纯银自然时效的软化特性

研究了纯度为99.99％(A_1)和99.9％(A_2)银材的时效软化行为,讨论影响银材时效软化速率的诸多因素。实验指出在90天的时效周期内,只有当ε=0～99％在0℃或者当ε≤40％在20～50℃条件下A_1和A_2的机械性能相对稳定。银材的时效软化是由于其内部结构产生再结晶组织所致。     

不同轧制加工率下纯Ag的再结晶温度研究

对不同轧制加工率下所制备的纯银带材进行退火处理,分析不同加工率下纯银的再结晶温度和显微组织。结果表明:轧制加工率的大小直接影响纯银的再结晶温度。加工率越大,再结晶温度越低。当加工率为90%时,退火温度为100℃时纯银即发生再结晶转变,组织呈等轴晶;当加工率为10%时,退火温度增加至400℃时纯银才可发生完全再结晶。     

加工率及退火温度对纯Ag硬度的影响

对不同加工率和退火温度下纯银的硬度进行检测,并分析了其显微组织。结果表明:不同加工率下,随退火温度升高纯银的硬度逐渐降低,但降低的速率并不一致;当加工率低于50%时,退火温度在200℃时硬度下降最快,而当加工率高于70%时,退火温度在100℃时硬度下降最快。     

微量元素Al和Mn对银带材性能的影响

为解决银材自然时效软化的问题，存99．999％Ag中添加0.004％A1和0．003％Mn(按质量)制成纯度为99．99％的Ag材，实验表明，采用变形率为90．90％所制备的银材，在25℃温度下，自然时效365d，其强度σb=370MPa，硬度HV=1030MPa保持稳定不变，有效地抑制了纯银材自然时效80d，其力学性能便大幅度下降的问题。     

处理温度对电沉积银石墨复合镀层接触电阻的影响

使用电沉积方法在铜基表面分别制备了纯银层、银石墨复合镀层和纯银/银石墨复合镀层,研究了处理温度对3种镀层接触电阻的影响。研究表明,室温时相同力矩下复合镀层与纯银镀层相比具有更低的接触电阻,5 N·m力矩下纯银镀层、银石墨复合镀层和纯银/银石墨复合镀层的接触电阻分别为24.9、19.4和19.9μ?。25~240℃处理后,3种镀层的接触电阻变化不大。240~600℃处理后,纯银镀层和纯银/银石墨复合镀层的接触电阻随温度增加而逐渐增大,600℃处理后5 N·m力矩下分别为54.3和42.6μ?;银石墨复合镀层的接触电阻随温度增加而迅速增大,480℃处理后已达125.5μ?,镀层表面出现严重"脱皮"现象。     

科技动态

金属钛镀前的活化金属钛镀前可以用下列方法活化:A、用细晶粒的刚玉(Al_2O_3)的湿喷丸.B、用含氟化物的溶液在室温下浸蚀几分钟.C、在铬酸、氢氟酸、砷和锑化合物溶液中,在35～100℃下,活化15～50分钟.具有附着力超过70N/mm~2的镀层可以用这种处理手段取得.在电镀之前,这个活化表面也可以保存几天、附着力不会减弱.     

有色金属材料焊接技术实用讲座(六)——纯银的焊接

纯银和银合金广泛应用于工业中,例如制造银钎焊料;某些化工装置上用以制造耐腐蚀容器及纯银复合板;在电子工业、实验设备、高真空技术中亦获得一定的应用。 1. 纯银的基本性能及焊接特点 (1)纯银的基本性能纯银以丝、板、带、管子等形式供应,其纯度在99.9～99.99％间,主要杂质有铅、铁、鈊、锑等,铁的含量小于0.05％,其余杂质的含量均小于0.003％。纯银的塑性优良,它可轧制成厚度为0.00001～0.00025mm的银箔。纯银的物理性能及机械性能列于表1。     

微波场中不同配碳量钛精矿的吸波特性

采用微波谐振腔微扰法测定了碳质还原剂和钛精矿混合物料的吸波特性,研究了碳质还原剂配入钛精矿不同比例时混合物的吸波特性与材料的复介电常数（ε″）、微波场内热源强度p的关系。分析结果表明：当粒度为147～175μm时,钛精矿的吸波特性优于椰壳碳、焦碳和无烟煤的;且通过比较复介电常数的大小确定了椰壳碳和钛精矿最佳配比为20%,焦碳和钛精矿最佳配比为14%,无烟煤和钛精矿最佳配比为5%;并在此配比条件下得到了ε″和p的最大值。     

