International Journal of Minerals, Metallurgy and Materials

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Oxidation behavior of artificial magnetite pellets

2017, 24(6): 603-610. doi: 10.1007/s12613-017-1442-1

中文摘要(474) PDF(18) SpringerLink

摘要:
The oxidation behavior of artificial magnetite pellets was investigated through measurements of the oxidation degree and mineralogical analysis. The results show that artificial magnetite pellets are much easier to oxidize than natural magnetite. The oxidation is controlled through two different reaction mechanisms. The oxidation of artificial magnetite is dominated by internal diffusion, with an activation energy of 8.40 kJ/mol, at temperatures less than 800℃, whereas it is controlled by chemical reaction, with a reaction activation energy of 67.79 kJ/mol, at temperatures greater than 800℃. In addition, factors such as the oxygen volume fraction and the pellet diameter strongly influence the oxidation of artificial magnetite:a larger oxygen volume fraction and a smaller pellet diameter result in a much faster oxidation process.

研究论文

Kinetic modeling of copper bioleaching from low-grade ore from the Shahrbabak Copper Complex

Saman Beikzadeh Noei, Saeed Sheibani, Fereshteh Rashchi, Seyed Mohammad Javad Mirazimi

2017, 24(6): 611-620. doi: 10.1007/s12613-017-1443-0

中文摘要(536) PDF(14) SpringerLink

摘要:
The copper recovery from low-grade copper sulfide ore was investigated using microbial leaching. Several parameters substantially affect the bioleaching of copper; among them, pulp density and nutrient media were selected for investigation. The optimum conditions for copper recovery were a pulp density of 5 g/mL, a mixed-mineral salt medium of Acidithiobacillus thiooxidans (70vol%) and Acidithiobacillus ferrooxidans (30vol%), and 10vol% of inoculum. Under these conditions, the maximum bioleaching capacity of the medium for copper recovery was determined to be approximately 99%. The effect of pulp density on the kinetics of the bioleaching process was surveyed using both da Silva's method and constrained multilinear regression analysis. The kinetics of copper dissolution followed the shrinking core model, and the process was diffusion controlled at a pulp density of 5 g/mL. Nevertheless, at higher pulp densities, the process was controlled by chemical reaction.

研究论文

Recovery of copper from copper slag using a microbial fuel cell and characterization of its electrogenesis

Wei-ping Liu, Xia-fei Yin

2017, 24(6): 621-626. doi: 10.1007/s12613-017-1444-z

中文摘要(511) PDF(21) SpringerLink

摘要:
The microbial fuel cell, which can convert the chemical energy of organic matter into electricity via the catalytic action of microorganisms, is a novel environmentally friendly technology for wastewater treatment and energy generation. The electrical energy generated by the microbial fuel cell can be used as an alternative to a traditional external power source required to extract copper via electrolytic treatment. A dual-chamber microbial fuel cell (DMFC) for the treatment of copper slag sulfuric acid leach liquor was constructed. The electrogenesis performance of the DMFC and its ability to extract copper from the copper slag leachate were investigated. The results demonstrated that the maximum voltage was 540 mV when the DMFC achieved steady-state operation. The removal rate of copper ions was greater than 80.0%, and the maximum value was 92.1%. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the cathodal products. The results showed that the product deposited onto the cathode was copper and that its morphology was similar to that of the electrolytic copper powder. The DMFC can generate electricity and recover copper from copper slag simultaneously.

研究论文

Study on the separation process of non-metallic inclusions at the steel-slag interface using water modeling

Ye-lian Zhou, Zhi-yin Deng, Miao-yong Zhu

2017, 24(6): 627-637. doi: 10.1007/s12613-017-1445-y

中文摘要(550) PDF(27) SpringerLink

摘要:
The separation process of non-metallic inclusions at the steel-slag interface was simulated by physical modeling. Three different kinds of particles (octahedral, plate-like, and spherical) and three different oils (kerosene, bean oil, and pump oil) were used to model inclusions and slags, respectively. The effects of inclusion geometry (shape and size) and slag properties (viscosity and interfacial tension) on the separation process were investigated. The results revealed that the variation of surface free energy and the viscosity of the slag are two significant factors affecting the separation process of inclusions at the steel-slag interface. The variation of surface free energy helped inclusions enter the slag phase, whereas the decrease of slag viscosity shortened the separation time. The deformation of the steel-slag interface could give rise to the resistance force, which would resist inclusions passing through the interface. A liquid film formed on the inclusion as it passed through the steel-slag interface, which might be related to the inclusion's shape.

