载气热提取法测定熔敷金属中扩散氢收集条件的探究

探究了GB/T 3965—2012《熔敷金属中扩散氢测定方法》中载气热提取法收集条件对测定扩散氢含量的影响,并与水银法进行了对比。研究结果表明,样本炉温设定为400℃,A型试块的内部温度大约在51 min时稳定在358℃左右,B型试块内部温度大约在27 min时稳定在391℃左右;载气热提取法电信号曲线收集结束点的电信号及斜率均接近0时获得的结果与水银法具有较好的一致性。     

分光光度法和光度滴定法联合测定湿法炼锌流程中钴渣浸出液中锌钴镍

湿法炼锌流程中钴渣浸出液中含有高浓度的Fe²⁺和Mn²⁺,用分光光度法测定Co²⁺和Ni²⁺时,Fe²⁺-EDTA会严重干扰Co²⁺和Ni²⁺的测定;在用光度滴定法测定Zn²⁺和Co²⁺合量时,Ni²⁺对二甲酚橙指示剂具有封闭作用,Mn²⁺亦与EDTA螯合,导致滴定结果偏高。为消除Fe²⁺和Mn²⁺对Zn²⁺、Co²⁺和Ni²⁺测定的干扰,实验进行氧化分离Fe²⁺和Mn²⁺预处理,在NaAc/Hac缓冲体系下,以EDTA作显色剂用分光光度法测定Co²⁺、Ni²⁺。在波长466nm处,Co²⁺的线性范围为50~500mg/L时与吸光度呈线性,相关系数R²为0.9992;在384nm处,Ni²⁺的线性范围为50~500mg/L时与吸光度呈线性,相关系数R²为0.9998。根据分光光度法测出Ni²⁺物质的量,加入1.1倍的丁二酮肟以除去Ni²⁺,用二甲酚橙为指示剂,EDTA鳌合-光度滴定法测定Zn²⁺、Co²⁺合量,扣减Co²⁺含量得出Zn²⁺含量。选取4个锌湿法炼锌流程中钴渣浸出液实际样品,按照实验方法中的分光光度法测定Co²⁺和Ni²⁺,光度滴定法测定Zn²⁺、Co²⁺合量,Zn²⁺、Co²⁺和Ni²⁺测定结果的相对标准偏差(RSD,n=6)均不大于0.70%,加标回收率分别为99.59%~100.41%、99.69%~100.64%、99.92%~100.08%。     

Cathode plasma electrolytic deposition of Al2O3 coatings doped with SiC particles

Semiconductor particles doped Al₂O₃ coatings were prepared by cathode plasma electrolytic deposition in Al(NO₃)₃ electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7?µm and 40?nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5?g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5?g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings.     

Beam and image experiment of beam deflection electron gun for distributed X-ray sources

Distributed X-ray sources comprise a single vacuum chamber containing multiple X-ray sources that are triggered and emit X-rays at a specific time and location. This process facilitates an application for innovative system concepts in X-ray and computer tomography. This paper proposes a novel electron beam focusing, shaping,and deflection electron gun for distributed X-ray sources.The electron gun uses a dispenser cathode as an electron emitter, a mesh grid to control emission current, and two electrostatic lenses for beam shaping, focusing, and deflection. Novel focusing and deflecting electrodes were designed to increase the number of focal spots in the distributed source. Two identical half-rectangle opening electrodes are controlled by adjusting the potential of the two electrodes to control the electron beam trajectory, and then, multifocal spots are obtained on the anode target. The electron gun can increase the spatial density of the distributed X-ray sources, thereby improving the image quality. The beam experimental results show that the focal spot sizes of the deflected(deflected amplitude 10.5 mm)and non-deflected electron beams at full width at half maximum are 0.80 mm 90.50 mm and 0.55 mm 90.40 mm, respectively(anode voltage 160 kV; beam current 30 mA). The imaging experimental results demonstrate the excellent spatial resolution and time resolution of an imaging system built with the sources, which has an excellent imaging effect on a field-programmable gate array chip and a rotating metal disk.     

Eliciting and measuring hesitance in decision-making

Hesitance is an innate human psychological phenomenon pervasive in our daily life. Although it is very complex and still not fully understood, there have been many studies related to this interesting topic. In this study, we proposed two fundamental problems about hesitance: the first is the generating problem, which is related to how to elicit hesitance information from human thinking; the second is the measuring problem, which is related to how to devise effective and reasonable methods to measure hesitance degrees from given hesitance information. With these two fundamental questions, we first discussed and analyzed several examples in real life involving hesitance, showing that it can indeed be recorded and represented. Then we roughly classified the hesitance information into two major classes: static hesitance and dynamic hesitance. Some simple and interesting methods were proposed to elicit hesitance, and more reasonable methods were proposed to measure the hesitance degree from the two classes of hesitance information. All methods that have been discussed in this study try to avoid complexity in every aspect while reserving strictness and reasonability; therefore, the present study provides suitable information for practitioners with different backgrounds.     

