烧结温度对石墨/铜复合材料微观组织与性能的影响

通过超声波分散结合机械球磨湿磨法对铜粉和石墨粉进行混料,利用放电等离子烧结（SPS）技术制备石墨/铜复合材料。运用扫描电镜（SEM）、X射线衍射仪（XRD）和电导仪等表征手段,研究了烧结温度对石墨/铜复合材料的微观组织与性能的影响。结果表明:超声波分散和机械球磨湿磨法可使石墨均匀分散于铜基体,并与铜基体形成良好的界面结合。当烧结温度从700 ℃升高到750 ℃,石墨/铜复合材料的相对密度、维氏硬度、抗压强度和电导率分别提高了1.6%,6.7%,11.3%和5.3%;当烧结温度从750 ℃升高至900 ℃时,其相对密度、维氏硬度、抗压强度和电导率均呈现下降趋势。当烧结温度为750 ℃时,石墨/铜复合材料组织均匀致密,平均晶粒尺寸约为6.4 μm,相对密度为96.3%,维氏硬度（HV_0.5）为60.7,抗压强度为422 MPa、电导率为86.7%IACS,综合性能较优。      

Insight into physicomechanical and tribological properties of copper galvanic coatings formed with the addition of electroerosion copper nanopowder

The results of studying the properties of copper galvanic coatings fabricated using an L1-210 v2 galvanic installation (Italy) using the bright copper plating electrolyte produced by 24 Karata (Moscow) and the addition of electroerosion copper nanopowder fabricated by the electroerosion dispersion (EED) method using copper wire scrap in distilled water are given. An original setup developed by the authors (RF Patent 2449859) was used for the EED of conductors. The friction coefficient and wear factor found when testing coatings using a Tribometer automated friction machine (CSM Instruments, Switzerland) indicate the absence of substantial distinctions in the wear resistance of the samples. Surface hardness tests of the sample were performed using a DM-8 automated microhardness tester according to the micro-Vickers method with an indenter load of 25 g by ten imprints with a free selection of the indentation point according to GOST (State Standard) 9450–76. The indenter loading time was 15 s. It is established that the microhardness of a copper coating with the addition of copper nanoparticles is 15% higher than that of steel substrate and the sample with a standard copper coating.     

Damping properties of sintered high-porosity materials based on powders and discrete copper fibers

Experimental relationships are established between the vibration decrement and the level of maximum cyclical deformations during the bending of sintered high-porosity materials based on powders and discrete copper fibers. The quality of interparticle contacts is evaluated in the sintered materials. Comparison of curves of the vibration decrement versus porosity for fixed maximum cyclical deformations indicated that the vibration decrement of all materials decreases with increasing porosity (within the range from 40 to 77%); however, it is appreciably greater vibration decrement of the matrix material (compact copper). Sintered high-porosity materials based on discrete copper fibers have the highest indicators of energy dispersion, especially at relatively high levels of maximum cyclical deformations as compared with sintered materials based on copper powders.     

Hydrogen reduction of copper bleed solution from an Indian copper smelter for producing high purity copper powders

A bench scale investigation on the hydrogen reduction of a highly acidic copper bleed solution to produce high purity copper powder is discussed in this paper. A titanium lined autoclave of 1 L capacity was used for this study. The parameters optimized on the bench scale were validated by performing hydrogen reduction of copper in a larger autoclave. Effect of various parameters viz., time of reduction, temperature of reduction, pressure variation, iron dose, volume of copper solution etc. were studied. Experiments were performed with synthetic and actual solution obtained from a copper plant. A 99% copper powder recovery is achieved by hydrogen reduction at a pressure of about 2400 kPa, reaction temperature of 453 K, stirring speed of 400 rpm for a reaction time of 2 h. The fine copper powder thus obtained had a good metallic lustre. Kinetics of reduction of copper was examined by drawing samples at different times and analyzing the percent copper reduction. The copper depleted solution was further purified with respect to the residual copper and can be processed for the recovery of nickel powder by hydrogen reduction.Properties of the copper powder obtained from the large-scale experiments from actual plant and synthetic solutions have been evaluated for powder metallurgical applications. The raw and annealed copper powders obtained from the synthetic copper solution were found to have an apparent density of 3.50 g/cm³, flow rate 35.6 g/min, hydrogen loss 0.2%, purity 99.8% and green density of 8.6 g/ cm³ while the powder from actual plant solution was found to have an apparent density of 3.59 g/ cm³, flow rate 46.0 g/min, hydrogen loss 0.6%, purity 99.4% and green density 8.6 g/ cm³. Thus, the copper powder produced by hydrogen reduction was found suitable for the application.     

