暗渠联结井闸碳化治理

指出碳化对水工钢筋混凝土结构耐久性有重要的影响,结合工程实例,对混凝土碳化破坏原因进行了分析,并提出了详细的治理方法和工艺,通过补强加固提高了钢筋混凝土结构的耐久性。     

混凝土结构损坏机理的主要因素

从钢筋的锈蚀、混凝土的碳化、氯化物侵蚀、混凝土的冻融破坏、混凝土的碱—骨料反应五个主要因素入手,对混凝土结构损坏机理进行了分析,以期指导实践,提高混凝土结构耐久性,延长其使用寿命。     

Physicochemical properties and structural evolutions of gas-phase carbonization chars at high temperatures

The gas-phase carbonization chars from hydrocarbons with low molecular weight (anthracene oil and petroleum ether) were prepared using a drop tube reactor at 1000-1200 °C, and their physicochemical properties and structural evolutions (elemental composition, carbon crystallite structure, surface morphology, pore structure and chemical composition of volatile matters) were mainly investigated. The chars obtained in the high temperature region, which appeared with high C/H atomic ratio and poor carbon crystallite structure far from natural graphite, could be used as high carbonaceous materials. The chars were composed of uniform spherical particles with a continuous pore size distribution. The average pore diameters of the chars were much smaller and in the rage of 5.0-8.7 nm. The increasing carbonization temperature led to an initial increasing and a sequent decreasing of specific surface areas from mico-meso-pores and an increasing of those from meso-macro-pores in the chars. The volatile matters in the chars were composed of an easily-extracted fraction (CS₂-soluble compounds with three to six aromatic rings) and a hard-extracted fraction (CS₂-insoluble compounds with higher aromaticity). The elevated carbonization temperature led to diminish the two volatile fractions. A liquid core formation mechanism was proposed to explain the gas-phase carbonization process of hydrocarbons.     

金安桥水电厂500kV变压器故障分析

通过对一起变压器油色谱气体成分超标分析及故障排除检查,并结合计算数据,印证了分析的准确性,充分说明了对初投运变压器加强油色谱分析的重要性。     

三渣基层裂缝成因初探

对三渣基层裂缝的成因机理及外部因素影响进行了初步研究。阐明要减少或消除三渣基层裂缝的发生 ,应从修正混合料配合比、改善骨灰比、调整内部结构减低二灰含水量等因素入手 ,同时对三渣基层下土路基填挖、河浜、鱼塘、圆涵及过路管线等回填土质量亦不可忽视     

水工碳化混凝土微观试验研究

采用压汞法研究近50年龄期的水工混凝土的微观结构。试验表明,混凝土碳化层较未碳化层孔径增大,总孔隙率变大,最可几孔径变大,使得混凝土碳化层强度低于未碳化层强度。     

对现行回弹法规范测定矿物掺合料混凝土碳化深度方法的质疑

通过工程实例,论述了采用现行规范《回弹法检测混凝土抗压强度技术规程》来测碳化深度,并且使用附录A(测区混凝土强度换算表)来推定混凝土强度。测定碳化深度时会出现严重偏差和失真,最终导致回弹法测得的混凝土强度出现严重偏差和失真。并提出了解决方案。     

无熟料矿渣水泥混凝土碳化特性研究

无熟料矿渣水泥混凝土(NSC)是一种新型水泥混凝土,其碳化性能取决于水淬高炉矿渣的碱度、化学成分、玻璃化率以及激发剂的种类和数量.以石膏和石灰作为激发剂配制NSC后进行快速碳化试验.结果表明,NSC的碳化程度普遍大于普通混凝土,主要原因在于NSC在水化过程中几乎不生成Ca(OH)2.但添加少量的防碳化剂后,其碳化程度与普通混凝土基本相同.     

Preparation and characterization of carbon fibers from polyacrylonitrile precursors

The present work deals with the preparation of carbon fibers from polyacrylonitrile (PAN) fibers. The chemical composition and physical properties of the starting fibers were determined. The PAN fibers were stabilized in air at the temperatures (230, 270, and 300°C) with the heating time from 40 to 420 min. The effects of both final stabilization temperature and heating rate on the chemical and physical properties of the prepared stabilized fibers were studied. The chosen stabilized fibers samples were carbonized in argon atmosphere at the temperatures (1000, 1200, and 1400°C) with different heating rates 5, 10, 15, and 20°C min^?1. The effects of both carbonizing temperature and heating rate on the weight loss, density, elemental composition, and IR absorption spectra of carbonized fibers were also studied. The fiber sample, which was carbonized at 1400°C, contains 97.55% carbon, 1.75% nitrogen, and 1.4% hydrogen. This means that carbonizing the stabilized fibers at 1400°C in argon atmosphere is suitable to get oxygen‐free carbon fibers. Therefore, the used carbonizing temperature in the present work (1400°C) is suitable to produce moderate heat‐treated carbon fibers with the heating rate of 15°C min^?1. The modulus of the prepared carbon fibers was compared to that of industrially produced fibers using the results of X‐ray analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

预处理条件对Fe-Mn催化剂催化CO加氢合成低碳烯烃性能的影响

制备了一系列Fe-Mn催化剂,考察了预处理条件对其催化CO加氢合成低碳烯烃性能的影响。实验结果表明,用CO处理的催化剂较用H_2处理的催化剂具有较高的烯烃选择性;在CO气氛、300℃下还原4h的催化剂上,产物C_(2～4)烃中烯烃与烷烃的质量比可达5.88;碳化温度升高,重质烃含量增加;但在CO气氛、400℃下还原4h的催化剂上,产物中重质烃含量有所下降。XRD和XPS表征结果显示,用CO处理的催化剂中有碳化物生成,且高温、CO处理的催化剂表面有大量的碳化物生成;CO_2(CO)-TPD表征结果显示,碳化过程增强了催化剂的表面碱性,增强了CO的吸附能力,相对加氧能力减弱,烯烃选择性提高,促进了链增长。但同时CO吸附能力的增强,促进了CO高温预处理下的碳沉积,进而抑制了重质烃的生成。