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51.
A finite-element model has been used to study steady-state turbulent flow through bifurcated submerged-entry nozzles with oversized ports typical of those used in the continuous casting of steel. Both 2D and 3D simulations have been performed with the commercial code FIDAP, using the standard K–? turbulence model. Predicted velocities from 3D simulations compare reasonably with experimental measurements using a hot-wire anemometer conducted in a physical water model, where severe turbulent fluctuations are present. Results show that a 2D simulation can also capture the main flow characteristics of the jet existing the nozzle and requires two orders of magnitude less computer time than the 3D simulation. A model combining the nozzle and mould was set up to study the effect of the outlet boundary conditions of the nozzle on the jet characteristics. This modelling technique will assist in the design of submerged-entry nozzles, especially as applied to enhance steel quality in the continuous casting process. Further, the model will provide appropriate inlet boundary conditions for a separate numerical model of the mould. 相似文献
52.
James L. Delattre 《Applied Surface Science》2006,252(10):3912-3919
Thin films of plasma-polymerized thiophene (PPTh) were deposited on cold-rolled steel substrates to improve adhesion to rubber compounds. PPTh films were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy. The ratio of carbon-to-sulfur found in PPTh films is 4:1, suggesting the monomer structure is generally intact, which was supported by FT-IR absorptions characteristic of polymerized thiophene rings. However, some fragmentation did occur to give acetylenic and aliphatic groups. Steel-rubber adhesion measurements, performed in accordance with the ASTM 429-B peel test, strongly depended on cleaning and pretreatment methods as well as film thickness. Best results were obtained on polished steel samples that were cleaned with acid, pretreated with a hydrogen/argon plasma, then coated with 50 Å of PPTh film. These samples exhibited a peel force of 14.3 N/mm, which is comparable to that of polished brass control samples. Depth-profiling XPS analysis of the rubber-steel interface showed the existence of an iron sulfide layer which is likely responsible for the strong adhesion. 相似文献
53.
直读光谱法快速测定无锡薄钢板铬层镀铬量 总被引:2,自引:1,他引:1
本文提出了直读光谱仪测定无锡薄钢板铬层铬量的新方法。通过选用基体元素的内标元素,引入Id/I0×100%来判断原板痕量铬对实验结果的影响程度,选择合适条件,解决了薄板易击穿,确保不同铬量无锡薄板的内标元素光强直稳定性等技术关键,采用比色法制作一套不同镀铬量的标准无镀锡薄板,绘制校准曲线,方法精度RSD小于3.0%,准确度为150±5mg/m^2与经典方法比较该法操作简单,分析速度快。 相似文献
54.
Many certified reference materials are needed to calibrate and control analytical measurement processes in integrated steel
works. It is beyond the scope and capacity of most national laboratories to supply all of these needs. Yet, the demand for
these materials is steadily increasing as more steel producers update their quality systems in preparation for ISO 9000 registration
and/or ISO Guide 25 laboratory accreditation assessments. This paper describes how the Bethlehem Steel Corporation updated
its reference materials program to meet its internal needs and offers a model for use by others in improving their programs.
Received: 22 April 1998 · Accepted: 12 May 1998 相似文献
55.
赤霉素在钼蓝法测定砷,磷,硅中的应用——连续测定钢铁中的砷,磷,硅 总被引:9,自引:3,他引:9
将植物生长刺激素赤霉素引入光度分析作新显色剂,研究了赤霉素将砷、磷、硅杂多酸还原成相应杂多蓝的显色反应。在084、120、216mol/LHCl介质中,赤霉素能分别将砷、磷、硅杂多酸还原成相应的杂多蓝,其最大吸收波长分别为835、820和810nm,表观摩尔吸光系数分别为264×104、254×104和351×104L·mol-1·cm-1。线性范围分别为0~24mg/L、0~1mg/L和0~08mg/L。该法应用于钢铁中砷、磷、硅的连续测定,结果令人满意。 相似文献
56.
以热力学和动力学性质差异连续高敏测定磷和砷及其比较研究 总被引:5,自引:0,他引:5
提出以非离子表面活性剂使磷钼酸、砷钼酸-孔雀绿缔合物在水相增敏、增溶、增稳并根据磷(Ⅴ)、砷(Ⅴ)的氧化性差异及形成上述缔合物速率差异,分别建立了以热力学和动力学性质差异在水相不经分离、连续、简便、高敏测两组分的光度法,并对此两法进行了比较研究。摩尔吸光系数ε650分别为1.11×105(磷)和1.22×105(砷)L·mol-1·cm-1;服从比尔定律的浓度范围相应为0~0.24和0~0.48μg/mL。已成功地用于测定四种钢样(相对误差:热力学法皆不大于±5%,动力学法通常皆不大于±10%)和两种茶样(回收率:热力学法为98~102%,动力学法为93~111%)。 相似文献
57.
58.
Pin-ended columns having an initial imperfection in a second buckling mode and subjected to thermal loading have been studied in this paper. Based on a nonlinear relationship between strains and displacements, the buckling equilibrium equations are given with the energy method. Then the formulae for the axial compression and transversal displacement are presented. The relationship between the anti-symmetric imperfection and the axial compression has been studied along with the effect of elevated temperature on the initial imperfection. The response of the column in fire to the modified slenderness ratio is investigated. The proposed method has the potential to provide more detailed information for column designs and thus be deployed in future research to minimize the need for expensive laboratory testing. 相似文献
59.
Backing effects on the underwater acoustic absorption of a viscoelastic polymer slab embedded with locally resonant scatterers are reported. The polymer slab is embedded with two layers of locally resonant scatterers, i.e. Al spheres coated by soft silicon rubber. Theoretical absorption coefficients of the polymer slab under different backings using a layer multiple scattering method show good agreement with the experimental results, which supports unambiguously the experimental observation. Then relations between the resonance modes and the low-frequency absorption peaks of the composite slab are clarified to address the absorption mechanisms. It shows that the mass of the steel backing affects evidently the low-frequency absorption, the absorption peak shifts to lower frequency range while increasing the backing mass. 相似文献
60.
Abstract The applicability of hollow cathode and glow discharge light sources to the determination of minor constituents in steel was tested in the case of copper (0.033 ? 0.34[wt]%) and aluminium (0.015 ? 0. 16%). The linearity of the calibration graphs, reflected by the Bravais-Pearson coefficient, was found to be slightly improved in all the cases investigated when operating with hollow cathode. Furthermore, results showed that blackening values of the analytical lines can be plotted directly without resorting to reference lines. 相似文献