Effect of interconnect pre-oxidation on high-temperature wettability and mechanical properties of glass seals in SOFC

Metallic interconnect oxidation has a significant influence on shear strength between interconnect and sealing glass in SOFC stack operation. This is attributed to high-temperature mutual wettability. In this work, the glass having different crystallization kinetics was chosen to evaluate wettability and shear strength on Fe–16Cr alloy, which was heated treated at 750°C for 0, 50, and 100 h, forming oxide scale with a varying rough surface. Visual observation was used to quantify equilibrium contact angles between glass and substrates. The results illustrated that alloy oxidized for 50 h exhibited better wettability and shear strength, implying that thickness and roughness of the oxide scale are critical to enhancing interface joint strength. Long-term testing indicated that thermally stable glass possesses higher joint shear strength and more consistent properties. It was found that precipitated crystalline phases limited improvement of glass wettability, resulting in interfacial delamination of the glass/alloy layer over long-term operation.     

Optimal nanocone geometry for water flow

The pursuit, toward transport efficiency, is significantly necessary for energy conversion, water filtration. However, structure design, aiming at further enhancing nanoconfined water flow, is still lacking. With the motivation to bridge the knowledge gap, a simple yet practical model regarding the nanocone structure design is established. This research demonstrates that nanocone, with desirable opening angle and length, possesses the capacity to achieve the optimal flow behavior. Flow resistance occurring inside nanocones, and that at cone entrance, exit, are considered. Optimal nanocone geometry can be determined based on the minimization of total resistance. Results show that (a) suitable opening angle spans from 10° to 30° over a wide range of nanocone geometry; (b) evident decline tendency of the suitable opening angle toward the increasing surface wettability is captured; and (c) water transport capacity inside optimal nanocone is 4–50 times that within cylindrical nanopores. This article forms a theoretical framework for nanocone design.     

烷基甜菜碱表面活性剂疏水基碳链长度对低渗岩心自发渗吸的影响

为研究烷基甜菜碱亲水基结构相同、疏水基碳链长度不同对渗吸机理的影响,通过开展自发渗吸、接触角和油水界面张力实验,分析在高温、高矿化度、低渗透条件下,烷基甜菜碱疏水基碳链长度对自发渗吸的影响规律。结果表明:随着疏水基碳数由12增至18,4种烷基甜菜碱渗吸采出程度分别为37.8%、39.4%、41.0%和42.1%;渗吸方式均为逆向渗吸,接触角随碳数增加而减小,有利于原油剥离岩心;界面张力随碳数增加而降低,有利于油滴变形流动,共同促进渗吸过程。实验结果满足归一化采出程度模型,对烷基甜菜碱作为渗吸剂在低渗透油田应用具有理论指导意义。     

地下含水层储存氢气的可行性分析

目的氢气的安全、高效储存对清洁能源工业化发展具有重要意义；地下含水层分布广泛、储存潜力巨大,是安全、高效地下储存氢气的潜在体。对地下含水层储存氢气的可行性进行了分析。 方法通过调研国内外关于地下含水层储存氢气的文献,在明确氢气的物理化学性质对含水层影响的基础上,分析了现有氢气地下储存的案例,探索了多种因素对含水层储存氢气的影响。 结果碳酸盐和硫酸盐胶结物含量低的砂岩以及盖层不含方解石的地质条件更适合氢气地下储存,在富有黏土矿物的储层中储存氢气是有利的；氢气地下储存应考虑微生物的影响；二氧化碳和氮气都可以作为缓冲气体,在中国进行“双碳”目标重大战略决策的当下,应该着重进行二氧化碳作为缓冲气体的研究。 结论目前,没有地下含水层储存纯氢的实例,但是相关的数值模拟研究和影响因素分析论证了含水层中储存氢气的可行性。      

载体对甲维盐固体纳米制剂的性能影响

为了研究载体对农药固体纳米制剂理化性能的影响及其选择原则，采用自乳化-载体固化法制备了7种不同载体的甲氨基阿维菌素苯甲酸盐（甲维盐）固体纳米分散体。比较了载体粉末粒度、溶解度、比表面积及形貌间的差异性，揭示了不同载体对甲维盐固体纳米分散体粒径、分散度、界面电荷、pH、晶型及叶面润湿性的影响。结果表明，农药固体纳米分散体中载体的理化性质及结构对纳米制剂的粒度、分散性、界面性质及晶型具有显著影响。苯甲酸钠为甲维盐固体纳米分散体的优良载体，载药粒子的平均粒径为22 nm，PDI为0.358。     

