Thermodynamics of copper matte converting: Part III. Steady-state volatilization of Au,Ag, Pb,Zn, Ni,Se, Te,Bi, Sb,and As from slag,matte, and metallic copper

A comprehensive compilation of various thermodynamic data required for a complete analysis of copper matte converting reactions is presented. The data comprise estimated free energies of formation for such gases as SeO, SeS, TeO, TeS, BiO, BiS, SbO, SbS, AsO, and AsS, as well as activity coefficients in dilute copper alloys and vapor pressures of various elements and compounds. The volatilization of minor elements in steady-state reactors comprising gas and several condensed phases is mathematically formulated, and a parameter which governs the volatilization in such reactors is defined and named volatilization constant. The vapor pressures of various volatile species are calculated thermodynamically for the Noranda Process reactor by assuming equilibrium conditions. The volatilization constants of various minor elements are expressed explicitly as functions of oxygen and sulfur activities. Formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT     

Volatilization of bismuth in copper matte converting — computer simulation

A computer model has been developed to simulate the behavior of bismuth in copper matte converting at 1100 to 1300 ‡C. The rate equation is integrated numerically by dividing a continuous process of matte converting into a great number of microsteps, in each of which the volatilization of Bi-bearing gases is thermodynamically calculated by assuming a steady state. The bubbles of offgas consisting of SO₂ and N₂ are assumed to be saturated with the vapors of BiS, Bi, BiO, and Bi₂. However, the partial pressures of BiO and Bi₂ are found to remain negligible at all stages of converting. BiS is the most volatile species over the slag-making stage with low grade mattes, but its volatility decreases markedly, becoming negligibly low over white metal. When the copper content of the initial matte is known together with the weight of matte, converting temperature and blowing rate of tuyere air, the present computer model can predict the Bi contents in all the phases involved (gas, slag, matte, copper) at any given time. The predictions by the present computer model are compared with the known commercial data from various smelters around the world. The agreements between the computer predictions and the commercial data are excellent in all cases, so that the present computer model can be used to monitor and optimize the bismuth elimination in the actual industrial operations of copper matte converting. Formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112     

Activities of CoS and FeS in copper mattes and the behavior of cobalt in copper smelting

The distributions of cobalt and iron between metallic copper and high copper mattes were measured at 1400 and 1500 K. A value of 0.40 ±0.02 was found as the Raoultian activity coefficient of CoS at infinite dilution in the Cu₂S-FeS-CoS mattes. The present activities of FeS in the Cu-saturated Cu₂S-FeS mattes were found to deviate more positively than those reported by Krivsky and Schuhmann at 1623 K, and the positive deviation from the Temkin's ideality was greater at 1400 K than at 1500 K. Using the activity coefficient of CoS, the partitions of cobalt between copper mattes and fayalitic slags were calculated for various conditions of copper smelting. It was found that cobalt exhibits, in the matte-slag equilibria, chemical properties intermediate between nickel and iron, but much closer to iron than to nickel. The overall recovery of cobalt in blister copper depends on matte grade, and is as low as 3 pct at best. When a high cobalt recovery is desired, therefore, a copper concentrate rich in cobalt must not be processed by conventional pyrometallurgical technology in view of the inevitably high loss to slag. Formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, Utah     

The impact of electrical current, mechanical bending, and thermal annealing on tin whisker growth

This paper presents the results of an eight-month design-of-experiment assessment of whisker growth on bright and matte tin-plated copper, mechanically deformed and unformed coupons, subject to a continuous 50 °C/50%RH environment, with and without the presence of a constant electrical current density magnitude of 0.48 × 10² A/cm². Whiskers were observed to grow both at the anode and cathode end. The distribution-based data showed a reduction in whisker density due to annealing and/or the application of electrical current for both bright and matte tin. However, the application of electrical current was observed to increase the standard deviation of the length distribution, and to generate longer whiskers.     

