检索结果-南通市图书馆

Corrosion Behaviour and Chloride Attack of Reinforcing Steel in Presence of Concrete Admixtures

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1998年第4期14卷 339-343页

作者： I.Z.Selim (Physical chemistry dept., National Research Center, Dokki, Cairo, Egypt Physical chemistry dept. National Research Center Dokki Cairo Egypt

Corrosion and electrochemical behaviour of reinforcing steel embedded in cement pastes with and without concrete admixtures used in Egypt to modify concrete properties have been studied. The influence of the admixtures on the corrosion resistance of the steel against chloride attack has been studied by using impressed current and impressed voltage techniques. The results indicate that the type and concentration of the used admixture have an important effect on the extent of chloride induced corrosion of the steel. The mechanism of corrosion of steel due to chloride attack was discussed. (Edited author abstract) 16 Refs.

关键词： SCE Corrosion Behaviour and Chloride Attack of Reinforcing Steel in Presence of Concrete Admixtures Res

Infrared, Diffuse Reflectance and Dielectric Studies ofAntimony Trisulphide

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1998年第4期14卷 344-348页

作者： Hanafi, Z.M. Ismail, F.M. Khalil, M.Sh. Inorganic chemistry dept. National Research Centre Dokki Cairo Egypt

Infrared absorption spectra of orange, black and transferred Sb//2S//3 samples have been studied in the spectral range 200-4000 cm** minus **1. The pronounced difference between the different samples is the appearance of excess sulphur present in the orange and transferred samples except those of transferred at 543 K and the black Sb//2S//3. The change of sharpness of some IR peaks reveals the amorphous/crystalline change. The effect of the degree of crystallinity and stoichiometry on the energy gap values was investigated by using optical method. The obtained dielectric parameters epsilon prime and epsilon double prime of the different samples are thoroughly affected by the degree of crystallinity and smoothly affected by either the frequency or the temperature or both, except at lower frequencies. (Edited author abstract) 26 Refs.

关键词： Antimony compounds

Pitting Corrosion Behaviour of Monel-400 Alloy in Chloride Solutions

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1999年第3期15卷 208-212页

作者： V.K.Gouda I.Z.Selim A.A.Khedr and A.M.Fathi(Physical chemistry dept., National Research Centre, Dokki, Cairo, Egypt) Physical chemistry dept. National Research Centre Dokki Cairo Egypt

Pitting corrosion behaviour of Monel-400 alloy in 3.5 wt pct NaCl sodium chloride solution has been investigated using the cyclic potentiodynamic anodic polarization technique. The effect of chloride ion concentration, pH values and difFerent temperatures on the pitting parameters were determined. The morphology of the pits produced after anodic polarization treatments was inspected by scanning electron microscope (SEM). The results indicated that, the increase in chloride ion concentration shifts Epit and Eprot of the alloy toward negative values and the pitting potential is much more dependent on pH value in the basic region. The breakdown of passivity with increasing temperature may be due to kinetic changes of passivating films and dissolution rate of the alloy in its passive state

关键词： Figure Pitting Corrosion Behaviour of Monel-400 Alloy in Chloride Solutions

Binderless Carbon/Graphite Materials

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1997年第3期13卷 184-188页

作者： Zhou, SM Xia, JT Yan, LC dept. of chemistry and Chemical Engineering Hunan University Changsha 410082 China

High performance binderless carbon bodies can be manufactured from the mesophase raw material derived from petroleum pitch, which is ground into fine powders less than 10 mu m, and directly moulded, then sintered at 1000 degrees C without any kind of binder. The sintered bodies have a bulk density of 1.69 g/cm(3), bending strength of 91.2 MPa. Shore hardness of 100, porosity of only 7.2%, and electrical resistivity of 60x10(-6) Omega m. The bodies graphitized at 2800 degrees C have a bulk density of 1.88 g/cm(3), bending strength of 82 MPa. Shore hardness of 85, porosity of 5.4%, and electrical resistivity of 12x10(-6) Omega m. The scanning electron micrographs of the section show that the bodies possess an extremely dense and homogeneous structure. Infra-red spectrum analysis shows that carbonyls introduced when ground or activated are one of the key factors determining the selfbinding and selfsintering properties of the mesophase fine powders, and the structure and strength of the sintered bodies.

