The electroremoval of copper from dilute waste solutions using Swiss-roll electrode cell

Copper is usually present in concentrations less than 5 g/L⁻¹ in dilute waste solutions. The low concentrations make these solutions unsuitable for the electro-flow owinning processes via conventional electrolysis cells. Unconventional, two-and three-dimensional electrode cells with relatively large cathodic area are essential for such treatment. Different types of cells are mentioned in the literature. Among these cells, the two-dimensional Swiss-roll cell (SR) is considered in this study. The effects of cathodic current densities, initial copper concentrations, free sulfuric acid concentration, the presence of iron and zinc cations, and the rate of flow of the solution on both the cathodic current efficiency and power consumption were studied. Copper was removed from synthetic and industrial mixtures of Cu/Fe/Zn sulfate solutions to less than 5 ppm with power consumptions of 10.326 kWh/kg⁻¹ and 8.61 kWh/kg⁻¹, respectively. The correlation between the SR cell and packed-column cell on such treatment was also considered.     

Quantifying Thermal Spray Coating Architecture by Stereological Protocols: Part I. A Historical Perspective

This article presents, from a historical perspective, some stereological protocols of the first order. Such protocols can be implemented to quantify statistically the architecture of thermal spray coatings and their relevant features (pores, lamellas, etc.). A forthcoming Part II of this article will address some key points to implement, from a practical point of view, such protocols.

Influence of domestic sewage leakage on the collapse of tropical soils

In the studied region, 35% of the soil collapses are related to leakage from sewage ducts. The paper describes the soils from this part of Brazil and a series of laboratory tests undertaken using water and domestic sewage fluid as the wetting agents. It is considered that the presence of soaps and detergents as recorded by the sodium concentration facilitates the densification of the soils and hence has a major effect on the surface settlement/collapse.      

Urban spatial pattern as self-organizing system: An empirical evaluation of firm location decisions in Cleveland–Akron PMSA,Ohio

Economic models of urban spatial patterns have largely ignored complexity as an attribute of urban systems. Complexity theorists on the other hand have not made sufficiently serious and sustained attempts to verify empirically the relevance of complex systems models for urban spatial patterns. This research bridges this gap by simulating the evolution of an urban employment pattern as a self-organizing complex system and seeking its empirical validation. It estimates the model’s parameters by using firm data aggregated to the level of municipalities in Cleveland-Akron Consolidated Metropolitan Statistical Area in Ohio. The interaction among four parameters, forces of attraction and dispersion and their respective rates of dissipation with distance, are modeled as a two-dimensional complex system. The research compares the states of the modeled system with empirical data to present viable methods for verification, calibration and validation of such models.

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Microstructure and properties of TiB/Ti-6Al-4V coatings produced with laser treatments

TiB/Ti-6Al-4V metal-matrix composite (MMC) layers were produced on Ti-6Al-4V substrates by laser cladding. A TiB₂/Ti powder mixture was used as a precursor to obtain a dispersion of TiB needles in the Ti alloy matrix, with the aid of an exothermic reaction between TiB₂ and Ti. A eutectic microstructure was obtained that consisted of an extremely homogeneous dispersion of TiB eutectic needles in the Ti alloy matrix, having a volume fraction as high as 0.33. Also, an equilibrium-like microstructure was found, consisting of a dispersion of both primary and eutectic TiB needles inside the Ti alloy matrix. An analysis of the geometry of the layers was performed and proved successful in determining the percentage of B. Further, it correctly predicted the variation of atomic B content as a function of laser power. The relative wear resistance coefficient, defined as the wear coefficient of the uncoated matrix divided by that of coating, shows an improvement by a factor as high as 1500 for the eutectic microstructure. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appeared on pp. 411–18 of the Proceedings.     

Tantalum oxide coatings as candidate environmental barriers

Tantalum (Ta) oxide, due to its high-temperature capabilities and thermal expansion coefficient similar to silicon nitride, is a promising candidate for environmental barriers for silicon (Si) nitride-based ceramics. This paper focuses on the development of plasma-sprayed Ta oxide as an environmental barrier coating for silicon nitride. Using a D-optimal design of experiments, plasma-spray processing variables were optimized to maximize coating density. The effect of processing variables on coating thickness was also determined. X-ray diffraction (XRD) was use to ascertain that the as-sprayed coatings were comprised of α- and β-Ta₂O₅, but were fully converted to β-Ta₂O₅ after a 1200 °C heat treatment. Grain growth of the Ta₂O₅ followed a time dependence of t ^0.2 at 1200 °C.     

The government <Emphasis Type="Italic">is</Emphasis> here to help: a small business perspective

Public-private partnerships between government and industry have been increasingly used as a vehicle for defining and executing R&D activities. Stimulus of smaller technology enterprises in particular is important, and this article explores this topic from the policy level as well as from organizations “on the ground.” The story in brief: challenges and opportunities. Editor’s Note: A hypertext-enhanced version of this article is available on-line at www.tms.org/pubs/journals/JOM/0412/Hunt-0412.html Warren H. Hunt, Jr. is technical consultant at TMS.     

The China factor: Aluminum industry impact

The emergence of China as a global economic force has influenced the technical enterprise generally and a number of industries specifically. The aluminum industry is an example, with effects on consumption and demand as well as production and supply. This article reviews these areas from both a historical and future perspective. For more information, contact W.H. Hunt, Jr., TMS, 184 Thorn Hill Road, Warrendale, PA 15086; (724) 776-9000, ext. 226; (724) 776-3770; e-mail whunt@tms.org.     

Effects of different metallurgical processing on microstructures and mechanical properties of inconel alloy 783

Different metallurgical processing, including the standard heat treatment, heat treatment without β aging, addition of high amount of Cr, and long-term isothermal exposure, was conducted on superalloy Inconel 783. For these processed materials, the tensile property and hardness at room temperature and stress relaxation behavior at 650 °C were examined. The testing results showed that isothermal exposure and heat treatment without β aging slightly enhanced the yield strength of alloy 783 at room temperature as well as all metallurgical processing in this study produced an identical stress relaxation behavior at 650 °C. The microstructure variation with different processing was analyzed using optical microscope, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).