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通过电化学研究 ,考察了氨溶液中砷黄铁矿的阳极氧化反应。实验表明氧化生成的表面膜对反应有抑制作用 ,该膜具有多孔性 ,可使反应继续进行。低温时 ,阳极氧化过程由电化学反应控制 ;高温时 ,反应受扩散过程控制。氨浓度对氧化过程的反应速率没有显著影响 ,溶液中Cu2 能降低氧化峰电位 ,改变氧化表面膜的形态 ,使膜的孔隙增大 ,反应速度加快。砷黄铁矿的阳极氧化总反应为FeAsS 11H2 O =Fe(OH) 3 SO2 -4 HAsO2 -4 18H 14e。 相似文献
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以铜氨废液为原料,水合肼为还原剂制备纳米铜粉。在水合肼浓度为3mol/L、pH值为10.0、温度为75℃的条件下,铜离子沉淀率可达98.66%。采用X射线衍射仪对铜粉进行了表征,并讨论了制备条件对纳米铜粉的影响。 相似文献
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利用扫描电镜、X射线衍射仪和氧化称重实验对铜表面氧化速率进行研究,分析了不同组织、晶粒和温度对铜氧化性能的影响。结果表明:铜的组织结构是影响其氧化性能的主要因素,非密排的(100)晶面上界面能高、晶面原子堆垛相对疏松和原子尺度上粗糙,且氧化膜生长连续,氧化速率高于密排的(111)晶面;温度升高,铜表面的内能增大,铜原子较易成为活化原子与氧气发生反应,同时增大了铜原子在氧化膜中的扩散速率,加速了铜的氧化;铜试样经过等径角挤压(ECAP)后,(111)晶面铜表面的面积增大,氧化速率降低,晶界不是影响铜氧化速率的主要因素,能量较小的晶面原子所占的面积增大,铜的氧化速率减小。 相似文献
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黄铜在铜氨液中应力腐蚀破裂的临界电位及缝内状态的研究 总被引:2,自引:0,他引:2
一、前言确定应力腐蚀临界破裂电位对于研究应力腐蚀的机理及进行电化学保护具有重要意义。目前主要有几种测定方法,如控制电位应力腐蚀破裂试验法、动电位扫描法、模拟闭塞电池法、电化学计算法及电流衰减法等,以控制电位的应力腐蚀试验法最为准确可靠。本实验采用控制电位固定载荷法,对浸泡在铜氨稀溶液中的黄铜试件进行恒电位拉伸,从而确定其破裂临界电位。 相似文献
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采用平行比较法研究了Pt-10Rh、Pt-4Pd-3.5Rh和Pt-12Pd-3.5Rh-RE合金以及其氨氧化催化剂的结构与性能.与传统的Pt-10Rh和Pt-4Pd-3.5Rh合金及其催化剂比较,以稀土改性的合金,即Pt-12Pd-3.5Rh-RE合金及其催化剂,具有更高的力学性能(包括室温和高温拉伸强度、持久强度和... 相似文献
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含铜金矿的压力氧化浸出及其机理 总被引:4,自引:1,他引:4
含铜金矿在氧气分压为o.45 MPa、温度约为110℃条件下于高压釜中氧化一定时间,浸出铜后,渣氰化浸金,获得的铜、金浸出率分别为90.3%和96.55%.通过分析X射线衍射谱及CuFeS2-H2SO4-NaCl-H2O体系在25℃下的ψ-pH图,确定了载金矿物的氧化机理,分析了浸出体系的酸度、温度及氯化钠浓度对含铜金矿预氧化及浸出过程的影响规律.结果表明:硫化矿的氧化溶解首先是磁黄铁矿,其次是铜的次生硫化矿,再次是黄铜矿,最后是黄铁矿;载金黄铜矿的氧化首先是铁从黄铜矿的晶格中氧化溶解出来,生成中间产物CuS2和CuS;较高的酸度和氯化钠浓度有利于单质硫的生成、三价铁的水解和铜的浸出,进而有利于金浸出率的提高. 相似文献
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《中国有色金属学会会刊》2010,(10)
Extraction of copper and ammonia from Cu2+-NH3-Cl--H2O solution using laboratorialy synthesized sterically hindered β-diketone(4,4-dimethyl-1-(4-dodecylphenyl)-1,3-pentanedione) was studied.The effects of the copper concentration,the total ammonia concentration,the initial pH in the aqueous phase,the phase ratio,and the temperature on copper extraction ratio and ammonia extraction in loaded organic phase were investigated using this sterically hindered β-diketone.Under the conditions of temperature 25℃,contact time of two phases 30 min,phase ratio 1-1,concentration of copper 3 g/L,concentration of total ammonia 3 mol/L,aqueous pH 8.43,and the concentration of β-diketone in organic phase 20%(volume fraction),ammonia in aqueous phase is much lower to be extracted by organic phase(just 14.5 mg/L),while the extraction rate of copper is 95.09%. 相似文献
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Studies of the stress corrosion cracking (SCC) of 99.999% copper and Cu-Zn alloys containing up to 10 wt%Zn in NH4OH solution were made with varying concentrations (0.03–0.07 M) and temperatures (40–70°C). Stress corrosion cracking occurs on pure copper and all of the alloys under the condition in which thick tarnish film (Cu2O oxide film) forms. The path of cracking is transgranular for pure copper and alloys containing < 1.3 wt%Zn, but intergranular for alloys containing > 1.3 wt%Zn. Crack propagation rates and times-to-failure estimated by the tarnish rupture theory, utilizing experimentally determined values of the fracture strain of film and the creep rate of specimens during SCC tests, are in good agreement with those observed under constant load. 相似文献