关键词： Carbon

Effect of inorganic additives on physical and chemical properties of PEO-LiClO_4 polymer electrolyte for lithium-ion batteries

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2009年第6期16卷 869-872页

作者：顾大明李已才杨柳王淑堂 dept. of chemistry Harbin Institute of Technology

Inorganic additives-added PEO-based solid composite polymer electrolyte (SCPE) was prepared using solution casting method. The effects of LiNi0.8Co0.2O2 on the physical and chemical properties of the electrolyte were investigated. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and differential scanning calorimetry (DSC). The electrochemical performances of SCPE were measured. Results show that properties of the SCPE are improved significantly by adding LiNi0.8Co0.2O2 into PEO polymer electrolyte. Its conductivity reaches 5×10-4 S/cm(25 ℃) while retaining good mechanical and processing properties.

关键词：聚合物电解质无机添加剂化学性质 PEO 锂离子电池物理傅立叶变换红外光谱仪氯酸锂

Effect of Sintering Temperature and Zinc Content on Some Properties of Li-Zn Ferrites

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1996年第5期12卷 329-334页

作者： A.M.El-Saird (Inorganic chemistry dept., National Research Centre, Dokki, Cairo, Egypt)S.B.Hanna(Refractories and Building Materials dept., National Research Centre, Dokki, Cairo, Egypt) Inorganic chemistry dept. National Research Centre Dokki Cairo Egypt Refractories and Building Materials dept. National Research Centre Dokki Cairo Egypt

Li-Zn mixed ferrites with composition formula ZnxLi0.5-x/2Fe2.5-x/2O4 (0.2≤x≤0.8) were prepared by the usual ceramic method in 1000~1150℃. The effects of Zn substitution and sintering temperature on the formation, densification, microstructure and a.c. electrical conductivity have been studied. Under the effect of changing the firing temperature and Zn content, high sintered Li-Zn ferrite bodies are achieved. More fine structure bodies having high electrical resistance are obtained at high Zn content

关键词： Li BDH Effect of Sintering Temperature and Zinc Content on Some Properties of Li-Zn Ferrites Zn

Assessing the impact of air pollution sources in Hong Kong, a densely populated city

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 1993年第1期5卷 1-15页

作者： Feng Yingsheng (Y. S. Fung) Department of chemistry, Hong Kong University, Hong Kong dept. of chemistry Hong Kong Univ. Hong Kong.

As the simple dispersion model tested is not sufficiently accurate to predict the SO2 concentration in complex terrain commonly encountered amongst high rise buildings in Hong Kong, and the lack of comprehensive local wind data at most sites prevents the use of more advanced dispersion model to assess the impact of major air pollutant sources, a receptor model approach is adopted for the apportionment of air pollution sources in Hong Kong. The preliminary results obtained are presented and discussed.

关键词： enviromental impact assessment dispersion model receptor model.

Statistical Characteristics of Metastable Pitting of 316 Stainless Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2000年第3期16卷 286-290页

作者： Yu ZUO, Haiou DU and Jinping XIONG (dept. of Applied chemistry, Beijing University of Chemical Technology, Beijing 100029, China) dept. of Applied chemistry Beijing University of Chemical Technology Beijing 100029 China

The statistical characteristics of the current fluctuations during metastable pitting of 316L stainless steel in NaCI solution were studied using potentiostatic method. The growth rates and peak currents of metastable pits followed log-normal distributions. As potential and chloride concentration increased, both growth rate and peak current of metastable pits increased. The lifetime of metastable pits also followed log-normal distribution, and was almost not affected by potential. Higher growth rates did not definitely result in larger metastable pits. A certain propagation rate range was found beneficial for the micropit to remain growth. At constant potential, the maximum peak currents in different time intervals during a potentiostatic test followed extreme distribution. The statistical characteristics of metastable pitting may be used to predict the tendency of pitting corrosion.

关键词： Statistical Characteristics of Metastable Pitting of 316 Stainless Steel

Diffusion of Hydrogen in Amorphous NiCrFeSiB Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1996年第1期12卷 15-18页

作者： Zuo, Y Yang, B Xu, RS dept. of Applied chemistry Beijing University of Chemical Technology Beijing 100029 China

The diffusion of hydrogen in amorphous NiCrFeSiB alloy has been studied by electrochemical method. In the temperature range of 20 similar to 50 degrees C, diffusion coefficient of hydrogen in the alloy follows the equation: D(cm(2)/s) = 9.27x10(-8) exp(-53.4 kJ/RT). At room temperature the diffusion coefficient D and the solubility C-0 are 6.125 x 10(-12) cm(2)/s and 0.007 mol/cm(3), respectively. When As2O3 is added into the cathodic solution or the charging current density is increased, the diffusion coefficient and solubility increase, and the diffusion activation energy decreases. The influence of amorphous structure on diffusion and solution of hydrogen is discussed.

关键词： Nickel alloys