Oscillating-cup viscometry over an extended viscosity and temperature range

The viscosity of some ZrF₄-based melts is presented and it is demonstrated that it is possible to perform reliable viscosity studies of these highly corrosive melts. Graphite crucibles have been utilized and corrections for the meniscus and the penetration into the crucible have been performed. A general discussion of oscillating-cup viscometry is given and it is shown that the present setup can be used for determination of viscosities in the range from 0.05 to above 500 mPa·s.Paper dedicated to Professor Joseph Kestin.     

多孔氧化铝陶瓷的凝胶注模成型

选用石墨粉作为造孔剂,加入已分散良好的氧化铝浆料中,球磨均匀后注模成型。成型后的坯体在1520℃保温烧结2h,获得了分布均匀,孔径为15－30μm的多孔氧化铝陶瓷。     

凝胶注模常温发泡制备氧化铝多孔陶瓷

以高纯氧化铝为原料,通过起泡结合凝胶注模成型的方法制备了孔隙率为77%～85%、孔径为40～200μm的氧化铝多孔陶瓷.多孔陶瓷组成为α-Al2O3.多孔陶瓷的微结构可通过固含量与发泡剂加入量的改变进行调控.多孔陶瓷的耐压强度为9.40～32.50MPa,且对其断裂方式进行了研究.多孔陶瓷在1000℃下的热导率为0.80 W.(m.K)-1.     

Reproduction of the volt unit over an extended range of voltages

A scale converter designed at the D. I. Mendeleev Institute of Metrology is described, which, together with the equipment of the State volt unit, makes it possible to reproduce the size of the emf unit, the volt, over an extended range of voltages (up to 10 V) with errors σ_A=7.2·10^-9 and σ_B=5.6·10^-9. Translated from Izmeritel'naya Tekhnika, No. 4, pp. 41–42, April, 1998.     

高通量氧化铝微滤膜的制备

在前有工作基础上进一步研究了氧化铝微滤膜纯水通量影响因素及其提高方法，发现制膜液粘度对纯水通量有重要影响，提高制服膜液粘度可提高膜纯水通量２￣３倍。采用有机高分子溶液预涂载体可进一步提高纯水通量３０％￣４０％。随烧结温度升高纯水通量先增后减。     

A method of calibrating voltage measuring transformers over an extended frequency range

The principle of the construction of a means for calibrating measuring voltage transformers, which enables the transformer ratios of measuring voltage transformers to be determined over a extended frequency range is considered. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 46–48, February, 2006.     

岩石渗透率节流毛细管气体流量计量测试方法研究

岩石气体渗透率是油田勘探开发最重要的基础数据之一。文章介绍了国内外岩石渗透率测试气体流量计量技术的现状，针对低渗透储层油气藏勘探开发过程中岩石渗透率测试存在的问题，开发研制了一套节流毛细管气体流量计量自动测定装置，建立了岩石渗透率节流毛细管p-g回归测试方法。该测试方法计量气体通过岩石的能力速度快，测试精度高，自动化程度高，是岩石渗透率测试技术的重大突破。     

Calibration of vacuum gauges in an expanded low pressure range

A new original method is described for calibrating vacuum gauges making it possible to cover a range of intermediate pressures from 0.01–0.1 to 1–10 MPa. Experimental data confirm the efficiency of the suggested procedure.Translated from Izmeritelnaya Tekhnika, No. 12, pp. 43–44, December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

The Effect of Thermal Decomposition on the Performance of Polymer Heat-Shielding Materials

Results are given of numerical simulation of the heating of decomposing polymer-based composite materials in a high-temperature gas flow. Numerical estimates are obtained of the effect of the thermodynamic and kinetic parameters of the process of decomposition on the calculated values of the minimal required thickness of polymer heat-shielding coatings, determined from the condition of attaining the maximum permissible temperature on the surface of the object being shielded for the preassigned period of time of thermal effect.     

