反重力铸造液面加压系统的自调整比例因子模糊控制

液面加压系统担负着控制合金液上升、充型、结壳、保压等重要任务,其控制精度对反重力铸造铸件的质量具有重要影响。常规模糊控制仅用一组恒定不变的输入、输出比例因子,难以保证被控全过程处于最佳控制状态,在反重力铸造液面加压控制系统中的应用受到限制。将模糊控制中输入与输出比例因子在不同压力偏差范围内进行分段调整:压力偏差较大时,增大输出比例因子,加快动态响应;压力偏差较小时,增大输入比例因子,减少稳态误差。试验结果表明,该液面加压控制系统具有较好的静态性能和鲁棒性,实际压力曲线的跟踪性能良好,升液、充型阶段压力平稳,满足了反重力铸造的控制要求。     

大洋富钴结壳的超声测厚

针对载人潜水器水下作业时需对富钴结壳厚度进行实时原位检测的问题,设计了富钴结壳的超声测厚系统,分析了富钴结壳的物理特性及测厚原理,设计了基于ARM处理器芯片测厚系统硬件的方案,该方案根据富钴结壳采样信号的处理,提出了针对富钴结壳的峰值检测算法;最后,在实验室搭建了模拟测试装置,对样品进行了检测。结果表明,利用峰值检测算法可有效识别富钴结壳样品的顶部回波与底部回波时间,并计算出被测结壳的厚度,且准确性高。     

深海矿产资源开采方法

20世纪后期,＂国际海底区域＂活动从多金属结核单一资源向富钴结壳、热液硫化物等多种资源扩展。一些专家根据新的深海矿资产资源的赋存特性和需求,认为富钴结壳和热液硫化物将早于多金属结核而进行商业开采,面向富钴结壳和热液硫化物的深海采矿技术成为一些工业发达国家的研究热点。作者以富钴结壳的开采为例,向大家详细介绍CLB法、ELB法等主流开采方法。     

论侧插自焙电解槽炉底结壳的形成及处理

本文阐述了电解槽炉底结壳的分类、组成以及对电解生产的影响，论述了侧插自焙电解槽炉底结壳的形成及处理方法。     

湿法结壳工艺探讨

一、湿法结壳工艺机理的探讨 1.有关机理的提法 在第43届国际铸造年会上,我国代表宣读了湿法结壳工艺的论文。文中对结壳机理部分的描述如下: “我们通过试验和工厂实践发现了浸涂浆料的不同表现与干燥时间的关系如图1所示。     

振动激发金属液形核结壳过程的数值模拟

振动激发金属液形核技术可以有效提高铁素体不锈钢熔体中的等轴晶率,但由于其自身的激冷作用易在晶核发射器的表面形成结壳,致使该技术失效。为解决该缺陷,本文通过FLUENT软件模拟该技术在600、700、800Hz三种振动频率下对结壳的影响。结果表明,600、700、800 Hz三种频率下在垂直于振动方向的结壳时间分别为8.120、9.020、9.620 s。增大振动频率可以延长结壳时间,三种频率中800 Hz为最佳振动频率。     

氧化铝电解时结壳及槽底渣层的形成和性质

在试验室条件下研究形成的结壳时曾发现,结壳的密度随着添加的氧化铝中α-Al_2O_3含量的增加而变大;但是,结壳在冰晶石-氧化铝熔体中的寿命(维持时间)和稳定性却降低。氧化铝中细粒部分(<45μm)的增加也会引起结壳密度增大;其他参数如电解质的组成和温度也发生了变化。     

