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51.
The paper deals with results of thermal analysis of low-alloyed chromium-molybdenum steel. The methods of analysis were dilatometry,
differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The Ac1 and Ac3 temperatures of the steel samples measured by dilatometry and DTA during the heating period were in good agreement. Generated
by cooling a martensitic structure first became apparent at 503 K. Tempering of the as-quenched samples showed the presence
of the second tempering stage in the region between 473 and 573 K. At that stage heat capacity decreased from 0.48 to 0.32
J g-1 K-1, as a result of conversion of transition carbide due to heat consumption. After normalization of the as-quenched samples
the heat capacity values were restored to between 0.42 and 0.47 J g-1 K-1 in the temperature range from 373 to 673 K.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
52.
Yu JC Krushkova S Lai EP Dabek-Zlotorzynska E 《Analytical and bioanalytical chemistry》2005,382(7):1534-1540
A molecularly-imprinted polymer (MIP) was prepared by electropolymerization of pyrrole (Py) onto a stainless steel frit, using ochratoxin A (OTA) as the template, in order to make a micro solid phase preconcentration (SPP) device. The OTA template was removed with 1% triethylamine (TEA) in methanol. Compared to non-imprinted polypyrrole (PPy), the molecularly-imprinted polypyrrole (MIPPy) enhanced the selective binding of OTA. The percentage recovery improved from 0 to 40% when the OTA sample solution was acidified with 1 M HCl (1% by volume). At a flow rate of 0.2 mL/min, maximum OTA binding was reached in 6 min after a total loading of 3.2 ng OTA. Final elution of the OTA was analyzed by high performance liquid chromatography (HPLC) with fluorescence detection, using 20:80 v/v acetonitrile–ammonia buffer (NH4Cl/NH3, 20 mM, pH 9.2) as the mobile phase. The MIPPy-SPP-HPLC results clearly demonstrated that the MIPPy-SPP device afforded selective preconcentration of OTA from red wine samples, at OTA concentration levels as low as 0.05 ppb, prior to HPLC analysis. 相似文献
53.
Pedro de Lima Neto Mohamed Atik Luis A. Avaca Michel A. Aegerter 《Journal of Sol-Gel Science and Technology》1994,1(2):177-184
ZrO2 coatings deposited on 316 L stainless steel sheets were synthesized by sol-gel method using Zr(OC3H7)4 as precursor and isopropanol, glacial acetic acid, and water as solvents for application with ultrasounds. Different solutions for dip-coating were prepared with compositions varying between 0.025 and 0.9 mol/dm3 of ZrO2. X-ray diffraction shows that the films densified at 800°C are crystalline with a tetragonal structure. The thickness of the coatings varied from 0.35–0.75 m. The influence of the ZrO2 coatings on the corrosion behavior of stainless steel substrates in aqueous NaCl was studied through potentiodynamic polarization curves at 1 mV/s. The values of the electrochemical parameters allow for an explanation of the role of the films in the increased resistance of steel against corrosion in moderately aggressive environments. 相似文献
54.
Konrad Grob 《Journal of separation science》1992,15(3):190-194
During sample evaporation in conventional vaporizing injection, the supply of heat to the evaporating liquid is a problem, first because the amounts of heat consumed are relatively large and, secondly, because the heat must be transferred to the sample within a very short time. Times available for evaporation, required amounts of heat, possible sources of heat, and the time required to transfer the heat to the sample liquid are discussed. It is shown that mixing with carrier gas contributes little heat to the evaporation process, but also that packings with glass wool have too low a heat capacity to deliver the required amount of heat to the evaporating sample. Transfer of heat from the insert wall to the sample easily requires several seconds, even if cooling of the vaporizing zone by 20° is accepted. Thus “flash evaporation” is usually impossible and most liquids must be held in the vaporizing chamber to allow full evaporation. 相似文献
55.
In the present work, corrosion resistance of surface-coated galvanized steel was quantitatively determined by an analysis
of the alternating current (AC) impedance spectra measured on the salt-spray-tested specimen. To evaluate the corrosion resistance
of the surface-coated galvanized steel, AC impedance spectroscopy was performed on the salt-spray-tested specimen previously
exposed to salt-sprayed corrosive environment. From the analysis of the impedance spectra, the area fraction transient of
white rust θ
2(t) was theoretically derived from the equivalent circuit equation by using two fitting parameters. The values of the two fitting
parameters were determined by fitting the empirical transient equations to the area fraction of the resin coating layer and
to the total resistance obtained from the impedance spectra measured, respectively. From the analyses of θ
2(t) for four kinds of surface-coated galvanized steels with various resin coating layers, it is indicated that as the values
of the two fitting parameters decrease in the order of CP, GI, OD and OM (commercial trade names) specimens, the corrosion
resistance increases in that order as well. Furthermore, from the quantitative comparison of the two fitting parameters with
the polarization resistance of the upper resin coating layer R
p determined from the potentiodynamic polarization curve, it is suggested that the two fitting parameters decrease in value
as well with increasing R
p. 相似文献
56.
