Computer Simulation of Internal Thermal Field Change in Titanium Sponge Reactor

采用Fluent商用软件,对海绵钛生产环节中处于还原阶段的反应釜内部热场变化进行了计算机模拟,揭示了还原过程中反应釜内部热场变化的分布;结合反应釜内部热场变化分布的特点,提出了工艺及设备的改进方向.     

镁热法生产海绵钛还原过程强制散热研究

针对镁热法生产海绵钛还原过程散热慢和还原周期长的问题,采用强制散热的方法,考察了海绵钛散热量对海绵钛质量、四氯化钛加料速度和还原生产周期的影响。结果表明,强制散热是海绵钛还原中期降低反应釜壁温度、提高海绵钛质量和四氯化钛加料速度、缩短还原周期的有效方法。     

微波场中FeNb2O6碳热还原反应研究

将微波加热与FeNb2O6碳热还原特性进行结合,探究FeNb2O6在微波场中的还原反应.利用微波热重分析研究了温度、粒度和配碳量等因素对微波碳热还原FeNb2O6反应速率的影响,同时对微波场中FeNb2O6碳热还原反应进行动力学分析.研究结果表明:在微波加热的情况下,FFeNb2O6具有良好的升温特性;相较于常规加热,...     

微波辅助碳热还原法制备氮化钒

以微波辅助碳热还原法对五氧化二钒进行还原氮化。测定了炭黑、活性碳和石墨作为还原剂的混合物料在微波场的升温曲线,并采用热重分析法考察了微波场中不同输入电流对物料还原程度的影响。结果表明,3种还原剂中炭黑的吸波性能和还原性能最佳,在输入电流为16 A、微波辐照时间105 min时,炭黑物料的还原度为0.96,当辐照时间延长至120 min时,氮化反应迅速,此时样品氮含量为16.36%。     

镧热还原氧化钐还原蒸馏过程的温度场分布

建立了镧热还原氧化钐温度场的简化数学模型,通过对该模型的计算,得到了还原反应过程中温度场的分布图像.     

微波作用下高磷铁矿提铁脱磷的实验研究

进行了微波作用高磷鲕状赤铁矿煤基碳热还原提铁脱磷的实验研究。从热力学和动力学方面研究了微波强化高磷铁矿提铁脱磷的作用机理,探讨了微波场中高磷铁矿提铁脱磷的影响因素和工艺条件。结果表明:微波可以加快铁矿石碳热还原反应速率,强化提铁脱磷效果;高磷铁矿在微波场中碳热还原,再经细磨和磁选,其脱磷率可达87.8%,收铁率可达90%。     

镍铁矿热炉熔炼过程中的多物理场耦合

建立了一个三维多物理场耦合模型,揭示矿热炉运行过程中电磁、温度、化学反应间的相互作用机理.该模型不仅将电磁理论、多相流动、传热、还原反应整合到统一的计算框架中,还通过用户自定义函数(UDFs)将电弧热、焦耳热和化学反应热加入到能量方程源项中.研究了不同电极插入深度下的熔池温度分布,并分析了熔池不同位置处的还原反应量.结果表明：随着电极插入深度的增加,熔池温度不断升高;在磁场作用下,熔池底部温度分布均匀;熔池区内氧化镍比铁氧化物还原更彻底,而坩埚区内镍铁氧化物均被彻底还原;当电极插入深度为2.1 m和2.2 m时,有助于提高炉料温度,适用于升温阶段;当电极插入深度为2.0 m时,炉料温度和铁氧化物的还原量更为均衡,适用于稳定熔炼阶段.     

镧热还原氧化钐过程中热效应对温度分布的影响

讨论了大容积真空碳管炉中镧热还原氧化钐温度场的数学模型,通过对该模型的计算,得到了还原反应过程中温度场的分布图像.     