铝电解槽多相夹杂物形成的特点及其性质

在电解生产铝和精炼铝时,除铝和电解质两个不相混合的液相之外,还存在着相当数量的多相固体夹杂物:铝电解槽的槽帮结壳,槽底结壳与《沉淀》;铝精炼槽的槽帮结壳漂浮物     

85kA预焙槽炉底结壳形成的原因与对策

本文简单分析了85kA中间点式下料预焙槽炉底结壳形成的原因,提出了标准化和规范化的电解槽作业制度以及处理炉底结壳的建议,达到了节能降耗、提高电流效率的目的。     

中间下料预焙槽槽底结构改进

本专利方法介绍了一种改进式中间下料预焙槽槽底结构。中间下料预焙槽随着操作进行,沿槽大面中心轴的阴极纵断面形成三角形槽底结壳。过去的电解槽形成此种槽底结壳实属不可避免。而且在槽底结壳上部还覆盖着一层由氧化铝和电解质混合而成的糊状沉积     

Cu/Ag核壳复合粉末的制备与表征

综合直接镀银法与葡萄糖浴法两种工艺,在微米级Cu粉的表面得到了包覆完整的Ag层.通过对Cu/Ag核壳粉末的致密化处理,使Ag层中的孔隙大大减少,改善了复合粉的抗氧化性,同时提高了Cu核与Ag层之间的结合强度.用x射线衍射法、扫描电子显微镜观察和热重分析的方法对铜.银双金属粉进行了表征.用本工艺得到的Cu-Ag核壳粉末在790℃以下具有良好的抗氧化性.     

135KA预焙铝电解槽槽壳修复技术

提出了 13 5KA预焙铝电解槽槽壳的变形破损的修复方案 ,并分析此修复技术的经济效益     

The effect of casting conditions on the formation of longitudinal surface crack in the beam blank caster

To understand the effects of casting conditions on the formation of longitudinal surface crack, the crack morphology of over 2000 charges at scarfed beam blanks were investigated. The results whow that the most sensitive crack susceptibility range of carbon contents lie in the 0.12–0.13 wt.% range. This was due to the effect of shell irregularity between mold surface and solidified shell withdrawn by δ-γ transformation and the embrittlement phenomena by liquid film of soluble elements such as phosphorous and sulfur at the dendrite interface. It was found that the increase of crack formation is attributed to the increase of phosphorous and sulfur contents segregated at the dendrite interface. The increase of crack formation with increasing Phosphorous and Sulfur contents is due to the enlargement of the ΔT range, which is defined as the temperature difference between LIT (liquid impenetrable temperature) and ZDT (zero ductility temperature). The effect of casting speed on crack formation shows a linear relationship. As casting speed is increased, the solidified shell had little time to grow and the width of shell became smaller. As, the heat flux from the thinner shell increased, the thermal strain was increased, increasing crack formation.     

Formation of Mg,Al-hydrotalcite conversion coating on Mg alloy in aqueous HCO3/CO3 and corresponding protection against corrosion by the coating

An environmentally clean method is studied for synthesizing a conversion coating on Mg alloy in aqueous at 50 °C. A precursor layer was firstly formed on AZ91D sample. The precursor layer transformed into a crystallized Mg,Al-hydrotalcite when the sample was continuously immersed in the bath until the bath changed from acidic to alkaline. A rapid conversion treatment was, therefore, developed: it involved maintaining the pH under 6 for precursor layer formation and then increasing it to 11.5 to form crystallized Mg,Al-hydrotalcite coating. No corrosion spot on the Mg,Al-hydrotalcite-coated sample was observed after a 72-hour salt spray test.     

Synthesis and characterization of ZnSe/ZnS core/shell nanocrystals by aqueous reflux route

ZnSe/ZnS core/shell nanocrystals (NCs) with strong photoluminescence (PL) intensity and improved photochemical stability are synthesized through a simple water bath reflux route. Diffraction peaks can be indexed by zinc blend structure of ZnSe and ZnS. Transmission electron microscope (TEM) images reveal that each ZnSe NC (27 nm) is coated by a ZnS epitaxial shell. The ZnS shells are constitutive of crystalline and amorphous ZnS NC film with average thickness of 5 nm thick. The photoluminescence of ZnSe/ZnS core/shell NCs is also remarkably improved, which can be approved by the PL spectrum and laser-scanning confocal microscope test.     