The dielectric relaxation time of collagen over a wide temperature range

The dielectric properties of collagen were measured at two hydration levels over a frequency range of 10¹–10⁵ Hz and at temperatures from 298–470 K. In the low-frequency range, dielectric dispersion was observed which results from Maxwell-Wagner-Sillars polarization. The relaxation times for a collagen sample containing loosely bound water were shorter than for a collagen sample containing only structural water in the temperature range 298–390 K. Above 390 K, continuous decrease in the relaxation times was observed for both samples.     

Single-wall carbon nanotubes/epoxy elastomers exhibiting high damping capacity in an extended temperature range

In nanocomposites containing single-wall or multi-wall carbon nanotubes (SWCNT and MWCNT) high damping can be achieved by taking advantage of the weak bonding and interfacial friction between individual nanotubes and the matrix. The increase in damping capacity has already been proved for stiff epoxies and in this study it is extended to epoxy elastomers. Variable amounts (0.5–3 wt%) of oxidized SWCNT were dispersed by ultrasonication in precursors of an epoxy elastomer based on the reaction of diglycidylether of bisphenol A (DGEBA) and a polyoxypropylene with average molar mass of 2000, end-capped with primary amine groups. The quality of the initial dispersion was assessed by the constancy of the storage modulus with frequency in the low-frequency range. A rheological percolation threshold of 0.41 wt% SWCNT was found. Cured elastomers exhibited a large increase of the loss modulus with increasing amounts of SWCNT. For 3 wt% SWCNT, the increase in loss modulus was 1400% at room temperature. When temperature was increased up to 140 °C the loss modulus of the nanocomposite was practically constant while the one of the matrix dropped to a negligible value. The damping capacity at high temperatures opens important practical applications.     

不同纤维堆积状态下饱和渗透率实验研究

通过调节压力控制纤维体积分数, 用单向饱和流动法对纤维层厚度方向的饱和渗透率进行了测定。考察了纤维体积分数随压力的变化规律, 并分别研究了纤维体积分数、纤维层数、铺层方式和纤维种类对渗透率的影响。结果表明, 当纤维体积分数超过某临界值后其值随压力增大的幅度减小。单向和正交铺层时层数变化对渗透率没有影响, 而平纹布渗透率随着纤维层数的增加而减小。此外, 纤维种类的改变对渗透率有明显影响。      

Complex three‐dimensional microstructural permeability prediction of porous fibrous media with and without compaction

Much of the work in permeability prediction has so far been done with respect to the in‐plane properties. Guided by Darcy's law, the in‐plane permeabilities (i.e. Kxx and Kyy) have been well characterized by researchers both experimentally and, to some extent, analytically and numerically. Work on transverse or through thickness permeability, however, has been sparse. Owing to the fact that the limited length scale in the through thickness direction of most fibre preforms makes transverse permeability a difficult value to measure experimentally, the objective of the present development is to study the feasibility of applying the methodology proposed by the authors in a previous work for in‐plane permeability prediction to the estimation of transverse, as well as the in‐plane, permeability of a typical 3D woven fibre preform. The additional objective of this work is to present a preliminary study on the effects of fibre mat compression on the fibre preform permeability. Copyright © 2004 John Wiley & Sons, Ltd.     

我国低孔渗储层天然气资源大型化成藏特征与分布规律

低孔渗储层天然气资源是目前和未来一段时间我国天然气勘探和开发的主体,具有大型化成藏的特点。集中讨论了这类天然气资源大型化成藏的特征和分布规律,认识到成藏要素具有大型化发育与规模变化的特征,是天然气大型化成藏的基础;薄饼式、集群式成藏是天然气大型化成藏的主要样式;气源灶埋藏期规模"蓄能"和抬升期规模排气是大型化成藏重要气源输入;体积流和扩散流充注是天然气大型化成藏的主要运聚方式。低孔渗储层天然气藏的成藏分布具有近源性,成藏组合以大面积和大范围两种类型为主,成藏类型以地层—岩性圈闭为主,主要分布在海相克拉通盆地古隆起围斜区、陆内坳陷盆地广大斜坡区和向斜区以及前陆盆地缓翼斜坡等地区。低孔渗储层天然气资源大型化成藏认识的提出,提升了我国天然气资源发现潜力,扩展了勘探范围,为客观评价我国天然气主体资源总量和分布、推动有效发现大气田提供了理论基础。     

