Investigation and Development of Technological Parameters for the Vacuum Melting of Corrosion-Resistant Refractory Nickel Alloys

Metallurgist - We perform investigations aimed at the development of the main technological parameters of melting of high-chromium corrosion-resistant refractory nickel alloys in vacuum induction...     

单嘴精炼装置真空室内卷渣水模型研究

本文针对长城特殊厂单嘴精炼装置进行了真空室内加渣精炼的卷渣水模型研究。在试验的基础上，首先讨论了真空室内卷渣现象的工艺过程，然后进一步得出了临界吹气量的表达式。研究结果为工业性生产进一步提高钢的质量打下了基础。     

Behavior of Rare-Earth Metals in Vacuum Melting and Directional Solidification of Nickel Superalloys

The interaction of the nickel melt containing REMs (Y, Ce, and La) with the ceramic material of a melting crucible (Al₂O₃, MgO ? Al₂O₃, Y₂O₃) during vacuum melting and with a mold (Al₂O₃) during directional solidification of has been detected experimentally. The REM concentration in a metal decreases as a result of holding of an REM-containing melt in a ceramic crucible or a mold. This should be taken into account to achieve the optimal required REM content in alloys.     

Industrial Electron-Beam Equipment for Deposition of Protective Coatings: Overview

Powder Metallurgy and Metal Ceramics - The current development of industrial electron-beam equipment for the deposition of protective coatings on gas turbine blades by high-speed electron-beam...     

Refining Complexly Alloyed Molten Nickel from Sulfur Impurity to Less than 1 Ppm During Vacuum Melting

Metallurgist - The possibility is established of reducing the sulfur content in cast nickel superalloys to less than 1 ppm (0.0001 wt.%) with addition to alloys of an increased amount of rare earth...     

Vacuum Refining of Molten Silicon

Metallurgical fundamentals for vacuum refining of molten silicon and the behavior of different impurities in this process are studied. A novel mass transfer model for the removal of volatile impurities from silicon in vacuum induction refining is developed. The boundary conditions for vacuum refining system??the equilibrium partial pressures of the dissolved elements and their actual partial pressures under vacuum??are determined through thermodynamic and kinetic approaches. It is indicated that the vacuum removal kinetics of the impurities is different, and it is controlled by one, two, or all the three subsequent reaction mechanisms??mass transfer in a melt boundary layer, chemical evaporation on the melt surface, and mass transfer in the gas phase. Vacuum refining experimental results of this study and literature data are used to study the model validation. The model provides reliable results and shows correlation with the experimental data for many volatile elements. Kinetics of phosphorus removal, which is an important impurity in the production of solar grade silicon, is properly predicted by the model, and it is observed that phosphorus elimination from silicon is significantly increased with increasing process temperature.     

真空感应炉熔炼过程供电制度的优化

通过对3～6t真空感应炉熔炼过程的能量需求与损失的系统分析与计算，利用热电平衡规律，推导得出真空感应熔炼过程能量平衡模型，并提出各熔炼阶段合理的电能供给制度。采用优化的供电制度在3～6t真空感应炉中通过所冶炼的38炉300M钢(％：0．4C，1．10Mn，1．64Si，0．29Co，1．85Ni，0．4Mo)的结果可得，冶炼电耗降低41 kWh／t，生产效率提高8．3％，Mn收得率提高1．6％，Cr收得率提高0．25％，并提高了坩埚使用寿命。     

RH真空精炼炉脱气工艺分析

结合生产实际数据,分析了RH真空脱气工艺过程。如要求[H]≤1.8×10-6,需真空处理9min;当要求[H]≤1.5×10-6时,冬、春季节RH处理时间为≥11min,夏季则为≥12min,秋季应为≥13min;RH脱氮率约为23%,且在脱气超过8min时RH脱氮出现拐点,延长真空处理时间对脱氮影响不大。     

紫铜及其合金熔炼的覆盖剂

本文着重对熔炼紫铜及铜合金时,铜液中的氢及夹杂物不能完全排除的主要原因进行了分析。采用石墨粉覆盖法熔炼铜及合金,经熔铸实践验证效果良好。基本上改变了过去铜液内含氢高,夹杂物多的状况。铜板的成材率在原有基础上提高了5—8%,取得了较好的技术经济效果。     

Vacuum Evaporation of Pure Metals

Theories on the evaporation of pure substances are reviewed and applied to study vacuum evaporation of pure metals. It is shown that there is good agreement between different theories for weak evaporation, whereas there are differences under intensive evaporation conditions. For weak evaporation, the evaporation coefficient in Hertz-Knudsen equation is 1.66. Vapor velocity as a function of the pressure is calculated applying several theories. If a condensing surface is less than one collision length from the evaporating surface, the Hertz-Knudsen equation applies. For a case where the condensing surface is not close to the evaporating surface, a pressure criterion for intensive evaporation is introduced, called the effective vacuum pressure, p _eff. It is a fraction of the vapor pressure of the pure metal. The vacuum evaporation rate should not be affected by pressure changes below p _eff, so that in lower pressures below p _eff, the evaporation flux is constant and equal to a fraction of the maximum evaporation flux given by Hertz-Knudsen equation as 0.844 $ \dot{n}_{\hbox{Max} } $ . Experimental data on the evaporation of liquid and solid metals are included.     