Mariusz?T.?Galkowski Pawel?J.?KuleszaEmail author Krzysztof?Miecznikowski Malgorzata?Chojak Henryk?Bala 《Journal of Solid State Electrochemistry》2004,8(6):430-434
We propose a novel composite organic-inorganic coating in the form of a redox polymer film for protection of stainless steel against general corrosion in strong acid medium (2 M H2SO4). We utilize an anion exchange polymer, protonated poly(4-vinylpyridine), into which hexacyanoferrate anions have been introduced. Owing to the presence of Fe(CN)63–/4– at the interface formed by the film and the steel, a sparingly soluble metal hexacyanoferrate (mostly Prussian blue, PB) is formed as an overcoating on the steels surface, presumably on the passive (metal oxide) layer. The redox polymer film on the steel seems to act as a composite three-dimensional bilayer-type coating in which hexacyanoferrate(III,II) anions (that are capable of effective charge storage) exist in the outer portions of the film, whereas the inner PB layer improves the systems overall adherence and stability. By analogy to a conducting polymer (e.g. polyaniline, polypyrrole), introduction of the redox polymer composite film leads to stabilization of the steel substrates potential within the passive range.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003) 相似文献
57.
Gun Wirtanen Timo Alanko Tiina Mattila-Sandholm 《Colloids and surfaces. B, Biointerfaces》1996,5(6):319-326
Biofilm growth of Bacillus subtilis, Pseudomonas fragi, Pediococcus inopinatus and Listeria monocytogenes was studied on stainless steel surfaces at room and low temperatures to evaluate the results of traditional hygiene measures. The results were compared with those of image analysis of stainless steel surfaces in an epifluorescence microscope. Statistical analyses were carried out to determine the variations between the conventional cultivation swab method, the glycocalyx amount obtained using swabbing, and the values of the areas of the biofilm, slime and cells. As a general rule, old biofilms showed total counts at approximately the same levels as the young biofilm. The results showed that temperature affected the results for all strains except B. subtilis. The strains of Pe. inopinatus and Ps. fragi showed increased attachment at 6°C and L. monocytogenes at 25°C. The biofilm slime was more easily detached than the cells. The results indicated that the traditional swab method is not reliable for the measurement of biofilm formation on surfaces. 相似文献
58.
A.?AsanEmail author M.?Kabasakaloglu M.?L.?Aksu 《Russian Journal of Electrochemistry》2005,41(2):154-158
In this study, the coverage conditions of mild steel with polypyrrole (PPy) were investigated. It was observed that the surface was passive up to 0.6 V, to the oxidation potential of pyrrole in oxalic acid solution. The PPy coverage was obtained with 0.1 M oxalic acid + 0.2 M pyrrole. A passivity mechanism supported with current potential curves was proposed. The PPy deposition was also investigated according to pyrrole and oxalic acid concentrations by successive voltammetric scans.This article was submitted by the authors in English.From Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 175–180.Original English Text Copyright © 2005 by Asan, Kabasakaloglu, Aksu.This revised version was published online in April 2005 with corrections to the article note and article title and cover date. 相似文献
59.
The inhibition performance of five azomethine derivatives such as: 1-(4-Methyloxy phenylimino)-1-(phenylhydrazono)-propan-2-one (SB1), 1-(4-Methylphenylimino)-1-(phenylhydrazono) propan-2-one (SB2), 1-(phenylimino)-1(phenylhydrazono)-propan-2-one (SB3), 1-(4-Bromo phenylimino)-1(phenylhydrazono)-propan-2-one (SB4) and 1-(4-Chlorophenylimino)-1(phenylhydrazono) -propan-2-on (SB5) as corrosion inhibitors for mild steel in sulfuric acid 0.5 ?M were investigated using different methods. All experimental results demonstrate that these compounds are eficients inhibitors. The inhibition efficiencies () increase with inhibitors concentration. At 7.5 10?5 ?M, the was 97.27%, 96.31%, 94.23%, 93.19 and 91.64% for SB1, SB2, SB3, SB4 and SB5, respectively. The potentiodynamic polarization results indicated that all the studied inhibitors act as mixed type. The adsorption process on mild steel surface obeyed Langmuir isotherm. The associated activation parameters and thermodynamic have been calculated and discussed. The adsorbed film formed on the metal surface was characterized by SEM and EDX. 相似文献
60.
表面电沉积Ni—La2O3复合镀层的Fe26Cr1Mo不锈钢的氧化行为研究 总被引:3,自引:0,他引:3
Fe26Cr1Mo不锈钢在900℃氧化时,生成的氧化层在冷却过程中大量剥落,经表面共电沉积NiLa2O3复合镀层后,抗热循环能力明显提高。 相似文献