活性氧化铜粉的工艺条件研究

研究开发了一条由纯铜片制备电镀级活性氧化铜粉的工艺方法。以铜片为原料,经过碳酸氢铵和氨水溶铜,常压脱氨,焙烧三阶段得到活性氧化铜粉。用SEM、ICP等方法对所得的活性氧化铜粉的性能进行了表征,结果表明,采用该法得到的活性氧化铜粉纯度达到99%以上,金属杂质含量和溶解速度完全符合电镀级氧化铜粉的要求,可以直接用到线路板的电镀工序。     

Continuous Synthesis of Device‐Grade Semiconducting Polymers in Droplet‐Based Microreactors

A method is reported for the controlled synthesis of device‐grade semiconducting polymers, utilizing a droplet‐based microfluidic reactor. Using poly(3‐hexylthiophene) (P3HT) as a test material, the reactor is shown to provide a controlled and stable environment for polymer synthesis, enabling control of molecular weight via tuning of flow conditions, reagent composition or temperature. Molecular weights of up to 92 000 Da are readily attainable, without leakage or reactor fouling. The method avoids the usual deterioration in materials quality that occurs when conventional batch syntheses are scaled from the sub‐gram level to higher quantities, with a prototype five‐channel reactor producing material of consistent molecular weight distribution and high regioregularity (>98%) at a rate of ≈60 g/day. The droplet‐synthesized P3HT compares favorably with commercial material in terms of absorption spectrum, polydispersity, regioregularity, and crystallinity, yielding power conversion efficiencies of up to 4% in bulk heterojunction solar cells with [6,6]‐phenyl‐C61‐butyric acid methyl ester.     

Synthesis,Structure, Properties,and Applications of Bimetallic Nanoparticles of Noble Metals

Bimetallic nanoparticles of noble metals are of high interest in imaging, biomedical devices, including nanomedicine, and heterogeneous catalysis. Synthesis, properties, characterization, biological properties, and practical applicability of nanoparticles on the basis of platinum group metals and the coin metals Ag and Au are discussed, also in comparison with the corresponding monometallic nanoparticles. In addition to the parameters that are required to characterize monometallic nanoparticles (mainly size, size distribution, shape, crystallographic nature, surface functionalization, charge), further information is required for a full characterization of bimetallic nanoparticles. This concerns the overall elemental composition of a bimetallic nanoparticle population (ratio of the two metals) and the internal distribution of the elements in individual nanoparticles (e.g., the presence of homogeneous alloys, core–shell systems, and possible intermediate stages). It is also important to ensure that all particles are identical in terms of elemental composition, that is, that the homogeneity of the particle population is given. Macroscopic properties like light absorption, antibacterial effects, and catalytic activity depend on these properties. The currently available methods for a full characterization of bimetallic nanoparticles are discussed, and future developments in this field are outlined.     

激光切割1Cr18Ni9Ti不锈钢管材挂渣和飞渣的研究

研究了激光无氧切割不锈钢管材所形成挂渣的组织、成分和飞渣的形态。结果表明挂渣依托于基材,其组织为不同生长方向而交错形成的枝晶组织,且成分不同;挂渣的原因在于材料含有大量高表面张力的合金元素;飞行距离不同导致飞渣形貌由相互连接的薄饼状逐渐过渡到单个的类似球状的颗粒。     

Influence of External Strain on the Growth of Interfacial Intermetallic Compounds Between Sn and Cu Substrates

This study used a four-point bending procedure to investigate the influence of compressive and tensile strain on the growth of an interfacial Cu-Sn intermetallic compound (IMC) layer. The test specimens were prepared by depositing 25?μm layers of matte or bright tin atop a copper substrate using electroplating. Samples were then placed in a furnace at 200°C, and external bending strain was applied through a strained substrate. Comparisons were made between samples undergoing tensile strain or compressive strain, and those without strain. We observed the influence of strain levels and aging time on the formation of the IMC. Both tensile and compressive strain influenced the formation of the Cu/Sn IMC. In matte tin samples, the IMC thickness increased under compressive strain and decreased under tensile strain. In contrast, in bright tin samples, the IMC thickness increased under both compressive and tensile strained substrate conditions. The growth rate of IMC was faster in strained bright tin samples than in strained matte tin samples. Moreover, the formation of IMC microscopic structures under external strain differed considerably according to the source of tin.     

Unsupervised and reliable image matting based on modified spectral matting

Spectral matting is the state-of-the-art image matting and also a milestone in theoretic matting research. For spectral matting without user intervention, the accuracy of alpha matte is low and the computational cost is high. Therefore, this paper presents a modified version of spectral matting to greatly increase the accuracy of alpha matte and effectively reduce the computational cost. In the proposed modified spectral matting, palette-based component classification is used to obtain reliable foreground and background components. Next, the corresponding matting components are obtained via a linear transformation of the smallest eigenvectors of the matting Laplacian matrix. Finally, the matting components of the foreground and the unknown regions are combined to from the complete alpha matte based on minimizing the matte cost. Moreover, image composition with consistency of color temperature is used to obtain the realistic image composition. Experimental results show that the proposed method outperforms the state-of-the-art methods based on spectral matting.     