铜精矿与铜冶炼渣的物相鉴别

按国别收集我国主要进口铜精矿及铜冶炼渣样品,采用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)、矿相显微镜、扫描电子显微镜(SEM)等多仪器联用的方法检测铜精矿、铜冶炼渣物相特点,判断两者是否存在显著的差异。结果表明,铜冶炼渣主要物相是硅酸铁,其颗粒表面有分布均匀、大小一致的气孔等外观特征。进口铜精矿的主要物相为硫化铁铜或氧化铜,颗粒表面平滑、不规则的分布一些形态各异的气孔。铜冶炼渣与铜精矿相比在物相及颗粒特征方面有明显的差异,可以作为鉴别依据。按比例在铜精矿中混入铜冶炼渣,制备含有不同含量梯度铜冶炼渣的混合样品11个,用上述4种检测手段进行鉴别,发现X射线荧光光谱仪无法确定样品中是否掺杂铜冶炼渣;电子显微镜、矿相显微镜、X射线衍射光谱仪可鉴别出铜精矿掺杂铜冶炼渣,检出限分别为1%、5%、10%。最终确定铜精矿与铜冶炼渣的物相鉴定方法为应用X射线荧光光谱仪初查,辅以X射线衍射仪、矿相显微镜及扫描电子显微镜找到铜冶炼渣的特征物相和颗粒。鉴别方法的确立达到了从源头堵住入境铜冶炼渣易名铜精矿和铜精矿掺杂铜冶炼渣闯关的目的,为海关监管和资源利用提供了技术支持。     

Oxidation rates of liquid copper and liquid copper sulfide

The kinetics of oxidation of liquid copper and copper sulfide were determined when the rate was controlled by the diffusion of the oxidizing gas to the melt interface. The method incorporated a capillary tube sample holder and the flux rate was measured by a quartz spring and cathetometer. The sample of copper sulfide was suspended from the balance in a tube furnace through which was passed a mixture of oxygen and argon gas. The oxidation of molten copper sulfide was found to proceed by the formation of copper followed by the formation of copper oxide. From the results, the diffusion coefficients of SO₂ and O₂ in argon were calculated over a temperature range of 1150° to 1350°C. The data compare well with the empirical equations for the diffusion of these gases. At lower temperatures, a different oxidation behavior is observed due to solidification of the sample.     

Structure formation during the sintering of powder steels alloyed with copper,chromium, and phosphorous

The process of structure formation during the sintering of powder steels alloyed with copper, chromium, and phosphorous was investigated. The microstructure of the materials, and distribution of alloying elements in the iron grains, were studied by the methods of electron and scanning electron microscopy. The effect of dispersion of the ferrochromium powder on its solubility in iron was examined.Kirov Factory for the Manufacture of Articles from Metal Powder. Translated from Poroshkovaya Metallurgiya, Nos. 5/6, pp. 56–62, May–June, 1995.     

高铜钼精矿湿法浸铜工艺试验研究

对某铜矿钼品位43.49%、含铜3.37%的钼精矿进行了湿法浸铜工艺试验。结果表明:酸浸除铜和化学氧化-酸浸除铜工艺,铜浸出率较低,钼损失率较高,未能提高钼精矿钼品位;CJ-1溶液除铜工艺铜浸出率高,钼损失率低,可达到提高钼精矿钼品位并降低含铜的目的。     

Determination of oxygen species in mechanically alloyed oxide dispersion strengthened copper

Abstract

The oxygen content in the process of the production of oxide dispersion strengthened copper by mechanical alloying was traced by carrier gas-hot extraction. First, the usual determination of the total oxygen content was carried out. Second, the analytical method was checked and modified with respect to the selection and detection of different oxygen species in the sample. Applying this analytical approach the relevance of various technological treatments (milling, heat treatment) on the oxygen concentration was evaluated.     

Entrainment behavior of copper and copper matte in copper smelting operations

In copper smelting, the loss of copper to the slag due to entrainment is largely influenced by the flotation of copper metal and/or matte in the slag phase. To evaluate this behavior, the surface tension of copper as a function of temperature and oxygen pressure and the interfacial tension of the copper-iron matte-slag system as a function of matte grade were measured. From the surface and interfacial tension values, the spreading and flotation coefficients of the copper, matte, and slag system were calculated. Ternary interfacial energy diagrams were also con-structed using these data. It is shown that matte droplets containing higher than 32 mass pct Cu will not form a film on rising gas bubbles when they collide in the slag phase. However, matte droplets will attach to gas bubbles upon collision and thus can be floated over the entire range of matte composition. Spreading of copper on bubbles is not possible at oxygen pressures between 10⁻¹² and 10⁻⁸ atm. Flotation of copper by gas bubble in slag is possible at oxygen pressure higher than 10⁻⁹ atm. However, it is feasible for rising matte droplets (attached to rising bubble) to trap and float copper irrespective of the matte grade.     

