Sealing behaviour of glass-based composites for oxygen transport membranes

In this study, seven different filler materials in different proportions were added to a Ba-Ca-Si glass matrix “H” to investigate new sealant with higher thermal expansion coefficient (CTE) value and good sealing performance for application in oxygen transport membrane (OTM). SrTi_0.75Fe_0.25O_3-δ (STF25) was used as an OTM, and the sealing partners were ferritic steel Aluchrom and pre-oxidized Aluchrom. Compatibility tests were carried out to investigate the feasibility of the composites. Higher CTE values were found in dilatometer tests on composite samples by adding 40 wt% Ag (HAg40) and 30 wt% Ni-Cr (HNC30). Gas-tightness measurements of sandwiched samples produced appropriate helium leakage rates in the range of 10^?6 mbar·l·s^?1. Sealing behaviour of sealants HAg40 and HNC30 were investigated by joining STF25 and as-delivered/pre-oxidized Aluchrom together. Scanning electron microscopy (SEM) on cross-sections of the joints revealed a homogeneous microstructure and good adherence of the glass sealants to support metals and STF25.     

PCB dry and wet weather concentration and load comparisons in Houston-area urban channels

All 209 PCB congeners are quantified in water in both dry and wet weather urban flows in Houston, Texas, USA. Total water PCBs ranged from 0.82 to 9.4 ng/L in wet weather and 0.46 to 9.0 ng/L in dry. Wet weather loads were 8.2 times higher (by median) than dry weather with some increases of over 100-fold. The majority of the PCB load was in the dissolved fraction in dry weather while it was in the suspended fraction in wet weather. Dissolved PCB loads were correlated with rain intensity and highly developed land area, and a multiple linear regression (MLR) equation was developed to quantify these correlations. PCA generated five PCB components with nearly all positive loadings. They were interpreted as DOC-associated A1248, wet weather primarily suspended fraction A1254/A1260 likely from building sealants, truly dissolved-associated wastewater dechlorination, watershed-sourced PCB 11, and monochlorinated PCBs (likely connected to a different state or source of dechlorination). The PCB 11 component was statistically higher in wet versus dry weather when no other component showed such clear distinctions. Hierarchical cluster analysis (HCA) did not always group dry and wet weather samples from the same location together illustrating the different congener composition that often exists between dry and wet conditions. Four wet weather samples from high percentage developed land (> 90%) watersheds had nearly the same fingerprint suggesting a generic “urban” signature in runoff, which in this case was caused by residual A1254/A1260 PCB stocks and currently produced PCB 11 in consumer goods.     

中空玻璃用弹性密封胶性能及其应用

针对中空玻璃用弹性密封胶的性能、应用知识以及中空玻璃制作、安装使用的相关应用问题作了分析介绍。     

Morphology of sealant/enamel interface after surface treatment with bioactive glass

The purpose of this study was to analyze, by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), the morphology of sealant/enamel interface after surface treatment with Biosilicate. Before pits and fissures sealing, the occlusal surfaces of 10 sound human molars were sectioned perpendicularly at the fissures in order to obtain three slices for each tooth. Slices were randomly assigned into three groups (n = 10) according to sealing protocol: Group 1‐ Acid etching + Biosilicate + glass ionomer‐based sealant (Clinpro XT Varnish, 3M ESPE); Group 2‐ Acid etching + glass ionomer‐based sealant (Clinpro XT Varnish, 3M ESPE); Group 3‐ No sealing. All slices were subjected to thermal cycling (5,000 cycles; 5–55°C; dwell time: 30s). Half of the slices from each group (n = 5) were analyzed by CLSM and the other half by SEM. Groups 1 and 2 were also submitted to EDS analysis and their data were evaluated by Two‐Way ANOVA e Tukey's test (α=5%). EDS data analysis showed higher amounts of silicon (Si) ions than calcium (Ca) ions in Group 1 (P < 0.05); Group 2 presented higher amounts (P < 0.05) of Ca ions than Si ions. It may be concluded that the use of Biosilicate for surface treatment did not affect the morphology of glass ionomer‐based sealant/enamel interfaces. Microsc. Res. Tech. 78:1062–1068, 2015. © 2015 Wiley Periodicals, Inc.     