云阳丝栗包遗址出土汉代青铜耳杯锈蚀的扫描电镜分析

利用扫描电子显微镜、激光共聚焦拉曼光谱仪和三维视频显微镜对云阳丝栗包遗址出土两件汉代青铜耳杯的锈蚀进行观察和分析,结果表明:青铜耳杯锈蚀层主要含铅、铜、磷和氯等元素且锈蚀层存在铅、磷富集现象;铅、磷和氯以磷氯铅矿的形式存在;磷氯铅矿的形成过程应为氯元素和磷元素从外部环境向青铜基体扩散,在微生物的作用下,与基体内的铅反应生成磷氯铅矿(Pb5(PO4)3Cl).     

Structure of the Cu<Subscript>2</Subscript>Se compound produced by different methods

Copper-selenide (Cu₂Se) samples are produced by mechanochemical synthesis and compaction by spark plasma sintering and hot pressing. The structure and phase composition of the samples before and after heat treatment are studied by the X-ray diffraction technique and electron microscopy. The character of changes in the shape and size of structural elements of the samples is shown. Variations in the phase composition of copper selenide in the temperature range from 25 to 500°C are studied in situ.     

CoWBP capping barrier layer for sub 90 nm Cu interconnects

Electroless cobalt films have been obtained by deposition using a plating bath containing two reducing agents: dimethylamineborane (DMAB) and sodium hypophosphite. This formulation allows spontaneous activation on copper followed by auto catalytic electroless plating. CoWBP and CoBP films are proposed as diffusion barriers and encapsulation layers, for copper lines and via contacts for ULSI interconnect applications. The crystalline structure, chemical composition and oxidation states of the elements were studied, as well as the electrical resistivity, topography and morphology of the films. The film composition was characterized as a function of the solution composition; the barrier properties of the films were tested and an oxidation resistance study was conducted. The films were characterized and the results show that they can be applied as capping layers for ULSI copper metallization.     

Role of intrinsic stresses in the phenomena of tin whiskers in electrical connectors

The connector industry is at a crossroads with respect to selecting lead-free coatings in response to legislation and customer demands. Component manufacturers have long used tin-lead coatings because of lead's ability to inhibit tin whisker formation. Several lead-free alternate finishes such as pure tin, tin-bismuth, tin-copper, tin-zinc, Pd, and Pd-Ni-Au have been proposed. One simple, economical, and easy drop-in replacement is pure matte tin. Unfortunately, pure tin films have a fairly high risk of whisker formation. Factors, such as substrate material, plating process variables, and assembly operations also play a role in whisker generation. The stresses imposed at each process step pose a serious threat to whiskering. We have critically evaluated three matte tin chemistries by changing bath composition and deposition parameters. We also characterized stresses in these matte tin coatings by using flexure beam and X-ray diffraction techniques. This paper identifies stress types encountered in various connector applications, provides an insight to the users about practical situations, and suggests whisker mitigation strategies. The impact of environmental (e.g., temperature and humidity) stresses on tin coatings is also discussed.     

The peak sidelobe of the phased array having randomly located elements

A formula is derived for the peak sidelobe level of a phased array in which the elements are randomly located. The parameters of the formula are the number and size of the array elements, size of the array, wavelength, beamsteering angle, and signal bandwidth. The theory is tested by measurement of the peak sidelobe of several hundred computer-simulated random arrays. Unlike the case for the conventional array the effect of spatial taper (nonuniform density of element location) upon the peak sidelobe level is minor. The peak sidelobe of the two-dimensional planar array is approximately 3 dB higher than that of the linear array of the same length and same number of elements.     

Modeling the distribution of DCT coefficients for JPEG reconstruction

In the paper, the one moment (OM) method for the estimation of the shape parameter of generalized Gaussian distribution (GGD) is derived from the two moments method in the case when the moments converge in the limits to the same value. The one moment method reduces to the maximum likelihood (ML) method in the special case when the moment equals the shape parameter. The proposed method exhibits smaller complexity of calculations over ML keeping the same error.Assuming Laplacian distribution, there exists a method for optimally biasing the reconstruction levels for the quantized AC discrete cosine transform (DCT) coefficients using only the quantized ones available at the JPEG decoder [J.R. Price, M. Rabbani, Biased reconstruction for JPEG decoding, IEEE Signal Process. Lett. 6 (12) (1999) 297–299; R. Krupiński, J. Purczyński, First absolute moment and variance estimators used in JPEG reconstruction, IEEE Signal Process. Lett. 11 (8) (2004) 674–677].Many researchers stated that the subset of images can be modeled with GGD with the shape parameter lower than 1. By assuming a source signal with GGD with the exponent 0.5, equations in a closed form for the centroid reconstruction can be obtained as it cannot be done for a GGD model. The ML method of discrete GGD 0.5 is derived, which requires the estimation of only one parameter. For selected images, the values of PSNR coefficients are compared for both distributions.     

