混合控制下腐蚀过程的电化学动力学参数测定

通过恒电量脉冲技术测定Q235碳钢在天然海水中腐蚀过程的电化学动力学参数. 分别利用不同极化幅度的恒电量瞬态响应分析获得极化电阻和Tafel斜率, 进而计算腐蚀电流icorr. 并对比了恒电量方法和考虑扩散影响的稳态极化曲线方法的测量结果. 结果表明, 采用恒电量强极化积分算法(CPSI)获得的Tafel斜率与极化曲线方法有很好的相关性. 同时, CPSI测定的阴极Tafel斜率符合氧还原反应的理论Tafel斜率值. 因此, 采用恒电量瞬态响应测量大大减小了浓差极化的影响, 有利于快速测定电荷传递和扩散传质混合控制下腐蚀过程的电化学动力学参数.     

Electrochemical Characterization of Stainless Steel as a New Electrode Material in a Medical Device for the Diagnosis of Sudomotor Dysfunction

An electrochemical sensor detects the risk of diabetes and prediabetes; low potentials are applied to nickel electrodes and electrical responses are measured. Although the contact of nickel with skin is short, the risk of allergical reactions cannot be discarded. SS 304L, with lower Ni content, was tested in carbonate buffer solutions containing chloride, lactate and urea to investigate its sensitivity to different parameters in sweat and compare it to nickel. The results show that SS 304L is a suitable material for the assessment of sudomotor dysfunction due to its high capacity to detect the deviation in Cl^? concentration. Sensitivity of SS 304L to Cl^? is much higher than for nickel.     

Polymer complexes. LXXVI. Synthesis,characterization, CT‐DNA binding,molecular docking and thermal studies of sulfoxine polymer complexes

Novel polymer complexes of 8‐hydroxyquinoline‐5‐sulfonic acid hydrate ( H ₂ L ) with Cu²⁺, Co²⁺ and Ni²⁺ chloride were prepared and characterized. Microanalysis, magnetic susceptibility, IR spectra, electron spin resonance, mass spectra, X‐ray, molar conductance, thermal, and UV–Vis spectra studies have been used to confirm the structure of the prepared polymer complexes. The molecular and electronic structures of the hydrogen bond conformers for ligand ( H ₂ L ) were optimized theoretically and the quantum chemical parameters were calculated. On the basis of elemental and IR data, the chemical structure of metal chelates commensurate that the tri‐dentate (H₂L) coordinate to metal chlorides through oxygen atom of phenolic OH and oxygen atom of SO₃‐H group by replacing H atoms and nitrogen of the quinoline ring. The magnetic studies suggested the octahedral geometrical structure for all produced polymer complexes with general formula {[ML (OH₂)₃] .xH₂O}_n (M = Cu²⁺, x = 1.; Co²⁺, x = 2 and Ni²⁺, x = 2) in molar ratio (1:1). Coats–Redfern and Horowitz–Metzger methods have been used for calculating the activation thermodynamic parameters of the thermal decomposition for H ₂ L and its polymer complexes. The interaction between H ₂ L and its transition metal complexes with the calf thymus DNA (CT‐DNA) was determined by UV–Vis spectra. Binding efficiency between H ₂ L with the receptors of the prostate cancer (PDB code 2Q7L Hormone) and the breast cancer (PDB code 1JNX Gene regulation) was studied by molecular docking. The inhibition behaviour of H ₂ L against the corrosion of carbon steel / HCl (2 M) solution was studied by weight loss, Tafel polarisation, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The adsorption isotherm was found to be Friendlish isotherm. The morphology of inhibited carbon steel? s surface was studied using scanning electron microscope (SEM) and energy dispersive X‐ray spectroscopy (EDS).     

Two-Step Structure Phase Transition,Dielectric Anomalies,and Thermochromic Luminescence Behavior in a Direct Band Gap 2D Corrugated Layer Lead Chloride Hybrid of [(CH3)4N]4Pb3Cl10

A direct band gap 2D corrugated layer lead chloride hybrid, [(CH₃)₄N]₄Pb₃Cl₁₀ ( 1 ), shows analogous topology to the {Mg₃F₁₀⁴⁻}_∞ layer in Cs₄Mg₃F₁₀, and with the (CH₃)₄N⁺ cations locating in the inorganic layer voids and between the interlayers. Two reversible structural phase transitions occur in 1 at 225/210 K and 328/325 K upon heating/cooling, respectively. On going from the low- to intermediate-temperature phase, the space group changes from P2₁/c to Cmca, and the crystallographic axis perpendicular to the layers is doubled with the order–disorder transformation of (CH₃)₄N ⁺ cations between the interlayers. The intermediate- and high-temperature phases are isomorphic with similar cell parameters and packing structure; their main difference concerns the disorder degree of the (CH₃)₄N ⁺ cations between the interlayers. The two-step structural phase transitions lead to dielectric anomalies around the corresponding T_c. Interestingly, 1 shows multiband emission, originating from the recombination of exciton and emission of defects. Moreover, 1 exhibits divergent thermochromic luminescent features around the T_c on the intermediate to low temperature transition.     

