Synergistic effect of iodide ions on the corrosion inhibition of steel in 0.5 M H2SO4 by new chalcone derivatives

The effect of addition of 4′,4-dihydroxychalcone (P₁), 4-aminochalcone (P₂) and 4-bromo, 4′-methoxychalcone (P₃) on the corrosion of steel in 0.5 M sulphuric acid has been studied by weight loss measurements, potentiodynamic and EIS measurements. We investigate the synergistic effect of iodide ions on the corrosion inhibition of steel in the presence of chalcone derivatives. The corrosion rates of the steel decrease with the increase of the chalcones concentration, while the inhibition efficiencies increase. The addition of iodide ions enhances the inhibition efficiency considerably. The presence of iodide ions increases the degree of surface coverage. The synergism parameters S_Θ and S_I, calculated from surface coverage and the values of inhibition efficiency, in the case of chalcone derivatives are found to be larger than unity. The enhanced inhibition efficiency in the presence of iodide ions is only due to synergism and there is a definite contribution from the inhibitors molecules. E (%) obtained from the various methods is in good agreement. Polarisation measurements show also that the compounds act as cathodic inhibitors.     

The inhibitive effect of bipyrazolic derivatives on the corrosion of steel in hydrochloric acid solution

The effect of two pyrazole-type organic compounds, namely ethyl 5,5′-dimethyl-1′H-1,3′-bipyrazole-3 carboxylate (P1) and 3,5,5′-trimethyl-1′H-1,3′-bipyrazole (P2) on the corrosion behaviour of steel in 1 M hydrochloric acid (HCl) solution is investigated at 308 K by weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods. The inhibition efficiencies obtained from cathodic Tafel plots, gravimetric and EIS methods are in good agreement. Results obtained show that the compound P2 is the best inhibitor and its efficiency reaches 84% at 10⁻³ M. Potentiodynamic polarisation studies show that pyrazolic derivatives are cathodic-type inhibitors and these compounds act on the cathodic reaction without changing the mechanism of the hydrogen evolution reaction. The inhibition efficiency of P2 is temperature-dependent in the range from 308 to 353 K and the associated activation energy has been determined. P2 adsorbs on the steel surface according to Langmuir adsorption model. The calculation of the total partial charge of inhibitor atoms is computed.     

电感耦合等离子体-原子发射光谱法测定不锈钢材料中钴、铜、钒

应用电感耦合等离子体-原子发射光谱法(ICP-AES)对测定不锈钢材料中钴、铜、钒三种元素进行了试验研究.取样量为2.0 mg/mL时,测定范围在125-2000 μg/g之间,相对标准偏差(RSD,n=6)在1.8%-6.7%之间.     

Evolution of ZnO nanostructures by non-catalytic growth process on steel alloy substrate: Structural and optical properties

Various kind of ZnO nanostructures such as nanowires, nanonails and nanocombs were synthesized by the thermal evaporation process onto the steel alloy substrate without the use of metal catalyst or any additives. Detailed structural characterizations indicated that the grown products possess a single crystallinity with the wurtzite hexagonal crystal structure. Presence of strong optical-phonon E₂ mode, in all the cases, presents the good crystallinity with the wurtzite hexagonal phase for the deposited products. Additionally, appearance of dominated, strong and sharp UV emission in the room-temperature photoluminescence spectra confirmed the good optical properties for the grown nanostructures. A vapor–solid growth mechanism has been proposed for the growth of the nanostructures.     

固体薄层纵深分析研究——Ⅱ.钢、铝合金和钛合金溅射速率的测定

用PHI 600型扫描俄歇探针、200型台阶仪和Q-920型图象分析仪,测定了35Cr Ni3MoV钢、Al-5.5 Zn-1.4Mg合金和Ti-5Al-2.5Sn合金的溅射速率,提出了对蚀坑分部位确定溅射速率的方法。文中给出了详细的测定结果。     

Infrared Image Processing for the Calorimetric Analysis of Fatigue Phenomena

This paper presents an infrared image processing procedure that was developed to study calorific effects accompanying material fatigue. This method enables us to separately estimate patterns of thermoelastic and dissipative sources. Heat sources were estimated on the basis of partial derivative operators present in a local form of the heat equation by using a set of approximation functions that locally fits the temperature field and takes the spectral properties of the sought sources into account. Numerical examples were used to check the validity of the method and to highlight its capabilities along with its limits. The paper concludes with examples of thermal image processing extracted from fatigue tests performed on a dual-phase steel. The coupling sources were compared to the theoretical predictions induced by a basic thermoelastic model, while the heterogeneous character of the fatigue development was highlighted in terms of dissipation sources.     