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Ammonia leaching kinetics of a complex Cu-ore assaying 8.8% Cu and 36.1% Fe was examined. Mineralogical characterization indicated that the major phase of the ore was siderite with chalcopyrite as the major sulfide mineral. The effects of parameters such as agitation, temperature, NH3 concentration, particle size and oxygen partial pressure (pO2) were investigated. Under the standard leaching conditions of 125–212 µm particle size, 120 °C, 1.29 mol/L NH3 and 202 kPa of pO2, about 83% Cu could be selectively extracted in 2.5 h. However, when using higher NH3 concentration and lower particle size, more than 95% extraction was achieved. The leaching process was found to be surface reaction controlling. The estimated activation energy was (37.6±1.9) kJ/mol and empirical orders of reaction with respect to pO2 and [NH3] were about 0.2 and 1, respectively. 相似文献
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采用高位阻β-二酮(1-(4’十二烷基)苯基-3-叔丁基-1,3-丙二酮)作为萃取剂从模拟印刷电路板(PCBs)蚀刻废液中萃取铜。利用离子强度与萃取反应平衡常数的关系校正模拟的萃取等温线,该模拟萃取等温线与实验测得萃取等温线基本相符。通过实验确定萃取剂浓度、相比、萃取级数和反萃级数等萃取工艺参数。结果表明,在室温下对于铜离子浓度为112g/L、总氨浓度为7mol/L的模拟氨性蚀刻废液的最佳萃取条件为:萃取剂浓度为40%,相比为5:4,萃取时间为5min。在此条件下,经过一级萃取,蚀刻废液中铜离子浓度可降低至63.24g/L,能返回到电路板的生产中循环使用。用含铜30g/L,硫酸浓度180g/L的模拟废电解液对负载有机相进行反萃,相比(O/A)为1:2,经一级反萃,铜的反萃率可达98.27%。 相似文献
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《稀有金属(英文版)》2015,(6)
Finite element analyses including a cohesive zone model(CZM) were conducted to investigate the role of corrosion product films(CPFs) in stress corrosion cracking(SCC) for copper in an ammoniacal solution. It is found that a tensile CPF-induced stress generates near the interface between the CPF and the copper substrate at the substrate side in front of the notch tip for a U-shaped edgenotched specimens. The CPF-induced stress is superimposed on the applied stress to enhance emission and motion of dislocations. The peak opening stress(S_(11)) increases with an increase in CPF thickness and a decrease in CPF Young's modulus. Damage mechanics based on the CZM was applied to study the stress corrosion crack initiation and propagation by analyzing the stress redistributions and load–displacement curves. The results show that the crack initiates first in the CPF and then propagates to the copper substrate. The fracture strain of the specimen covered a CPF is lower than that without a CPF. Based on the simulation results, the mechanism of the CPF-induced SCC, which promoted the initiation and propagation of the stress corrosion cracks, was discussed. 相似文献
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Oxidation of copper and electronic transport in thermally-grown large-grain polycrystals of nonstoichiometric copper oxides were studied at elevated temperatures. Thermogravimetric copper oxidation was studied in air and oxygen at temperatures between 350 and 1000°C. From the temperature dependence of the oxidation rates, three different processes can be identified for the oxidation of copper: bulk diffusion, grain-boundary diffusion, and