃/60min规范下的接头,界面组织结构与保温10min的接头基本类似,但是不存在Cu(s,s),并且接头反应层明显增厚。880℃/60min条件下所得钎焊接头剪切强度平均值为16.6MPa。     

水浸腐蚀对SiO_2/Ag/SiO_2复合膜光学特性的影响

用蒸镀法制备了SiO2 Ag SiO2 复合膜 ,探讨了水浸腐蚀和薄膜厚度对该复合膜光学特性的影响。试验结果表明 :适当增加复合膜中SiO2 膜层的厚度不但可以提高SiO2 Ag SiO2 复合膜可见光的透光率 ,而且可以相对有效地防止复合膜进一步被氧化 ,提高SiO2 Ag SiO2 复合膜的抗水浸腐蚀性能     

Characteristics of SiO2/Si3N4/SiO2 stacked-gate dielectrics obtained via atomic-layer deposition

An interpoly-stacked dielectric film with a SiO2/Si3N4/SiO2/Si (ONO) structure was prepared via the atomic-layer deposition method. The multilayer structure of the ONO film with triple interfaces was investigated via medium-energy ion scattering (MEIS). A few defects in the interface layer of the ONO structure were detected. From the X-ray photoelectron spectroscopy (XPS) results, it was presumed that the interface layer with defects in the MEIS result is due to the formation of an oxynitride layer on the unstable and rougher Si3N4 layer via. By measuring the I-V characteristics, the leakage current density and breakdown field of the ONO film were determined to be 3.4 x 10(-9) A/cm2 and 10.86 MV/cm, respectively. By estimation the C-V curve, the flat band (V(FB)) of the ONO film shifted to a negative voltage (-1.14 V), the dielectric constant (K(ONO)) of the ONO film was 5.79, and the effective interface-trapped charge density of the ONO film was about 4.96 x 10(11)/cm2.