Investigation of Sn Whisker Growth in Electroplated Sn and Sn-Ag as a Function of Plating Variables and Storage Conditions

Sn whiskers are becoming a serious reliability issue in Pb-free electronic packaging applications. Among the numerous Sn whisker mitigation strategies, minor alloying additions to Sn have been proven effective. In this study, several commercial Sn and Sn-Ag baths of low-whisker formulations are evaluated to develop optimum mitigation strategies for electroplated Sn and Sn-Ag. The effects of plating variables and storage conditions, including plating thickness and current density, on Sn whisker growth are investigated for matte Sn, matte Sn-Ag, and bright Sn-Ag electroplated on a Si substrate. Two different storage conditions are applied: an ambient condition (30°C, dry air) and a high-temperature/high-humidity condition (55°C, 85% relative humidity). Scanning electron microscopy is employed to record the Sn whisker growth history of each sample up to 4000 h. Transmission electron microscopy, x-ray diffraction, and focused ion beam techniques are used to understand the microstructure, the formation of intermetallic compounds (IMCs), oxidation, the Sn whisker growth mechanism, and other features. In this study, it is found that whiskers are observed only under ambient conditions for both thin and thick samples regardless of the current density variations for matte Sn. However, whiskers are not observed on Sn-Ag-plated surfaces due to the equiaxed grains and fine Ag₃Sn IMCs located at grain boundaries. In addition, Sn whiskers can be suppressed under the high-temperature/high-humidity conditions due to the random growth of IMCs and the formation of thick oxide layers.     

Effect of temperature on copper indium selenization

The reaction kinetics of copper indium diselenide formation is studied by measuring species composition as a function of time at 250°C and 325°C in a tubular chemical vapor deposition reactor. This extends our previous modeling and experimental study at 400°C. The initial copper–indium alloy is analyzed at the reaction temperatures using high-temperature X-ray diffraction measurements. This modifies the understanding of the chemistry of the copper indium growth kinetics and a new set of model equations is presented. The specific reaction rate constants and activation energies for the chemical reactions are obtained, enabling one to calculate the holding time for the reaction. © 1997 John Wiley & Sons, Ltd.     

Determination of cut-off wavelength and composition distribution in Hg1-xCdxTe

The determination of cut-off wavelength, λ _co, and composition distribution for Hg_1-xCd_xTe has been discussed in this paper. A shift of the cut-off wavelength was found from the photo-response calculation for the HgCdTe devices with the same energy gap E_g but different thickness d. An expression of λ _co(x,T,d) has been derived from the half-maximum photo-response curve calculation. The composition uniformity has been determined from the room-temperature transmission fitting procedure. The composition real space distribution is suggested to be determined by the combination of absorption edge phenomenon and thermal imaging technique.     

Surface Chemistry Dictates the Osteogenic and Antimicrobial Properties of Palladium-, Platinum-, and Titanium-Based Bulk Metallic Glasses

Titanium alloys are commonly used as biomaterials in musculoskeletal applications, but their long-term efficacy can be limited by wear and corrosion, stress shielding, and bacterial colonization. As a promising alternative, bulk metallic glasses (BMGs) offer superior strength and corrosion resistance, but the influence of their chemical composition on their bioactivity remains largely unexplored. This study, therefore, aims to examine how the surface chemistry of palladium (Pd)-, platinum (Pt)-, and titanium (Ti)-based BMGs can steer their response to biological systems. The chemical composition of BMGs governs their thermophysical and mechanical properties, with Pd-based BMGs showing exceptional glass-forming ability suitable for larger implants, and all BMGs exhibiting a significantly lower Young's modulus than Ti-6Al-4 V (Ti64), suggesting a potential to reduce stress shielding. Although BMGs feature copper depletion at the near surface, their surface chemistry remains more stable than that of Ti64 and supports blood biocompatibility. Fibrin network formation is heavily dependent on BMGs’ chemical composition and Ti-based BMGs support thicker fibrin network formation than Ti64. Furthermore, BMGs outperform Ti64 in promoting mineralization of human bone progenitor cells and demonstrate antimicrobial properties against Staphylococcus aureus in a surface chemistry-dependent manner, thereby indicating their great potential as biomaterials for musculoskeletal applications.