海藻酸钠离子凝胶法制备直通孔氧化铝多孔陶瓷

利用海藻酸钠的离子凝胶过程, 采用溶剂置换结合冷冻干燥的工艺, 成功制备了具有高度有序六方排列的直通孔多孔氧化铝陶瓷, 整个工艺过程及所使用的原料都是环境友好的。研究结果表明, 1500℃烧结2 h样品的孔径尺寸在200 μm左右, 且与固相含量的关系不大, 而孔壁上存在0.3 μm~0.5 μm的小孔。通过控制浆料中氧化铝的固相含量可以对材料的性能进行有效地调控, 研究表明, 随着固相含量从5wt%提高到15wt%, 材料的密度从0.87 g/cm³提高到1.16 g/cm³, 渗透率从2.57×10^-11 m²下降到2.16×10^-11 m², 而抗压强度从(18.9±3.2) MPa提高到(44.2±5.4) MPa, 平行孔道方向的热导率从2.1 W/(m·K)提高到3.1 W/(m·K), 而垂直孔道方向的热导率从1.3 W/(m•K)提高到1.7 W/(m·K), 并且平行孔道方向热导率的增加幅度要明显大于垂直孔道方向。     

无阻挡层多孔阳极氧化铝膜板的制备

提出一种在中性的KCl溶液中用多孔阳极氧化铝作阴极,通过电解在阴极产生OH-腐蚀阻挡层,制备无阻挡层氧化铝模板的新方法.用扫描电镜对模板进行了表征.结果表明,在草酸溶液中,制得的氧化铝模板孔径为70～80nm,孔间距为130nm,孔密度约8×109/cm2,这种方法去阻挡层不扩大模板孔径,不影响纳米孔的纵横比.无阻挡层的氧化铝模板适合于直流电沉积和无电沉积金属纳米材料.     

准低烧结温度条件下制备的高磁导率NiZn铁氧体

通过减小原材料粒度和在主配方中添加适量CuO,显著降低了NiZn铁氧体样品的烧结温度,在930℃低烧结温度条件下制备的NiZn铁氧体样品的晶粒更完整,组织更致密,使得材料的初始磁导率>1500。与传统工艺条件下制备的磁导率相当的NiZn铁氧体相比,本文中使用较低的NiO含量、预烧温度和烧结温度,制备的NiZn铁氧体具有更好的性能和较低的生产成本。     

Corrosion behaviour of four high temperature engineering materials exposed to landfill gas engine flue gas

Abstract

Four engineering materials commonly used in high-temperature applications were exposed to landfill gas engine flue gas for 25 days at 411°C. The flue gas was composed mostly of nitrogen and oxygen, although some carbon monoxide and hydrocarbons were detected together with low concentrations of hydrogen chloride gas and sulphur oxides. Hydrogen fluoride was not analysed, but, due to the nature of the fuel, may have been present at low levels. The materials tested were a carbon steel, a low alloy steel, a 12%Cr stainless steel and an austenitic stainless steel. Thin, protective films were formed on the 12%Cr and austenitic stainless steels, however, the corrosion products formed on carbon and low-alloy steels consisted of several layers, the outermost of which were extremely friable and non-adherent, especially on cooling from the flue gas working temperature. The maximum corrosion rate obtained was 70 μm yr^–1 for carbon steel, which may be acceptable for a number of flue gas applications. The exposed coupons were examined using conventional techniques such as X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The predominant scale formation mechanism controlling the corrosion appeared to be simple oxidation type reactions, however, the influence of HCl, as evidenced by the presence of akaganeite (β-FeO(OH)), was hypothesised. A model describing the corrosion mechanism is proposed in order to provide an improved life prediction capability for such flue gas environments.     

预烧温度对高导磁率MnZn铁氧体微结构和磁性能的影响

研究了预烧温度对高导MnZn铁氧体微结构和主要磁性能的影响,研究表明,由于预烧温度对粉体的活性产生很大影响,所以适宜的预烧温度是良好显微结构和高性能铁氧体的必要保证.适当降低预烧温度可以提高材料的磁导率,而提高预烧温度能够获得较好的频率特性.