预烘烤对镀锡板表面膜层和润湿性的影响

目的 提高镀锡板与涂料匹配性，研究预烘烤消除缩孔对镀锡板表面膜层和润湿性能的影响。方法 采用计时电位曲线、X光电子能谱仪、热重差热测试及表面接触角方法，分别评价烘烤处理前后的镀锡板表面钝化膜、氧化膜成分含量变化，并通过表面能对表面润湿性变化进行分析。结果 120 ℃烘烤不同时间下，钝化膜铬含量由4.30 μg/cm²增至5.16 μg/cm²，膜层中的Cr(OH)3/Cr2O3含量比例显著下降，使Cr(OH)3脱水缩合生成电活性的Cr2O3被检出。氧化膜含量(库伦法计算)由1.5 mC/cm²以上降至0.6 mC/cm²左右，其组成进一步被氧化生成SnO2，无法被阴极还原，降低了可被检出的氧化膜含量。水接触角由86°快速降至65°左右稳定，表面能值由37.5 mN/m最高增至50 mN/m，说明烘烤处理大幅提高了材料表面被水极性介质的润湿作用。结论 通过镀锡板涂膜前预烘烤处理，改变了镀锡板表面钝化膜和氧化膜组成以及含量比例，降低了水接触角，提高了表面能值，增强了材料对涂料表面张力适配范围，有利于漆膜稳定铺展，为涂料端配方优化，实现镀锡板缩孔控制提供了技术方向。     

Aerobic oxidation of benzyl alcohol in a slug flow microreactor: Influence of liquid film wetting on mass transfer

Homogeneous Co/Mn/Br catalyzed aerobic oxidation of benzyl alcohol in acetic acid to benzaldehyde was performed in polytetrafluoroethylene microreactors operated under slug flow at temperatures up to 150°C and pressures up to 5 bar. Depending on the bubble velocity and length, a wetted or dewetted slug flow was observed, characterized typically by a complete or partially wetting liquid film around the bubble body. The latter flow suffered from a limited interfacial area for mass transfer. Experiments at temperatures up to ca. 90°C were under kinetic control given no product yield difference under wetted and dewetted slug flows and were used to establish a simplified kinetic expression (first order in benzyl alcohol and zero order in oxygen). This allows to develop a mass transfer model combined with an instantaneous reaction regime that well described the experimental results at higher temperatures where mass transfer was limiting in the dewetted slug flow.     

Influence of water addition on the modification of polyethylene surface by nitrogen atmospheric pressure plasma jet

Polyethylene (PE) has many excellent material properties (low density, high flexibility, good chemical resistance, etc.), and is widely used in industrial and medical fields. However, the practical applications of PE are sometimes limited due to its poor wettability. In this article, we employ pure nitrogen atmospheric pressure plasma jet (APPJ) and N₂-H₂O APPJ to hydrophilize PE surfaces. Wettability, time stability, chemical composition, micromorphology, and mechanical properties of the treated surfaces are investigated by contact angle measurement, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and electric digital display push–pull machine. The pure nitrogen APPJ can hydrophilize PE surfaces without inducing obvious microstructure changes, and relatively better wettability (water contact angle = 13°) could thereby be achieved. On the other hand, the N₂-H₂O APPJ creates micro/nanoscale pores on the treated hydrophilic surfaces, contributing to the better time stability and lower tensile strength. The results reported here clearly demonstrate the great potential of nitrogen APPJs with different water mixing ratios in controlling surface wettability and microstructures of polymer surfaces. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47136.     

Property enhancement in polypropylene ternary blend nanocomposites via a novel poly(ethylene oxide)‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene toughener–compatibilizer system

Synthesis and characterization of a novel toughener–compatibilizer for polypropylene (PP)–montmorillonite (MMT) nanocomposites were conducted to provide enhanced mechanical and thermal properties. Poly(ethylene oxide) (PEO) blocks were synthetically grafted onto maleic anhydride‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene (SEBS‐g‐MA). Special attention was paid to emphasize the effect of PEO‐grafted SEBS (SEBS‐g‐PEO) against SEBS‐g‐MA on morphology, static/dynamic mechanical properties and surface hydrophilicity of the resultant blends and nanocomposites. It was found that the silicate layers of neat MMT are well separated by PEO chains chemically bonded to nonpolar SEBS polymer without needing any organophilic modification of the clay as confirmed by X‐ray diffraction and transmission electron microscopy analyses. From scanning electron microscopy analyses, elastomeric domains interacting with MMT layers via PEO sites were found to be distributed in the PP matrix with higher number and smaller sizes than the corresponding blend. As a benefit of PEO grafting, SEBS‐g‐PEO‐containing nanocomposite exhibited not only higher toughness/impact strength but also increased creep recovery, as compared to corresponding SEBS‐g‐MA‐containing nanocomposite and neat PP. The damping parameter of the same nanocomposite was also found to be high in a broad range of temperatures as another advantage of the SEBS‐g‐PEO toughener–compatibilizer. The water contact angles of the blends and nanocomposites were found to be lower than that of neat hydrophobic PP which is desirable for finishing processes such as dyeing and coating. © 2018 Society of Chemical Industry