Corrosion behavior of anodized AA‐6060 depending on the anodizing bath aging

The present work is concerned with the corrosion behavior of anodized AA‐6060 in chloride containing solutions. The anodic layers were produced with identical anodizing parameters but in an anodizing bath at different stages of bath aging or the time of use, respectively. The bath aging was monitored by the conductivity and was related to the consumed charge. The oxide layers were characterized by scanning electron microscopy (SEM)/electron dispersive x‐ray spectroscopy (EDX) and X‐ray fluorescence analysis. The corrosion behavior was characterized by a combination of electrochemical measurements (linear sweep voltammetry and electrochemical impedance spectroscopy) and corrosion tests (droplet and salt spray tests). It is shown in this paper that the kinetics of oxide formation, as well as the oxide composition, changes with ongoing bath aging. The corrosion protection of the anodic layers strictly depends on the time of use of the anodizing bath and decreases continuously with ongoing bath aging.     

高炉炉壳整体应力的计算

针对高炉炉壳各种复杂的开孔及受力情况，考虑作用在高炉炉壳上的各种负荷，推导出相应的应力计算公式，针对宝钢3号高炉投产初期及当前状态，将3号高炉有关数据带入相应的计算公式，计算得到3号高炉各段炉壳上的应力值。     

Causes and control of welding cracks in electron-beam-welded superalloy GH4169 joints

Welding joint of GH4169 alloy with a good formation was obtained. No macroscopic defects occurred in the joint. The weld had mainly a dendritic structure; the base metal was a solid solution of Ni, Cr, and Fe, and the strengthening-phase particles such as Ni₃Nb were dispersively distributed along the grain boundary. The average tensile strength of the joint reached 743.7 MPa, and the Vickers hardness of the weld exceeded HV 300. Because of the segregation of the low-melting compound Ni₃Nb at the grain boundary of the fusion zone, liquid cracks tended to occur as a result of welding stress. The formation of liquid cracks was inhibited by adding an alloying element, Mn, to the welding bath, because Mn diffused to the fusion zone and the high-melting phase Mn₂Nb formed, and thus the overall properties of the joint were improved.     

富氧底吹熔炼炉内气液两相流动的数值模拟

以某公司的富氧底吹熔池熔炼炉为原型,运用数值模拟的方法对炉内氧气铜锍两相流动进行三维瞬态模拟,研究炉内气泡主要参数、气含率分布规律、氧枪出口附近压力变化以及液面波动情况。并借助于高速摄像仪设备,对水模型实验中气泡形成、合并、变形及破碎过程进行研究,所得结果与模拟结果进行比较。结果表明:所建立的数学模型是合理的。氧气铜锍两相流动模拟结果表明,炉内气泡形成时间为0.12~0.25 s,生成频率为4~5 Hz,其短轴大小集中在3.5d~6.5d(d为氧枪直径尺寸);气泡停留时间为0.2~0.4 s,其在熔池内的平均上浮速度约为4 m/s;7°和22°氧枪出口气泡后座现象出现的平均频率分别为5 Hz和7 Hz,作用时间为0.06 s;高效反应区存在于熔池上部区域;气相搅动液相所形成的表面重力波在沉淀区传播的过程中,波幅衰减很快,当波传播到出渣口附近时,液面趋于静止。     

Cooling capacity of molten salts and alkalis containing water

Conclusions The method of cooling molten salts and alkalis in austempering and martempering by adding water to the bath at any temperature, which was developed and put into operation at the Gor'kovskii Metallurgical Plant, guarantees: 1) a constant temperature of the bath within limits of ±5°C; 2) constant amount of water in the bath, which increases the cooling capacity four to five times; 3) prevention of "aging" and elimination of the necessity of renewing the molten salts; 4) the use of austempering and martempering for tools, machine parts, rolled steel (including railroad rails) in place of ordinary oil-quenching to martensite with subsequent tempering.Gor'kovskii Metallurgical Plant. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 58–62, November, 1967.