轴承钢屑在中频炉中重熔的化学成分烧损规律

通过正交试验研究了轴承钢屑在中频感应电炉中熔炼的化学成分烧损规律,结果发现各状态下的轴承钢屑在中频感应电炉中熔炼时,其化学元素C、Cr、Mn、Si的烧损量在一定范围内波动,而有害元素P、S含量变化不大。随着钢屑熔炼前预热烘烤程度的增加,各元素的烧损也随之增加,但烘烤对钢液的精炼除气非常有利,从而为合理利用轴承钢屑提供较有益的参考数据。     

微波加热内配碳酸钙高碳铬铁粉固相脱碳

高碳铬铁无渣脱碳法可避免有毒铬渣的排放,利用微波场可快速加热粉状物料的特性,在高碳铬铁粉中配加一定比例的碳酸钙粉,可实现高碳铬铁粉快速固相脱碳.实验结果表明:配加一定比例的碳酸钙粉,不会影响内配碳酸钙高碳铬铁粉混合物料的微波加热特性;提高混合物料的脱碳摩尔比、微波加热温度和保温时间,有利于高碳铬铁粉的深度脱碳,但相应加剧脱碳铬铁粉的氧化程度.合适的固相脱碳条件为:脱碳摩尔比1∶1.0~1∶1.4,微波加热温度1100℃,保温脱碳时间60 min.在上述条件下可使碳质量分数为8.16%的高碳铬铁粉脱碳至3.91%~1.71%,脱碳率为52.08%~79.04%.     

微波加热高碳锰铁粉固相脱碳显微结构

对脱碳物料进行碳含量测定并采用电子探针及X线衍射(XRD)进行显微结构和物相分析。研究结果表明:在实验件下,高碳锰铁粉的碳含量由6.61%分别降至1.54%,1.13%,1.05%,0.94%;脱碳物料的显微结构主要为包裹与镶嵌结构、球形层状结构和实心球形结构,物相组成主要为金属锰、金属锰铁、低碳锰铁碳化物和氧化钙。脱碳温度在900℃时的综合脱碳效果最好,脱碳物料的氧化程度低且无锰酸钙等成分。     

基于废气分析的RH脱碳模型

为连续预测RH熔池内碳含量,实现对RH脱碳终点碳含量控制,以物质C平衡为基础,通过对某钢厂250 t RH废气分析系统分析的废气流量以及废气中CO、CO2含量进行连续监控,建立了基于废气分析的RH脱碳数学模型.该模型计算表明:对于冶炼成品中碳质量分数≤30×10-6的超低碳钢,模型计算RH脱碳终点碳质量分数误差都在±5×10-6之间;在RH脱碳后期,废气中CO+CO2质量分数低于5%时,熔池内脱碳速率低于10-6 min-1,此时可判定脱碳结束.同时结合现场工艺条件分析了压降平台以及吹氧操作对RH脱碳速率的影响.     

微波加热内配碳酸钙高碳锰铁粉固相脱碳试验研究

以碳酸钙为脱碳剂,采用微波加热进行高碳锰铁粉固相脱碳,可避免高温下金属锰的蒸发,实现高碳锰铁粉快速固相脱碳。试验结果表明,内配碳酸钙高碳锰铁粉在微波加热场中进行固相脱碳,脱碳物料的碳含量随脱碳温度的升高、保温时间的延长、配碳比的增加而降低。高碳锰铁粉在微波加热场中固相脱碳物料的XRD物相分析结果表明,脱碳物料的氧化程度随脱碳温度升高而加剧。综合考虑,适宜的脱碳条件为:脱碳温度1 000℃,脱碳时间为60min。内配碳酸钙高碳锰铁粉在微波加热场中和常规加热场中分别加热到900,1 000,1 100,1 200℃并保温脱碳60min,微波加热场中脱碳率分别为76.69%,82.90%,84.11%,85.75%,远高于常规加热场的脱碳率(34.14%,48.28%,49.66%,63.03%),微波加热能增强碳的扩散能力,显著提高了脱碳效率。     