Microroughness evolution of the inner surface of copper pipes under drawing

The microroughness evolution of the inner surface of copper pipes under drawing is considered. The roughness parameter R _a is measured on the internal surface of pipes after pressing and drawing. It is revealed that R _a is minimal for hot-pressed pipes. Deformation by drawing to a logarithmic degree of deformation in 0.417 is accompanied by a rise in average parameter R _a from 0.20 to 6.16 μm, i.e., approximately 30 times. The highest growth rate of R _a is noted in the early pass of drawing. The increase in the dispersion of the value measured over drawing pass is also ascertained. The resulting phenomenon is explained by the effect of the copper grain turn.     

A mathematical model for the solution mining of primary copper ore: Part II. leaching by solution containing oxygen bubbles

The one-dimensional model developed previously to simulate thein situ leaching of copper from deeply-buried low-grade copper ore deposits is used to simulate thein situ operation in which the oxygen-saturated solution containing oxygen bubbles is introduced at the bottom of the chimney. The physical and chemical processes incorporated in the present model include the axial convective transport of mass and heat, axial dispersion of mass, mass transfer between the liquid and gas phases, fluid-solid mass transfer, diffusion of oxygen in the pores of ore fragments, and the dissolution of sulfide minerals. The coupled model equations are solved numerically by an implicit finite-difference method. Calculations have been made for various values of the volume fraction of oxygen bubbles (up to 0.1) in the fluid just downstream of the oxygen sparging nozzle. Calculated results indicate that, for a specific chimney considered, the total amount of copper extracted increases with increasing volume fraction of undissolved oxygen bubbles in the inlet fluid and increasing superficial velocity of the solution (up to 20 m per day). However, a further increase in the superficial velocity of liquid or undissolved oxygen bubbles does not enhance copper extraction. Calculated results also indicate that the total fractional recovery of copper increases with decreasing pyrite to chalcopyrite molar ratio, ore grade, particle size, and shape factor.     

Arsenic activities in molten copper and copper sulfide melts

In recent years, the concentration of the group Va elements such as arsenic, antimony, and bismuth has been increasing in copper concentrates. The elimination and recovery of these elements during the copper smelting process have presented serious problems. While the distribution of minor elements has been studied extensively, very little knowledge exists on the activities of these minor elements in copper mattes. Consequently, in this study the activities of arsenic were measured to determine activity coefficients of arsenic in the dilute solution region of molten copper, in Cu₂S saturated copper, and in copper mattes equilibrated with copper at 1423 K by a mass spectrometric Knudsen effusion technique. Formerly with the Department of Metallurgy and Materials Science, University of Toronto, Toronto, ON, Canada     

Coating of graphite fibers with tungsten carbide using solid and liquid copper as a transfer medium

An attempt was made to coat graphite fibers with tungsten carbide. Solid and liquid copper were used as a diffusion medium for tungsten to migrate to the surface of the graphite fibers at elevated temperature to form carbides. It was found that it is possible to electroplate Cu-1 pct W alloy on graphite fibers. It was established that this alloy contained tungsten in atomic dispersion. It was fur-ther discovered that tungsten was not in an equilibrium condition in copper and upon heat treatment formed fine precipitates instead of diffusing to the surface of the fiber to form tungsten carbide. However, it was also found that tungsten has a certain solubility in liquid copper and thus it was possible to obtain carbide coatings on graphite fibers by using liquid copper as a transfer agent for tungsten.     

Microstructure and strength of nanocrystalline copper alloy prepared by mechanical alloying

Polycrystalline materials having an ultrafine grain size may be prepared by mechanical alloying. Such a material has been prepared here with a copper matrix and a uniform dispersion of particles which stabilises the fine microstructure. It is shown that the grain size of the copper matrix may be explained in terms of the conventional models of boundary pinning by particles, even for grain sizes below 40 nm. For grain sizes larger than about 100 nm, material strength may be explained by dislocation-particle interactions as illustrated by TEM observations. For grain sizes below this limit, however, strengthening is not as great as dislocation theory would predict based on the distribution of particles in the material; in addition TEM observations show no indication of the presence of dislocations. A different deformation mechanism seems to control strengthening for these materials of nano-scale grain size.     