含钒钛铁矿球团还原过程中微观结构变化

在实验室模拟高炉条件下研究了含钒钛铁矿球团的还原过程,采用X射线衍射仪测定含钒钛铁矿球团在不同还原温度下的物相组成,通过光学显微镜和扫描电镜观察含钒钛铁矿球团还原过程中微观结构变化,并结合能谱分析仪研究氧化物中不同元素的分布状况.含钒钛铁矿球团在还原过程中出现的铁钛分离现象会影响含钒钛铁矿球团的还原性,形成的高钛含量钛铁晶石会增加铁氧化物还原难度.高温时形成的密实金属铁球壳会阻碍内部氧化物的还原,导致还原停滞,从而造成含钒钛铁矿球团高温还原性较差.当内部熔融物滴下时,会提高高炉下部氧势,有利于减少Ti(C,N)的生成.      

树脂法提纯黄金工艺

本发明是一种树脂法提纯黄金工艺，涉及金泥的处理技术。它是将金泥经硫酸除杂，再经硝酸除银，最后将硝酸渣加入溶解反应釜，再将王水加入溶解反应釜，当反应结束后调整pH值1～3后用真空泵过滤，滤渣为回收金。滤液压入除杂树脂柱后流入还原反应釜，再加入亚硫酸钠还原，还原后用真空泵过滤，并用热水多次洗涤金粉，烘干冶炼铸锭。     

260t/h大型干熄焦炉环形烟道内墙应力场

 为了找到抑制干熄焦内墙损坏的措施，以260 t/h大型干熄焦炉环形烟道内墙为研究对象，采用热应力顺序耦合法，就温度场、装焦量及三角形挡墙对环形烟道内墙变形量的影响进行分析。结果表明，在温度场作用下，内墙的变形量较无温度场时大幅增加，说明热应力是造成内墙变形的主要因素；无论在冷态还是热态条件下，环形烟道内墙变形量都会随着干熄炉内装焦量的增加而逐渐增大；无温度场情况时，三角挡墙对内墙变形的抑制作用更加明显；有温度场作用时，当焦面高度达到4 m以上时三角挡墙对内墙变形有明显的抑制作用。三角挡墙最为合理的高度为1.0 m。     

Fatigue and fracture of high-alloyed steel specimens subjected to purely thermal cycling

High-alloyed steel specimens subjected to hundreds of thermal cycles (heating up in a furnace to about 900 °C, quenching in water, resting in air) are considered. Contrary to standard “low-cycle fatigue” tests with a cyclically varying applied mechanical load, the driving “force” is a cyclic temperature field with self-equilibrating residual stress states. Despite the cyclic character of this temperature field and no applied load, a significant monotonie change of the shape and metallurgical structure of the specimens can be observed depending strongly on the material and the initial geometry. Precipitations along the grain boundaries and remarkable residual stress states are responsible for internal cracks and damage. An experimental program is reported, and metallurgical and mechanical interpretations are presented.     

Internal friction of duralumin in a DC magnetic field

As a result of an experimental study of the low-frequency (10 Hz) internal friction of D16 duralumin in dc magnetic fields with an induction 0 ≤ B ≤ 0.9 T at a temperature of 20°C, a maximum in the field dependence of the internal friction is detected in a field B ≈ 0.45 T. A numerical analysis of the experimental data is carried out using the Friedel amplitude dependence of the internal friction, which takes into account thermal displacements of dislocations in a crystal with impurities. The Friedel amplitude dependence is modified using the concept of the influence of a magnetic field on the probability of singlet-triplet electron transitions in the dislocation core-paramagnetic center (defect) system. Duralumin is used as an example to show that the modified Friedel dependence provides satisfactory agreement of the calculated data and the experimental data. It is concluded that the sensitivity of the low-frequency internal friction of D16 duralumin to a dc magnetic field measured at 20°C is due to the fact that mobile dislocations overcome impurity atoms of paramagnetic elements, in particular, titanium, because of thermal fluctuations. Internal friction can be used to determine the numerical values of the parameters characterizing the mechanical properties of metallic paramagnets in a dc magnetic field.     

双辊铸轧热变形及热应力的数值模拟

结晶辊内部结构非常复杂,受热发生变形后,辊表面形状变得不规则,因此研究结晶辊温度场、热应力及热变形,掌握其分布规律,对于控制结晶辊的变形,得到均匀的铸带具有重要意义.以结晶辊为主要研究对象,采用热结构直接耦合方法计算结晶辊的温度场、热应力和热变形,为结晶辊的设计提供参考.结果表明,选用Be-Co-Cu作为结晶辊材质,辊转动30 s后,辊外表面温度和最大等效应力保持稳定,最高和最低温度分别为198和449℃,最大等效应力为1041 MPa;转动300 s后,辊内部温度及变形达到稳定状态,辊外表面径向位移都在0.4～0.5mm之间.通过对比Be-Co-Cu材质和钢材质的温度和最大等效应力,得出Be-Co-Cu材质更适合于制造双辊的结论.     