RAFM钢TIG焊和电子束焊疲劳性能实验和分析模拟

利用ANSYS 对低活化铁素体马氏体(RAFM)钢进行非熔化极气体保护焊(TIG 焊)与电子束焊的抗疲劳模拟分析，再利用SDS200 电液伺服疲劳试验机对TIG 焊和电子束焊的两种RAFM 钢试件进行实验。通过施加相同梯度负荷对TIG 焊和电子束焊试件进行焊缝的疲劳性能实验。与实验结果对比分析，结果显示电子束焊优于 TIG 焊，但在一定负载下可以用TIG 焊代替电子束焊。     

Dislocation-density-based constitutive modelling of tensile flow and work-hardening behaviour of P92 steel

The flow and work-hardening behaviour of tempered martensitic P92 steel have been investigated using phenomenological constitutive model in the temperature range 300–873 K for the strain rates ranging from 3.16 × 10^?5 to 1.26 × 10^?3 s^?1. The analysis indicated that the hybrid model reduced to Estrin–Mecking (E–M) one-internal-variable model at intermediate and high temperatures. Further, the analysis also indicated that dislocation dense martensite lath/cell boundaries and precipitates together act as effective barriers to dislocation glide in P92 steel. The flow behaviour of the steel was adequately described by the E–M approach for the range of temperatures and strain rates examined. Three distinct temperature regimes have been obtained for the variations in work-hardening parameters with respect to temperature and strain rate. Signatures of dynamic strain ageing in terms of the anomalous variations in work-hardening parameters at intermediate temperatures and the dominance of dynamic recovery at high temperatures have been observed. The evaluation of activation energy suggested that deformation is controlled by the dominance of cross-slip of dislocations at room and intermediate temperatures, and climb of dislocations at high temperatures.     

Modeling and numerical simulation of the resistance spot welding of zinc coated steel sheets using rounded tip electrode: Analysis of required conditions

This paper investigates the essential conditions to improve the accuracy of a resistance spot welding computational study of advanced zinc coated steel sheets using rounded tip electrode. An experimental analysis is performed to highlight the required considerations for a suitable simulation. A sequential Electrical-Thermal-Metallurgical and Mechanical (ETMM) finite element analysis with appropriate precautions of the contact conditions enables to accurately simulate the nugget development during the welding. A critical smooth evolution of the contact radius is required. A fine meshing with an interfacial mesh size of at least 0.05 × 10⁻³ m combined with a coupling time step of 0.0025 s between the electrical-thermal-metallurgical and the mechanical analysis allows a regular incrementation of the contact radius, without burdening the time computing. Accurate values of the contact resistance depending on the interfacial pressure and temperature are essential for a good simulation of the nugget size. The ETMM calculation is successfully extended to the simulation of the welding of a typical two sheets assembly.     

Microstructure change in deuterium implanted CLAM steel induced by electron irradiation

As Reduced Activation Ferritic/Martensitic (RAFM) steel is considered the primary candidate for use as a structural material in fusion power reactors,many countries are developing different kinds of RAFM.China is developing new CLAM (China Low Activation Martensitic) steel.The study investigates microstructural changes in CLAM steel implanted with deuterium ions induced by 1250 keV electron irradiation from R.T.to 873 K,and observes both the growth and shrinkage of the defect clusters produced by deuterium ...     

Application of electromagnetic processing for development of high-performance sintered powder metal parts

Electromagnetic processing was used to study the effects of electro-magneto forming on the dimensional control and thermal stability of sintered powder metal (PM) parts. The investigation was carried out on sinter-hardened, low chromium-molybdenum bainitic steel. The results show an increase in the microhardness of about 14% for the electromagnetic processed parts compared to the as-sintered parts. This was attributed to the 2% increase in the density, 17% and 29% reduction in the volume fraction of porosity and width of the bainitic lath, respectively, due to the electromagnetic processing. Dimensional characterization was carried out using a vertically aligned push-rod dilatometer. After four thermal cycles of heating and cooling, at a controlled rate of 5 °C/min to 1000 °C, the electromagnetic processed parts exhibited reduced dimensional change of about 44% lower than for the as-sintered parts. This is significantly important for applications that demand high dimensional tolerance and performance, especially at elevated temperatures.