Controllable 1D Patterned Assembly of Colloidal Quantum Dots on PbSO4 Nanoribbons

Control of the 1D self‐assembly pattern of colloidal quantum dots (QDs) on PbSO₄ nanoribbon (NRb) templates is achieved. The internal structure of the NRbs is investigated by X‐ray diffraction, revealing the isotropic packing of the PbSO₄ nanoclusters in the NRbs. Colloidal QDs in a chloroform/hexane mixture are adsorbed onto the region close to the edges of the NRbs and form a 1D assembly of straight single line or double lines by controlling the amount of OAm. This is the first demonstration of a densely packed 1D self‐assembly of colloidal QDs with a straight line pattern without the use of any molecular bridge or adhesive. Atomic force microscopy measurements of the NRbs show depressions in the phase profile along the width of the NRbs, corresponding to the position of the 1D QD chain. The amount of adsorbed QDs on the NRbs in solution decreases as the addition of OAm increases, suggesting that additional OAm prevents interaction between the QDs and NRbs but facilitates the uniform adsorption of the 1D assembly. The low‐dimensional self‐assembly of colloidal QDs in this study opens up the possibility for the creation of anisotropically assembled QD superstructures.     

5500 m3高炉高产操作实践

分析了首钢京唐公司1#、2#两座5 500 m~3高炉开炉后快速达产、高产情况。选取连续10天以上日产量完成13 000 t的4个典型阶段,研究了高炉主要技术经济指标与操作制度的对应情况关系,总结提炼了操作经验和冶炼参数,为大型高炉高产、稳产提供了参考。     

A new cladding technology to bond aluminium on magnesium

ABSTRACT

An in situ hot press bonding technology has been developed to clad aluminium on magnesium. Followed by regular hot rolling, magnesium sheets, covered by ductile and corrosion-resistant aluminium without detectable oxides in the interface, are produced. The new technology requires no welding, vacuum, protective atmosphere or barrier layer, and it makes good interfacial strength and rollability. Aluminium–magnesium intermetallic phases are formed along the clad–core interface at elevated temperatures. They are not detrimental under compression but may cause clad-core delamination in tensile strain. However, the tensile failure is more dependent on the formability of magnesium core than on the strength of interface.     

High‐Purity Tocored Improves the Stability of Stripped Corn Oil Under Accelerated Conditions

γ‐Tocopherol‐5,6‐quinone (tocored) is of importance among the γ‐tocopherol (γ‐T) oxidant products and found in corn germ oil. Investigation on tocored is impeded in part by the difficulty to access high purity tocored. In this present study, high‐purity tocored is successfully prepared, and its antioxidant activity, together with γ‐T and TBHQ (positive control) in increasing concentrations in stripped corn germ oil is evaluated by Rancimat and Schaal oven tests. The stabilization factor in the Rancimat tests increases significantly (p < 0.05) along with an increase in the levels of antioxidants. Furthermore, tocored exhibits higher stabilization than γ‐T in the Schaal oven tests, although its efficacy gradually increases up to 100 mg kg^–1 and decreases significantly at higher levels (from 100 to 500 mg kg^–1), drawn from the comprehensive parameter A (considering both efficiency and strength) changes (5.06–11.21). In addition, the curves illustrating the residual contents of tocored and γ‐T run in different ways when the four levels are taken into consideration, further bearing the above results. Tocored tends to be a potent natural antioxidant for edible corn germ oil preservation. Practical Application: The present work provides more clear procedures for high‐purity tocored synthesis. Furthermore, tocored may be a potential natural antioxidant that is especially suitable for lipid base food substrates. The results of the present work contribute to the deeper understanding of the antioxidant activity of γ‐tocopherol. The antioxidant activity of tocored is higher than γ‐tocopherol in Schaal oven test. Tocored is a bright orange‐red substance that affects the appearance of the edible oil. Meanwhile, γ‐tocopherol is well known for its valuable health benefits, and appropriate measures should be adopted to store oils (corn oil, soybean oil, and so on) rich in γ‐tocopherol to control transformation in order to keep stability optimal. To some degree, the practical applications of the present results are also related to the processing and storage of edible oils.