新型催化材料Sr2FeMoO6的葡萄糖溶胶-凝胶法合成及甲烷催化燃烧性能

采用葡萄糖溶胶-凝胶法合成了Sr₂FeMoO₆催化剂,研究了空气、氩气和H₂/N₂ 3种焙烧气氛对产物的结构和性能的影响。运用X射线衍射（XRD）、程序升温还原（TPR）、傅里叶变换红外光谱（FT-IR）、比表面（BET）及磁性测量与甲烷催化燃烧活性评价等技术对所制备的样品进行了表征。XRD实验结果表明,H2/N2气氛下焙烧得到的样品是单相的双层钙钛矿结构氧化物Sr₂FeMoO₆,在氩气下焙烧的样品形成了主相为双层钙钛矿结构氧化物Sr₂FeMoO₆,同时伴有少量的SrMoO₄相,但在空气下焙烧的样品中除了Sr₂FeMoO₆的衍射峰,还出现了强度很高的SrMoO₄相的衍射峰。从TPR、FT-IR和磁性表征结果发现,不同的焙烧气氛所形成的样品程序升温还原图谱和红外光谱均有所差别,H₂/N₂气氛下合成的样品有较好的磁性,而氩气和空气下合成的样品的磁性几乎为零。对于H₂/N₂气氛下合成的单相Sr₂FeMoO₆样品的甲烷催化燃烧活性测试表明,甲烷燃烧起燃温度T₁₀为475℃,完全转换温度T₁₀₀为744℃,可见单相双层钙钛矿型结构化合物Sr₂FeMoO₆对甲烷催化燃烧也有很好的活性。     

玻璃纤维增强聚丙烯管材热熔焊焊接工艺研究

为了解决玻璃纤维增强聚丙烯管材在焊接过程中出现的气孔、错边和未熔合等缺陷,对玻璃纤维增强聚丙烯管材热熔焊焊接工艺进行了研究,为相关管道施工提供工程依据。     

节镍不锈钢的开发与展望

近年全球镍金属价格上涨,不锈钢节镍非常必要.节镍不锈钢主要有铁素体不锈钢,Cr-Mn-Ni-N奥氏体不锈钢与含N的双相不锈钢.重点对超铁素体不锈钢与新型Cr-Mn-Ni-N奥氏体不锈钢与节镍双相不锈钢作了介绍.     

Ionic double layer of atomically flat gold formed on mica templates

Electrical impedance spectroscopy characterisations of gold surfaces formed on mica templates in contact with potassium chloride electrolytes were performed at the electric potential of zero charge over a frequency range of 6 × 10⁻³ to 100 × 10³ Hz. They revealed constant-phase-angle (CPA) behaviour with a frequency exponent value of 0.96 for surfaces that were also characterised as atomically flat using atomic force microscopy (AFM). As the frequency exponent value was only marginally less than unity, the CPA behaviour yielded a realistic estimate for the capacitance of the ionic double layer. The retention of the CPA behaviour was attributed to specific adsorption of chloride ions which was detected as an adsorption conductance element in parallel with the CPA impedance element. Significant variations in the ionic double layer capacitance as well as the adsorption conductance were observed for electrolyte concentrations ranging from 33 μM to 100 mM, but neither of these variations correlated with concentration. This is consistent with the electrical properties of the interface deriving principally from the inner or Stern region of the double layer.     

Investigation of the stress and strain state of clay pipes under fire condition

The focus of this paper is given to investigating the testing and evaluation method of stress and deformation behaviour of clay pipe elements like chimneys under cyclic high temperature. The experimental study on the temperature–time curves and on the radial deformation–temperature curves of a series of fire-resistant clay pipes was carried out. The tensile strength and the compressive strength, the elastic modulus before and after fire, the stress and deformation properties and the cracking behaviour of the clay pipes under fire conditions have been analyzed. The theoretical analysis corresponds well with the experimental results and tends to prove that the elastic deformation can be the most significant component in fixed-end clay pipes. This study is useful for evaluation of the stress–strain properties of ceramic pipes and provides a beneficial test method for the pipe member in small-scale or in full-scale tests under fire temperatures.     

Activation of ultra‐thin activated carbon fibers as electrodes for high performance electrochemical double layer capacitors

Activated carbon fibers (ACFs) contain pores with a weak resistance to electrolyte migration but with high electrical resistance between the fibers. The ACFs used herein were prepared from ultra‐thin polyacrylonitrile (PAN) fibers, to be used as electrodes in electrochemical double layer capacitors (EDLCs), by varying the activation temperatures and the holding times during steam activation. As the activation temperature and holding time were increased, the specific surface area increased along with the specific capacitance (F g^?1). A maximum specific capacitance as high as 283 F g^?1 can be obtained using the ultra‐thin ACFs fabricated at 1000°C for 10 min with a specific surface area of 1408 m² g^?1. This investigation demonstrates that the surface area, pore structure, and surface functional groups of ACFs were all significant factors in determining the capacitive characteristics of ACFs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rubber/LDH nanocomposites by solution blending

The rubber nanocomposites containing ethylene vinyl acetate (EVA) having 60 wt % of vinyl acetate content and organomodified layered double hydroxide (DS‐LDH) as nanofiller have been prepared by solution intercalation method and characterized. The XRD and TEM analysis demonstrate the formation of completely exfoliated EVA/DS‐LDH nanocomposites for 1 wt % filler loading followed by partially exfoliated structure for 5–8 wt % of DS‐LDH content. EVA/DS‐LDH nanocomposites show improved mechanical properties such as tensile strength (TS) and elongation at break (EB) in comparison with neat EVA. The maximum value of TS (5.1 MPa) is noted for 3 wt % of DS‐LDH content with respect to TS value of pure EVA (2.6 MPa). The data from thermogravimetric analysis show the improvement in thermal stability of the nanocomposites by ≈15°C with respect to neat EVA. Limiting oxygen index measurements show that the nanocomposites act as good flame retardant materials. Swelling property analysis shows improved solvent resistance behavior of the nanocomposites (1, 3, and 5 wt % DS‐LDH content) compared with neat EVA‐60. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

套管式高压氨加热器内管泄漏原因分析及技术改进

分析高压氨加热器内管泄漏的原因,采用将氨加热器更换为TPC型电加热器的技术改造措施,彻底解决了内管泄漏问题,保证了三聚氰胺装置稳定运行。     

在用工业压力管道穿孔泄露原因的分析

在对在用压力管道定期检验中,发现管道穿透性泄露,根据不同检测方法进行检测,结合现场情况和运行参数,对缺陷产生进行分析,消除缺陷,并优化管道线路。压力管道的安装质量已经有了较完善的监督管理,监督部门能够通过安装的重要环节进行监督和控制。在相关检规出台后,引起各有关部门的重视,逐步实现征力管道定期检验,消除潜在或再生的安全隐患,确保人民的生命和财产的安全。     

聚乙烯管材发生慢速裂纹增长的影响因素及对策

耐慢速裂纹增长性能是提高聚乙烯（PE）管材耐用性的关键因素。文章综述了PE管材发生慢速裂纹增长的机理和影墒因素,最后给出了提高PE管材耐慢速裂纹增长性能的改进措施。