公司治理中内部审计的研究

面对企业外部环境的快速变化，必须对内部审计以新的定位和认识，并顺应公司治理发展需要，转换审计职能，拓展内部审计领域，改进内部审计技术，提升内部审计价值。     

Formation of the thermodeformational properties of Mn-Cu-based alloys having the two-way shape memory effect

The specific features of the thermodeformational behavior of Mn-Cu-based alloys with the two-way shape memory effect are revealed, and their connection with the diffusionless fcc → fct phase transition and the forming structure is discussed. The mechanism of the reversible thermal deformation caused by directed internal stresses is considered. The factors that affect the temperature interval of the highest thermal sensitivity and the value of reversible and specific thermal deformation are found, and the possibilities of their change by additional alloying and heat treatment are studied.     

面向风电消纳的铝电解槽瞬态温度场的波动特性研究

针对铝电解系列消纳风电过程中电流波动对热场作用过程不明确的现状,应用电热场瞬态强耦合模型对某420kA大型铝电解槽在一个完整消纳周期内的热场进行研究。分别针对消纳电流为设计电流的2%、5%和10%三种情况,消纳持续周期为2h,恢复周期为6h,计算铝电解槽温度场的瞬态变化特性。结果表明,槽内各区域的温度均随着强化幅度的增加而增加,变化最大的区域为熔体区;越靠近熔体区域的部分,温度的变化幅度越大;而除导杆、钢爪外,越靠近槽壳表面部分,温度的变化幅度越小。在电流恢复至正常值期间,电解槽温度下降速度缓慢,需要比较长的时间才能恢复到正常值,故铝电解槽电流波动幅度不宜太大。     

Mathematical model of the thermal processing of steel ingots: Part II. Stress model

A mathematical model has been developed to predict the internal stresses generated in a steel ingot during thermal processing. The thermal history of the ingot has been predicted by a finite-element, heat-flow model, the subject of the first part of this two-part paper, which serves as input to the stress model. The stress model has been formulated for a two-dimensional transverse plane at mid-height of the ingot and is a transient, elasto-viscoplastic, finite-element analysis of the thermal stress field. Salient features of the model include the incorporation of time-temperature and temperature-dependent mechanical properties, and volume changes associated with nonequilibrium phase transformation. Model predictions demonstrate that the development of internal stresses in the ingot during thermal processing can be directly linked to the progress of the phase transformation front. Moreover, the low strain levels calculated indicate that metallurgical embrittlement must be very important to the formation of cracks in addition to the development of high tensile stresses. B. G. THOMAS, formerly a Graduate Student at the University of British Columbia     

Effect of phase formation in the Mo-Ni system on the rate of change of the thermal conductivity of the interface

The formation and growth of new phases in a film (coating)-substrate system is shown to be diagnosed from a change in the shape of the oscillating component of the temperature field on the sample surface that is induced by the radiation of a periodic pulsed laser. For the Mo(10 μm)-Ni(5 mm) system, a change in the coefficient of correlation of the shape of a pyrometric signal and the relative change in the thermal conductivity of the interface are studied experimentally and theoretically during thermal annealing and 9-MeV electron irradiation.     

内铸钢管水冷炉喉钢砖温度场和应力场计算

 利用数值模拟的方法研究了边缘煤气流过分发展对炉喉钢砖的影响。建立了水冷式炉喉钢砖模型,计算了其在不同煤气温度下热面的温度分布和应力差异以及水管和内部耐材表面的最高温度和最大应力。结果发现,煤气温度从500℃升高至1100℃,钢砖的热面最高温度上升约500℃,热面高温区域应力迅速增大,导致钢砖破损加剧,因此需借助布料等上部调节手段,控制边缘煤气流过分发展,防止形成边缘“管道”,确保钢砖正常、稳定地工作。