钙在镁合金熔炼中的阻燃机理

熔炼了钙的质量分数为0.5%~5.0%,铝的质量分数为9.0%的10种镁合金,研究了Ca的加入对合金阻燃效果的影响.分别取定量的10种合金在700℃的高温下进行氧化增重的测量,并对合金表面的氧化形貌进行了观察.实验结果表明:镁合金加入钙后,其表面在高温下生成了CaO及少量MgO的复合致密氧化膜,这层氧化膜隔绝了空气,阻止了镁的燃烧;当钙的质量分数为3.5%时,可起到良好的阻燃效果.     

La0.8K0.2MnO3催化去除NOx和碳烟反应的研究

利用程序升温反应技术(TPR)详细考察了在La0.8K0.2MnO3催化作用下,反应气体流量、反应气中碳烟质量分数和氧体积分数变化对NOx和碳烟氧化还原反应的影响.研究结果表明,反应气体流量越低、碳烟质量分数越高,越有利于反应进行.当流量由100 mL/min减小至40 mL/min时,碳烟的起燃温度和最大燃烧温度会降低大约50℃,NOx转化为N2的最大效率则从9.7%升至19.1%;碳烟质量分数的改变对碳烟的燃烧温度基本没有影响,但NOx转化为N2的效率随着碳烟质量分数的增加而显著增加,碳烟质量分数由3%增至18%时,NOx转化为N2的最大效率从8.4%升至27.3%;氧体积分数改变对催化反应有两方面影响,氧体积分数增加能促进碳烟的燃烧,但对NOx还原有一定程度的抑制作用,当氧体积分数由2%变为5%时,碳烟的起燃温度和最大燃烧温度分别从330℃和405℃降低了30℃,NOx转化为N2的最大效率从14.5%降至11.2%.     

微波场中高碳铬铁粉固相脱碳机理研究

结合背散射电子图像、X射线衍射分析,探讨微波加热场中高碳铬铁粉的脱碳机理。分析结果表明,微波加热时,CO2首先与高碳铬铁粉中的(Cr,Fe)7C3发生反应,然后再与其他铬铁碳化物反应;保温时间一定后,提高微波加热温度,高碳铬铁粉中(Cr0.7Fe0.3)7C3的比例减小,而(Cr0.7Fe0.3)23C6和铬铁素体相(CrFe)的比例增加;由于铬易被氧化,高碳铬铁固相脱碳时,物料发生了不同程度的氧化,且温度升高,氧化程度加剧。为进一步研究微波处理冶金粉料奠定基础。     

航空轴承钢渗碳热处理组织演变行为研究

利用EPMA与XRD等实验方法对航空轴承钢在渗碳热处理过程中的微观组织演变行为进行定性及定量分析.结果表明:在渗碳淬火处理后,试样表层及次表层组织中有大量的碳化物及少量的残留奥氏体,其中碳化物为M₂₃C₆和M₆C.随着渗层深度的增加,碳化物含量减少,残留奥氏体含量增加.经过二次淬火处理后,奥氏体与马氏体中碳质量分数增加,使得淬火后残留奥氏体质量分数大幅度增加,在渗层0.1mm处达到22.7%.经过两次深冷与回火处理后,马氏体与奥氏体中碳质量分数降低,碳化物含量增加,渗层硬度提升.     

新生Fe2O3对磁铁精矿预热球团强度的影响

据磁铁精矿在空气及氮气气氛中预热的质量损失计算新生Fe2O3质量分数,研究预热温度、预热时间对新生Fe2O3质量分数的影响和新生Fe2O3质量分数对磁铁精矿预热球团抗压强度及转鼓强度的影响.研究结果表明:提高预热温度,预热球新生Fe2O3质量分数迅速增加,当Fe2O3质量分数超过50%后,其抗压强度迅速提高(大于400 N/个):同时,预热球中新生Fe2O3由邻近矿粒结晶向毗邻的氧化物体问扩散迁移并形成Fe2O3连接桥,球团强度迅速提高.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with