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inhibitive Effect of Some Aldehydes on Corrosion ofAl-3Mg Alloy in Acid Solutions

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Journal of Materials Science & Technology 1998年第4期14卷 313-319页

作者： i.z.selim (Physical Chemistry Dept., National Research Center, Dokki, Cairo, Egypt) Physical Chemistry Dept. National Research Center Dokki Cairo Egypt

2M hydrochloric acid solution was used and the methods of polarization and weight loss measurements were adopted. The two methods give the same order of inhibition efficiency. Polarization studies reveal that catholic polarization is more pronounced than the anodic one. The results indicate that all the studied compounds excellent corrosion inhibitors and the percentage efficiency varying with both the type and concentration of the inhibitor and being in the following order: p-methoxy-benzaldehyde (1)benzaldehyde (2)p-chlorobenzaldehyde (3)p-nitrobenzaldehyde (4). The degree of surface coverage of the adsorbed additives was determined and the results obey the Langmuir isotherm. Effect of temperature on the corrosion rate in absence and presence of different concentrations of the used inhibitors was investigated by using weight loss measurements. The results indicate that the corrosion rate rapidly increases with increasing temperature. (Edited author abstract) 19 Refs.

关键词： Champion benzaldehyde blank Adsorption Singh Pearson Chapman Egypt London

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

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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

Pitting Corrosion Behaviour of Monel-400 Alloy in Chloride Solutions

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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

Dielectric Properties of Some Aldehydes

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Journal of Materials Science & Technology 1995年第3期11卷 222-228页

作者： i.M.El-Anwnr and i.z.selim (Physical Chemistry Dept., National Research Centre, Dokki, Cairo, Egypt)A.A.Foad(Faculty of Science, Helwan University, Helwan, Cairo, Egypt) Physical Chemistry Dep National Research Centre Dokki Cairo Egypt

The apparent solution dipole moment, μ, the association factor S, and the correlation parameter g for some aldehydes are calculated at different temperatures. The results are discussed and compared with previous results. The dielectric constant ε' and loss ε' for the investigated aldehydes were measured with different frequencies at 10-50℃. The variation of permittivities with both temperature and frequency is discussed. The relaxation times τ, for some aldehydes were calculated at different temperatures and its values were used in the calculation of the thermodynamic parameters △H and △S

关键词： Am Dielectric Properties of Some Aldehydes

Corrosion Behaviour of Stainless Steel in Acidic Water-Organic Solvent Mixtures

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Journal of Materials Science & Technology 1994年第6期10卷 411-417页

作者： A .A.Khedr i.z.selim K.M.El-Sobki and O.S.Shehata(Physical Chemistry Dept., National Research Centre, Dokki, Cairo, Egypt) Natl Research Cent Cairo Egypt

Electrochemical behaviour of stainless steel type 430 in acidic solutions of methanol, ethanol and in their binary mixtures with water (from 0 to 100% alcohol) at 25℃ has been studied. using potentiostatic poiarization technique and weight loss method. it was found that the corrosion rate of the metal was affected by the physico-chemical properties of the media such as, viscosity, state of solvation, molar volume contraction, proton availability and dielectric constant, it was demonstrated from the potentiostatic study that the active passive transition strongly depended on the concentration of the acid, and on the water content of the media.

关键词： Stainless steel

improvement of Concrete Properties and Reinforcing Steel inhibition Using a Natural Product Admixture

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Journal of Materials Science & Technology 1996年第2期12卷 95-99页

作者： S.H. Tantawi (Building Research institute, Dokki, Cairo, Egypt)i.z.selim (Physical Chemistry Dept., National Research Center, Dokki, Cairo, Egypt (To whom correspondence should be addressed) Building Research institute Dokki Cairo Egypt Physical Chemistry Dept. National Research Center Dokki Cairo Egypt

The use of a natural white juice, taken from magrabe banana stem, as concrete admixture to improve mechanical and physicrvchemical properties of concrete has been studied. The compressive strength, bulk density the free lime liberated during hydration and the combined water content were determined. The results indicate that the admixture acts as a retarder in most cases and as accelerator in some ones. Also, the admixture effect on the corrosion resistance of the reinforcing steel against surrounding aggressive media has been investigated using galvanostatic polarization technique. The addition of 0.2% admixture leads to the more inhibition of the steel

关键词： pH Figure improvement of Concrete Properties and Reinforcing Steel inhibition Using a Natural Product Admixture OH

Corrosion Measurements of Reinforcing Steel by Different Electrochemical Techniques

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Journal of Materials Science & Technology 1995年第6期11卷 447-451页

作者： S.M.Morsy (Metallurgy Dept. Nuclear Research Center, Atomic Energy Authority, Cairo, Egypt) i.z.selim (Physical Chemistry Dept., National Research Center, Dokki, Cairo, Egypt)S. H. Tantawi (Building Research institute, Dokki, Cairo, Egypt) Atomic Energy Authority Cairo Egypt

Electrochemical techniques of the corrosion measurements of reinforcing steei in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current method and potentiostatic polarization technique. The results of corrosion behaviour of the steel in both 5%NaCl and 5%MgSO4 show that each electrochemical technique provides some information about the condition of the steel bar or the corrosivity of the environment being evaluated, yet none provides a complete data regarding the corrosion resistance of reinforcing steel in aggressive media

关键词： Corrosion Measurements of Reinforcing Steel by Different Electrochemical Techniques

Dielectric Behaviour of Mixtures of Polyethylene Glycol with Propionaldehyde and Benzaldehyde

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Journal of Materials Science & Technology 1995年第5期11卷 373-379页

作者： i.M.El-Anwar and i.z.selim(Physical Chemistry Dept., National Research Center, Dokki, Cairo, Egypt)( To whom correspondence should be addressed)(To whom correspondence should be addressed)A.A.Foad(Faculty of Science, Helwan University, Helwan, Cairo, Egyp

The dielectric constant e' and dielectric loss e' of several mixtures of propionaldehyde-polyethylene glycol (system 1) and benzaldehyde-polyethylene glycol (system ii) have been measured within the frequency band 105-107 Hz and the temperature range 20-50℃. The dielectric behaviour is discussed. on the other hand, the dielectric relaxation time T. activation energy △He, and entorpy change △Se for the dielectric relaxation as well as activation energy of viscous flow △Hv are calculated for the same temperature range. it is suggested that the observed increase in T values with *** glycol content is due to an increase in the hydrogen bonding in the aggregates or clusters which would be formed between the carbonyl group of the aldehyde and the hydrogen atoms from the glycot molecules. in addition， the higher values of T, △He, and △Se in case of system (ii) than that in case of system (i) may be due to the greater volume of the aggregates and the stronger dipole-dipole forces in system (ii) compared with those in system (i).

关键词： ii Figure Dielectric Behaviour of Mixtures of Polyethylene Glycol with Propionaldehyde and Benzaldehyde

Precipitation of multi-type nano-quasicrystals in a Mg-zn-Y alloy

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Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： W.z.Wang X.z.zhou L.F.zhang H.Q.Ye z.Q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.