氯离子侵蚀下钢筋在混凝土中腐蚀行为的EIS研究

应用电化学阻抗谱(EIS)研究环境介质中氯离子对混凝土中钢筋腐蚀行为的影响.结果表明,在测量的频率范围内,钢筋混凝土体系的阻抗谱图包含两个时间常数,分别对应于界面的双电层和钢筋表面的混凝土保护层.其低频段的半圆有些压扁,表明界面双电层的充放电行为偏离理想电容器,可归因于钢筋表面的不均一性.在浸泡后期,低频段出现拖尾,同时电荷转移电阻Rct减小了近两个数量级,这是由于钢筋表面的钝化膜已经破裂,发生活性腐蚀,况且氯离子浓度的增大加速了腐蚀发展过程.讨论了混凝土中在钢筋腐蚀发生,发展的过程中,其腐蚀电位Ecorr以及等效电路中的Rct和Warburg阻抗等元件的变化特征.     

Innovative reconsolidation of carbon steel machining swarf by laser metal deposition

The concept of widespread recycling of metals in order to save cost, energy and ecological damage is gaining importance and this necessitates not simply disposing of machining waste. In this work a new way of reconstituting chips/swarf into a usable solid structure is explored by using them in place of metal powder in laser direct metal deposition. Samples of carbon steel machining swarf in three size ranges are reconstituted and the final structural characteristics like clad dimension, microstructure and physical properties are analysed. The results show that it is possible to reproduce a material that has full density, fine microstructure and no significant contamination from an unprecedented size and shape of particles. As general trends, individual deposition tracks become lower, wider and less hard as particle size increases. This work shows that the laser deposition process can be used with a larger range of particle geometries than previously considered and this could be the point leading to a new ‘local’ recycling method.     

Miniaturized Compression Test at Very High Strain Rates by Direct Impact

A modified miniaturized version of the Direct Impact Compression Test (DICT) technique is described in this paper. The method permits determination of the rate-sensitive plastic properties of materials up to strain rate ∼10⁵ s⁻¹. Miniaturization of the experimental setup with specimen dimensions: diameter d _S = 2.0 mm and thickness l _S = 1.0 mm, Hopkinson bar diameter 5.2 mm, with application of a novel optical arrangement in measurement of specimen strain, makes possible compression tests at strain rates from ∼10³ s⁻¹ to ∼10⁵ s⁻¹. In order to estimate the rate sensitivity of a low-alloy construction steel, quasi-static, Split Hopkinson Pressure Bar (SHPB) and DICT tests have been performed at room temperature within the rate spectrum ranging from 5*10⁻⁴ s⁻¹ to 5*10⁴ s⁻¹. Adiabatic heating and friction effects are analyzed and the final true stress versus true strain curves at different strain rates are corrected to a constant temperature and zero friction. The results have been analyzed in the form of true stress versus the logarithm of strain rate and they show two regions of a constant rate sensitivity : relatively low up to the strain rate threshold ∼50 s⁻¹, and relatively high above the threshold, up to strain rate ∼4.5*10⁴ s⁻¹.     

A study on an axial crush configuration response of thin-wall, steel box components: The quasi-static experiments

An experimental investigation was performed to study a specific axial crush configuration response of steel, square box components under quasi-static testing conditions. For a specific cross-sectional geometry/fabrication process, test specimens were obtained from commercially produced, welded tube lengths of ASTM A36 and ASTM A513 Type 1 plain low-carbon steels and AISI 316 and AISI 304 austenitic stainless steels. Removable grooved caps were used to constrain tube test specimen ends, and collapse initiators in the form of shallow machined grooves were used to control the initial transverse deformations of the test specimen sidewalls. The progressive plastic deformation for all of the test specimens was restricted to the prototype configuration response (fold formation process and the corresponding axial load-axial displacement curve shape) of the symmetric axial crush mode. Crush characteristics were evaluated and, for each material type, observed differences were less than 7% for maximum and minimum load magnitudes and less than 2% for energy absorption, displacement, and mean load quantities in both the initial phase and the secondary folding phase cycles. Overall, results of the study indicate that for a significant range of material strengths, a controlled and repeatable energy absorption process can be obtained for commercially produced steel box components undergoing symmetric axial crush response.