不等厚板过渡削薄对接焊缝的超声波探伤

不等厚板经过渡削薄处理后的对接焊缝,由于厚度的不均匀,射线穿透时的衰减不一样,对射线检测带来很大的麻烦。常用的超声波探伤方法在定位和定级方面比较困难,本文给出利用现在先进的数字式超声波探伤仪进行准确探伤的方法。     

粉煤灰填充尼龙6浇铸制品的研究

将粉煤灰用硅烷偶联剂处理后填充到尼龙6浇铸制品(MC尼龙)中,可以改善制品的吸水性、收缩率及热稳定性等,还可以降低成本。该项研究结果有很大的实用价值。     

Depolymerization of Turkish lignites. I. Effect of substituted phenols

A lignite (C, 67.4 wt%) was depolymerized with phenol, p-nitrophenol and o-chlorophenol using sulphuric acid as catalyst. The solubility of the lignite was enhanced by these treatments, with phenol being the most reactive reagent whereas p-nitrophenol was the least reactive. The distribution of nitro- and chloro-groups in the solubilized products was investigated by infrared spectrometry and it was found that these groups were redistributed among the pyridine- and methanol-soluble materials. It is suggested that benzene-soluble material is produced by self-depolymerization of coal or by degradation of pyridine- and methanol-soluble material.     

Synthesis of nano Sb-encapsulated pyrolytic polyacrylonitrile composite for anode material in lithium secondary batteries

A novel process was proposed to synthesize nano Sb-encapsulated pyrolytic polyacrylonitrile composite for anode material in lithium secondary batteries. The preparation started with the dissolution of SbCl₃ and polyacrylonitrile (PAN) in dimethylformamide (DMF) solution, followed by the addition of KBH₄ to reduce Sb³⁺ in the solution. The Sb composite was obtained by pyrolysis of the Sb/PAN mixture that precipitated out when the DMF solution was added by plentiful water. The TEM analysis showed that about 100-200 nm Sb particles were embedded by the pyrolyzed PAN, which provided a conductive matrix to relieve the morphological change of Sb during electrochemical cycling. As-prepared composite presented good cycleability for lithium storage. The proposed process paves an effective way to prepare high performance alloy based composite anode materials for high performance lithium-ion batteries.     

Simulation of the tubular positive electrode of the lead-acid battery

The discharge performance of a tubular electrode of the lead-acid battery based on a pseudo steadystate approach was simulated. It was found that the discharge reaction started from the central interior region instead of from the outer surface as in the usual plate-type electrodes. This is due to the fact that the central region has a smaller reaction surface than the outer region of the tubular electrode. This consequently causes a higher current density near the center. A comparison of the theoretical prediction and experimental result shows that the model is fairly accurate except for very high rate discharge conditions.     

Effect of Zn and Pb as alloying elements on the electrochemical behavior of brass in NaCl solutions

The electrochemical behavior of brasses with various Zn content (5.5–38 mass%) and brass (Cu–38Zn) with different Pb contents (1–3.4 mass%) in 0.6 M NaCl was investigated. The effects of temperature, immersion time, and concentration of chloride ions on the behavior of the different alloys were studied. The pitting corrosion behavior of Cu–Zn alloys and leaded–brass alloys in 0.6 M NaCl solution was also investigated. Open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS) were used. The results show that the increase in the Zn content increases the corrosion rate of the brass alloys in chloride solutions, while the increase of Pb content in Cu–38Zn–Pb decreases the corrosion rate of the alloy. Long immersion time of the alloys in the aqueous electrolyte improves their stability due to the formation of passive film on the alloy surface. The breakdown potential is shifted to more negative direction with increasing the Zn content, whereas it shifts towards positive values with increasing Pb content. Equivalent circuit model for the electrode/electrolyte interface under different conditions was proposed to illustrate the electrochemical processes taking place at the interface. The electrochemical behavior of the different alloys was discussed in view of the fitting results.     

Rapid Reactive Synthesis and Sintering of Submicron TiC/SiC Composites through Spark Plasma Sintering

Submicrometer TiC/SiC composites were fabricated by a rapid reactive sintering process through spark plasma sintering (SPS) technique using the carbon, titanium, and nanosized-SiC powders without any additive. It was found that the composite could be sintered in a relatively short time (8 min at 1480°C) to 97.9% of theoretical density. After sintering, the phase constituents and microstructures of the samples were analyzed by X-ray diffraction techniques and observed by scanning electron microscopy. The effect of nanosized and microsized SiC additives on the microstructure of TiC/SiC composites was investigated.     

在OsO_4催化作用下烯烃的立体选择性氧化反应

四氧化锇是一种贵而毒性大的试剂。本文介绍催化剂量的四氧化锇在立体选择性高的烯烃氧化反应中的应用，为四氧化锇在有机合成中的应用，开辟了新的途径。     

Alternative hydrocarbon solvents for cottonseed extraction

Hexane has been used for decades to extract edible oil from cottonseed. However, due to increased regulations affecting hexane because of the 1990 Clean Air Act and potential health risks, the oil-extraction industry urgently needs alternative hydrocarbon solvents to replace hexane. Five solvents,n-heptane, isohexane, neohexane, cyclohexane, and cylopentane, were compared with commercial hexane using a benchscale extractor. The extractions were done with a solvent to cottonseed flake ratio of 5.5 to 1 (w/w) and a miscella recycle flow rate of 36 mL/min/sq cm (9 gal/min/sq ft) at a temperature of 10 to 45°C below the boiling point of the solvent. After a 10-min single-stage extraction, commercial hexane removed 100% of the oil from the flakes at 55°C; heptane extracted 100% at 75°C and 95.9% at 55°C; isohexane extracted 93.1% at 45°C; while cyclopentane, cyclohexane, and neohexane removed 93.3, 89.4, and 89.6% at 35, 55, and 35°C, respectively. Each solvent removed gossypol from cottonseed flakes at a different rate, with cyclopentane being most and neohexane least effective. Based on the bench-scale extraction results and the availability of these candidate solvents, heptane and isohexane are the alternative hydrocarbon solvents most likely to replace hexane. Presented in part at the AOCS Annual Meeting & Expo, Atlanta, Georgia, May 1994.     

超稠油污水处理技术的研究

以河油田曙I区社84污水处理站含超稠油污水为对象，选用最新研制开发的HL－005高效除油剂，研究了药剂浓度及复合比例对污水的处理效果。结果表明，在现有工艺条件下，使用该药A与C两组分复合先对污水进行预处理,然后A与B两组分复合对预处理后的水质进行净化，在技术上是可行的，完全达到水质净化指标。