封孔处理对等离子喷涂Cr2O3-8TiO2涂层耐腐蚀性能的影响

为了提高等离子喷涂陶瓷涂层的耐腐蚀性能,扩大其应用范围,以环氧树脂和有机硅树脂为封孔剂对等离子喷涂Cr2O3-8TiO2涂层进行了封孔处理,采用盐雾腐蚀和电化学腐蚀方法对封孔涂层和未封孔涂层的耐腐蚀性能进行研究,使用扫描电镜/能谱仪(SEM/EDS)、光学显微镜(OM)观察了腐蚀前后涂层的形貌及成分变化,分析涂层的腐蚀机理.结果表明,240h盐雾腐蚀后未封孔涂层发生剥落失效,而有机硅树脂封孔涂层经1200h盐雾腐蚀表面仍保持完好.封孔涂层的耐腐蚀性明显优于未封孔涂层,有机硅树脂的封孔效果优于环氧树脂.     

Advances in room temperature curing adhesives and sealants—a review

Room temperature curing adhesives and sealants, defined here as those which cure without a mixing process under the influence of substrates or environmentally available reagents such as daylight, oxygen or moisture, include polyurethane, silicone, anaerobic adhesives, cyanoacrylate and certain acrylic types. Advances in cure chemistry, built-in adhesion promotion, and in formulating techniques have created the scope for significant new properties within all the mentioned systems. In addition, development of resins having two (or more) different functionalities, which respond to substrate and or atmospheric cure agents, has created the potential to achieve new advanced performance levels. Examples of these include compositions which give light curing through acrylic functions while having RTV (room temperature vulcanising) silicone resin chemistry polymerising under the influence of atmospheric moisture. The properties can be tailored by molecular design, formulation and choice of cure accelerators.     

High-temperature glassy-ceramic sealants SiO2—Al2O3—BaO—MgO and SiO2—Al2O3—ZrO2—CaO—Na2O for solid oxide electrochemical devices

Glasses of the SiO₂–Al₂O₃–BaO–MgO and SiO₂–Al₂O₃–ZrO₂–CaO–Na₂O systems were synthesized in the perspective to apply them as sealants in SOFC at operating temperatures of 700–900 °C. Thermal properties of the chosen glass compositions and their compatibility with the SOFC materials (YSZ-electrolyte and alloy-interconnector Crofer22APU, 15×25T) were investigated by means of synchronic thermal analysis and high-temperature dilatometry. The elemental analysis was performed by atomic emission spectroscopy. The average values of the temperature coefficients of the linear extension are 10.0×10⁻⁶ °C⁻¹ for glass 45%SiO₂– 15%Al₂O₃–25%BaO–15%MgO and 9.5×10⁻⁶ °C⁻¹ for glass 60%SiO₂–10%Al₂O₃–10%ZrO₂–5%CaO–15%Na₂O. The gluing microstructure in YSZ/glass/Crofer22APU was studied by scanning electron microscopy. The crystallization process of silicate phases was revealed to occur in the SiO₂–Al₂O₃–BaO–MgO glass. The analysis of the crystallization products was performed by Raman spectroscopy and X-ray diffraction. Glassy ceramics was proved to possess better parameters in comparison with amorphous glass to be used as a sealant in electrochemical sensors and oxygen sensors. The SiO₂–Al₂O₃–ZrO₂–CaO–Na₂O low-temperature amorphous glass can be applied in SOFC.     

Tetra‐PEG Based Hydrogel Sealants for In Vivo Visceral Hemostasis

Medical sealant devices for in vivo hemostasis are far from satisfactory in the aged society. A major challenge is effective integration of quick hemorrhage control of the increased anticoagulated patients, high safety, and facile accessibility. Here, a well‐defined ammonolysis‐based Tetra‐PEG hydrogel sealant is developed with rapid gelation speed, strong tissue adhesion, and high mechanical strength. Introduction of cyclized succinyl ester groups into a hydrogel matrix endows the sealant with fast degradable and controllably dissolvable properties. The hydrogel possesses outstanding hemostatic capabilities even under the anticoagulated conditions while displaying excellent biocompatibility and feasibility. These results reveal that the optimized hydrogel may be a facile, effective, and safe sealant for hemorrhage control in vivo.     

硅酮密封胶在铝合金隐框幕墙中的应用

铝合金隐框幕墙对硅酮密封胶的性能和质量有严格要求。文章介绍了硅酮密封胶的种类、性能及使用方法,并详细说明了采用硅酮密封胶制作结构玻璃装配组件的过程。     

单组分湿固化聚氨酯密封剂的制备、固化特性及开发应用

介绍了单组分湿固化聚氨酯密封剂的制备、固化特性及该产品的国内外发展概况，并就其开发工作提出了看法。