工业纯钛ECAP温变形的力学性能及热稳定性

采用两通道夹角φ=90°,外圆角ψ=20°的模具,成功实现了工业纯钛BC方式6道次ECAP温变形,累积等效真应变达到约6.3,制得ECAP温变形试样后,对各道次ECAP温变形后的工业纯钛进行压下量为55％的冷轧变形.同时,观察分析了变形试样的显微组织及性能,并对各道次ECAP温变形试样的热稳定性进行研究.结果表明,经过6道次ECAP变形后,工业纯钛的抗拉强度达到760MPa,伸长率为40％.当退火温度低于400℃时,ECAP变形试样的组织变化不大,显微硬度下降缓慢;当退火温度高于400℃时,由于发生了再结晶,显微硬度显著下降.     

电沉积时间和电流对熔盐电沉积钛镀层Ti含量和耐腐蚀性的影响

研究了沉积电流和沉积时间对熔盐电沉积钛镀层Ti含量及其耐腐蚀性的影响。结果表明,在800℃下,当沉积时间1h,沉积电流1.5A的条件下,碳钢表面沉积层中钛含量最高,并且钛沉积层表面形貌均匀、致密。试样的耐腐蚀性与沉积层中的钛含量正相关,即当沉积时间为1 h,沉积电流为1.5 A的条件下获得的试样耐腐蚀性最佳。另外,沉积层具有较低含量的钛金属,能明显提高碳钢基体的耐腐蚀性。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。     

Acta Metallurgica Sinica(English Letters)

<正>Copyright Information For Authors As soon as an article is accepted for publication,authors will be requested to assign copyright of the article(or to grant exclusive publication and dissemination rights)to the publisher(respective the owner if other than Springer).This will ensure the widest possible protection and dissemination of information under copyright laws.More information about copyright regulations for this journal is available at www.springer.com/40195.     

Acta Metallurgica Sinica(English Letters)

<正>Copyright Information For Authors As soon as an article is accepted for publication,authors will be requested to assign copyright of the article(or to grant exclusive publication and dissemination rights)to the publisher(respective the owner if other than Springer).This will ensure the widest possible protection and dissemination of information under copyright laws.More information about copyright regulations for this journal is available at     

Yilin Hydraulic Group Harbin General Hydraulic Machinery Works Co.,Ltd.

正Harbin General Hydraulic Machinery Works Co.,Ltd.of Yilin Hydraulic Group is the most professional production base of large-scale metallurgy oil cylinder and oil machinery cylinder in the Northeast of China.The main products include metallurgy cylinder,swell-shrink cylinder,rotating injection device,lifting cylinder,main lifting jack,front lifting jack,engineering oil cyl-     

Weihai HHH Mach. & Elec. Group

正Weihai HHH Mach.Elec.Group is the most technical company focusing on Power transmission and Hydra-controlling.HHH has the ability of developing and testing of complete sets of transmission system with relevant technical training.HHH provide efficient,excellent cost-effective power transmission system and intelligent electric fluid transmission and control system to OEM customers,who are     

Letter of Congatutulation

正I take great pleasure in congratulating CHINA FOUNDRY journal on its 10th anniversary.The CHINA FOUNDRY journal started ten years ago.Since its inaugural,China has seen exceptional growth in the Castings Sector and rapid development in Machinery Industry.The journal is becoming an important communication platform for experts     

The 9th China International Diecasting Congress& The 1st International Symposium on Nonferrous Alloys and Special Casting Technologies held in Shanghai

The 9th China International Diecasting Congress and the 1st International Symposium on Nonferrous Alloys and Special Casting Technologies （ISNASCT） were successfully held in Shanghai on July 19-22, 2014. Both events were jointly sponsored by Chinese Mechanical Engineering Society, Die Casting Commission of World Foundry Organization and Non-Ferrous Materials Commission of World Foundry Organization, and organized by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） and China Productivity Promotion Center of Foundry Industry.     

Dangyang Iron Tower——Corrosion-resistant cast iron casting

<正>Made in 1061 A.D.(North Song Dynasty)Height:17.9m,weight:53.3tThe Dangyang Tower,located outside of the Yuanquan temple in Dangyang county of Hubei province,is the tallest ancient iron tower in China.On the base,there are sculptures of eight Herculean men supporting the