surface control with whisker growth; these occur at high, intermediate, and low temperatures, respectively. Electrical-conductivity measurements as a function of temperature (350–1134°C) and oxygen partial pressure (10–8–1.0 atm) indicate intrinsic electronic conduction in CuO over the entire range of conditions. Electronic behavior of nonstoichiometric Cu2O indicates that the charge defects are doubly-ionized oxygen interstitials and holes. The calculated enthalpy of formation of oxygen (
) and hole-conduction energy (EH) at constant composition for nonstoichiometric Cu2O are 2.0±0.2 eV and 0.82±0.02 eV, respectively.This work was supported by the U.S. Department of Energy, under Contract W-31-109-Eng-38. 相似文献
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《Metallography》1981,14(4):335-345
Morphological features of the lime-enhanced hydrogen reduction of cuprous sulfide pellets were investigated as a function of temperature and time by scanning electron microscopy. Moderate temperatures of reduction (600–750°C) were found to result in the formation of fibers and loops of copper, whereas at high temperatures of reduction (900–1000°C) only sintered crusts of spongy copper were obtained. The sequence of nucleation and growth of copper fibers was found to be the formation of pits and pores on the sulfide particles, followed by the nucleation of copper preferentially in these pores, the emergence of copper hairs from the sulfide base, and the formation and thickening of loopy fibers. These events are explained on the basis of the reduction characteristics and nonstoichiometry of cuprous sulfide and its mismatch with the product metal. While lime enhances the bulk reduction rate of cuprous sulfide, it does not seem to affect the mechanism of copper fiber formation. 相似文献
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The kinetics and mechanism of copper oxidation have been measured over the temperature range 900–1050°C and the pressure range 5×10?3 to 8×10?1 atm. It has been shown that, at the pressures lower than the dissociation pressure of CuO, the oxide scale formed on flat fragments of the copper specimens is compact and composed of a single layer, adhering closely to the metallic base. Growth of the scale proceeds under these conditions by outward diffusion of metal. The rate of the process under the conditions for which single-phase scales are formed increases with increasing oxygen pressure according to the equation: $${\text{k''}}_{\text{p}}^{} = const {\text{p}}_{{\text{O}}_{\text{2}} }^{{\text{1/3}}{\text{.9}}} $$ . the activation energy for oxidation is 24 ± 2 kcal/mole. On the basis of theFueki-Wagner method and the method proposed in the present work, the self-diffusioncoefficients of copper in cuprous oxide were calculated as a functionof oxygen pressure and temperature. It has been shown that distribution of thedefect concentration in the growing layer of the scale is linear. 相似文献
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在1873 K条件下对铜在富FeO熔渣中的氧化溶解行为进行了研究.结果表明:铜氧化物在富FeO熔渣中以Cu2O的形式存在;熔渣中CaO的含量将对铜的氧化溶解产生影响,随着渣中CaO含量的增加,熔渣中的铜含量逐渐下降,但在不同温度下,这种影响的作用各不相同;当温度较高时,渣中CaO含量对铜的氧化溶解影响较大,且随着温度的降低,其影响作用明显变缓;反应体系的氧分压对铜的氧化溶解影响较大,在熔渣中γ(CuO0.5)不变的情况下,铜氧化物的溶解与体系氧分压的四分之一次方之间呈正线性关系. 相似文献