Direct electrolytic refining of end-of-life industrial copper waste scraps for production of high purity copper powder

The end-of-life electric cables from both domestic and industrial sources offer an attractive resource of copper metal. In addition, copper wastes generated during fabrication of copper components remains another valuable source of recyclable copper. This work reports a simple, cost-effective and eco-friendly direct electrolytic refining using waste electrical copper wire scrap and copper plate rejects for producing the value added high purity copper powder. Suitable anode support system was applied in which compressed wire scrap or copper plate rejects were held to make anode for electrolytic cell. Electrolysis parameters like current density, acid concentration and copper ion concentration were varied to arrive at optimum condition. Results showed the energy consumption of 1.44 kW h/kg at 89% current efficiency for producing the copper powder, that consisted of >80% of–325 mesh size particles, from waste copper wire anodes. However, slightly lower energy consumption of 1.32 kW h/kg at 91% current efficiency was observed during production of copper powder from copper fabrication rejects. The copper powder thus produced was characterised by chemical analysis, XRD and optical microscope to examine the purity and morphology etc. and found suitable for powder metallurgical applications. Present investigations have established the potential utilisation of copper waste wire scrap and copper plate rejects for the production of value added high purity copper powder.     

高铜载金炭铁盐法脱铜试验研究

某高铜载金炭中金品位2. 58 kg/t,铜品位50. 85 kg/t。针对该载金炭中铜品位高,影响吸附作业的问题,采用铁盐法进行脱铜试验研究,并考察脱铜液再生利用的影响因素。结果表明:采用铁盐法脱铜工艺处理高铜载金炭,在液炭比9∶1,脱铜时间6 h,脱铜温度25℃,氯化铁用量6 kg/t,硫酸用量15 kg/t的条件下,脱铜率可达97. 52%,且金基本不被浸出;脱铜液采用萃取-反萃工艺处理,可实现铜的综合回收,萃余液通过空气氧化后返回脱铜作业循环利用,脱铜率可达到97. 46%。     

Hydrogen reduction of spent copper electrolyte

The recovery of copper powder and the removal of arsenic from spent copper electrolyte by means of hydrogen reduction aimed at purifying the spent copper electrolyte were studied. About 90% of the copper in the electrolyte could be recovered in the form of pure copper powder after 20 min reduction at 180° at a hydrogen pressure of 20 kg cm^?2 (2.0 MPa). An induction period, due to slow hydrogen reduction of As⁵⁺ to As³⁺, could be eliminated as a result of the addition of copper powder as a reductant. Arsenic, antimony and bismuth in the liquor have been found to catalyze the hydrogen reduction of copper. When the copper concentration in the treated solution reached a certain low level, copper arsenide, Cu₃As₁ was formed on the surface of copper through hydrogen reduction of As³⁺ ions. This reaction was very slow and a long reaction time was required for complete removal of arsenic. Therefore, in order to purify spent copper electrolyte, some arsenic removal technique (e.g., solvent extraction) should be combined with hydrogen reduction.     

铜粉对MIM钨铜合金组织和性能的影响

采用金属注射成形（MIM）技术制备了钨铜合金,定量表征了铜粉的粉末粒度和粒形,重点研究了铜粉粒度和粒形对MIM钨铜合金组织与性能的影响。通过对比铜粉的粒径、粒度分布宽度、长宽比、粗糙度、赘生物指数和钝度等特征参数,破碎铜粉与水雾化铜粉颗粒呈枝晶状,粒径远小于还原铜粉,但破碎铜粉粒度分布宽,微观结构上的规则度、表面光滑程度以及分散程度最佳。破碎铜粉混合钨粉为原料,通过MIM技术制备钨铜注射生坯致密度高、缺陷少,烧结后钨铜合金的组织与性能最优,致密度为96.2%,硬度为235HV,抗弯强度为1 200 MPa,热导率为128 W/(m·K),电导率为30%IACS。     

Preparation of fine copper powders from organic media by reaction with hydrogen under pressure: Part II. The kinetics of particle nucleation,growth, and dispersion

The kinetics of very tine copper powder (1 to 2 μm) production by hydrogen reduction of solvent extracted copper chelates have been determined. The Avrami-Erafeer model for nucleation growth processes has been found to best describe the precipitation kinetics. The model parameters were correlated with reasonable success to the morphology of the copper powder. The chemically controlled particle formation process was found to exhibit 30 to 58 kJ/mol activation energy depending on the temperature range and a complex dependency (from first order to fractional/zero order) on hydrogen pressure. A steric stabilization model has been advanced to interpret the cooperative action of decanol and Versatic 10 in stabilizing the very fine copper powder dispersion.