V-Ti-Fe储氢合金的真空精炼

采用真空感应炉对金属热还原法制备的V-Ti-Fe合金进行精炼,考察金属铈对精炼效果的影响。结果表明,铈可有效脱除合金中的氧杂质,减少合金内的富钛相和硅偏聚相,降低合金的成分偏析,促进合金的吸氢活化。随铈用量的增加,脱氧效果也逐渐增强,储氢容量得到提升,当铈添加量达到合金用量的5%时,氧含量降到了0.05%,最大吸氢量和有效放氢量分别达到3.36%和1.85%。     

钒铝合金真空精炼试验

对钒铝合金的真空精炼进行研究,并对合金的物相进行表征。结果表明,控制真空精炼时间、真空度和过热度等可使钒收率和产品质量得到较大提高,产品符合德国GfE公司宇航级标准要求。     

VD真空精炼温度预报模型

开发了较为完善的VD终点温度在线预报系统。采用MINITAB软件确定影响VD过程温降的主要因素为抽真空时间、保压时间、吹氩时间、非真空时间、VD搬入钢水的过热度、LF处理时间以及转炉出钢至VD初始测温之间的钢包运输时间。应用神经网络方法对VD处理终点的钢水温度进行在线预报,系统在线连续预报了95罐,预报温度与实际测量温...     

镁锂合金的组织结构及熔炼加工

镁锂合金因其优异的性能正在受到航空航天及兵器工业的广泛重视，而我国对镁锂合金的研究还很少。镁锂合金生产的难点在于熔铸工艺，只有严格控制工艺条件才能生产出合格的产品。镁锂合金的成分不同，合金中存在的相也不同，需要确定不同的加工工艺。     

电解精炼-区域熔炼法制备高纯铟的研究

采用电解精炼 区域熔炼法 ,获得了 99 9999%高纯铟。从理论上探讨了采用区域熔炼法进一步提高铟的纯度的原理。采用In2 (SO4 ) 3～H2 SO4 体系 ,控制电解液pH为 2～ 3 ,In含量 80～ 10 0g·L- 1 ,电流密度 80～ 10 0A·m- 2 ,温度为 2 0～ 3 0℃ ,进行一次电解精炼 ,可得到纯度接近 99.999%的高纯铟。以电解精炼铟为原料进行区域熔炼 ,对熔体进行磁力搅拌 ,控制较低的区熔速度 ,可获得 99.9999%以上的高纯铟     

稀有金属的半微量相平衡与萃取平衡实验装置

设计了一套包含恒 水槽、转动载样系统和微量取样的半微量相平衡与与萃取平衡的实验装置,并测定了几种盐的溶解度,与文献报道结果一致。     

铝合金热轧板锭熔铸技术及设备

本文概述了近年来铝合金热轧板锭的熔铸设备和熔铸技术的发展和最新成就，重点介绍晶粒细化、熔体净化、检测及铸造新技术，为国内铝板带企业跟踪国际铝合金板锭熔铸技术、开展技术攻关和进行技术创新提供有益的参考。     

Fe-Al基金属间化合物的电渣重熔工艺

通过适当的非真空冶炼+电渣重熔工艺,制备了含Cr的Fe₃Al基金属间化合物合金.实验发现,选择适当的热输入工艺参数,电渣重熔过程极大地降低了Fe₃Al基金属间化合物合金中的S,O,H,P等杂质元素的含量,改善了析出相的大小与分布.铸锭具有良好的热加工性能,经锻造和中温热机械处理后,纵向室温延伸率分别超过8%和10%,屈服强度超过400MPa,断裂强度达到700 MPa,力学性能与同类真空冶炼大体积材料的性能相当.     

Hybrid Neural Network Model for RH Vacuum Refining Process Control

A hybrid neural network model, in which RH process (theoretical) model is combined organically with neural network (NN) and case-base reasoning (CBR), was established.The CBR method was used to select the operation mode and the RH operational guide parameters for different steel grades according to the initial conditions of molten steel, and a three-layer BP neural network was adopted to deal with nonlinear factors for improving and compensating the limitations of technological model for RH process control and end-point prediction. It was verified that the hybrid neural network is effective for improving the precision and calculation efficiency of the model.