研究论文

Effect of cryogenic rolling and annealing on the microstructure evolution and mechanical properties of 304 stainless steel

Jin-tao Shi, Long-gang Hou, Jin-rong Zuo, Lin-zhong Zhuang, Ji-shan Zhang

2017, 24(6): 638-645. doi: 10.1007/s12613-017-1446-x

中文摘要(524) PDF(22) SpringerLink

摘要:
Metastable 304 austenitic stainless steel was subjected to rolling at cryogenic and room temperatures, followed by annealing at different temperatures from 500 to 950℃. Phase transition during annealing was studied using X-ray diffractometry. Transmission electron microscopy and electron backscattered diffraction were used to characterize the martensite transformation and the distribution of austenite grain size after annealing. The recrystallization mechanism during cryogenic rolling was a reversal of martensite into austenite and austenite growth. Cryogenic rolling followed by annealing refined grains to 4.7 μm compared with 8.7 μm achieved under room-temperature rolling, as shown by the electron backscattered diffraction images. Tensile tests showed significantly improved mechanical properties after cryogenic rolling as the yield strength was enhanced by 47% compared with room-temperature rolling.

研究论文Open Access

Comparative study on the corrosion behavior of X52, 3Cr, and 13Cr steel in an O₂-H₂O-CO₂ system:products, reaction kinetics, and pitting sensitivity

Bing-wei Luo, Jie Zhou, Peng-peng Bai, Shu-qi Zheng, Teng An, Xiang-li Wen

2017, 24(6): 646-656. doi: 10.1007/s12613-017-1447-9

中文摘要(611) PDF(19) SpringerLink

摘要:
The corrosion behaviors of X52, 3Cr low-alloy steel, and 13Cr stainless steel were investigated in an O₂-H₂O-CO₂ environment at various temperatures and O₂-CO₂ partial-pressure ratios. The results showed that the corrosion rates of X52, 3Cr, and 13Cr steels increased with increasing temperature. The corrosion rates slowly increased at temperatures less than 100℃ and increased sharply when the temperature exceeded 100℃. In the absence of O₂, X52, 3Cr, and 13Cr exhibited uniform corrosion morphology and FeCO₃ was the main corrosion product. When O₂ was introduced into the system, various forms of Fe₂O₃ appeared on the surface of the samples. The Cr content strongly influenced the corrosion resistance. The 3Cr steel with a low Cr content was more sensitive to pitting than the X52 or 13Cr steel. Thus, pitting occurred on the surface of 3Cr when 1.25 MPa of O₂ was added; this phenomenon is related to the non-uniform distribution of Cr in 3Cr.

研究论文Open Access

Simulation of jet-flow solid fraction during spray forming

Zi-qiang Pi, Xin Lu, Yuan Wu, Lu-ning Wang, Cheng-chang Jia, Xuan-hui Qu, Wei Zheng, Li-zhi Wu, Qing-li Shao

2017, 24(6): 657-669. doi: 10.1007/s12613-017-1448-8

中文摘要(553) PDF(11) SpringerLink

摘要:
A numerical model was developed to simulate the jet-flow solid fraction of W18Cr4V high-speed steel during spray forming. The whole model comprises two submodels:one is an individual droplet model, which describes the motion and thermal behaviors of individual droplets on the basis of Newton's laws of motion and the convection heat transfer mechanism; the other is a droplet distribution model, which is used to calculate the droplet size distribution. After being verified, the model was used to analyze the effects of parameters, including the initial gas velocity, deposition distance, superheat degree, and the ratio of gas-to-metal mass flow rates, on the jet-flow solid fraction. Finally, an equation to predict the jet-flow solid fraction directly and conveniently according to the parameters was presented. The values predicted by the equation show good agreement with those calculated by the numerical model.

研究论文

Effect of rare earth and alloying elements on the thermal conductivity of austenitic medium manganese steel

Shao-chun Chen, Hong-xiang Ye, Xin-qiang Lin

2017, 24(6): 670-674. doi: 10.1007/s12613-017-1449-7

中文摘要(547) PDF(24) SpringerLink

摘要:
The influence of different contents of Cr, Mo, and rare earth element (RE) additives on the thermal conductivity of austenitic medium manganese steel was studied and discussed. The results show that the addition of Cr in medium manganese steel can improved the ordering of C-Mn atomic clusters, so as to improve the steel's thermal conductivity. However, Cr will lead to precipitation of a great deal of carbides in medium manganese steel when its content is greater than 4wt%. These carbides would aggregate around the grain boundary, and as a result, the thermal conductivity is decreased. By the addition of Mo whose content is about 2wt%, spherical carbides will be formed, thus improving the thermal conductivity of the medium manganese steel. The interaction between rare earth elements and alloying elements will raise both the thermal conductivity and the wear-resisting property of medium manganese steel.

研究论文

Effect of oxygen partial pressure and transparent substrates on the structural and optical properties of ZnO thin films and their performance in energy harvesters

Yan-ping Xia, Pei-hong Wang, Shi-wei Shi, Gang He, Miao Zhang, Jian-guo Lü, Zhao-qi Sun

2017, 24(6): 675-680. doi: 10.1007/s12613-017-1450-1

中文摘要(429) PDF(10) SpringerLink

摘要:
Zinc oxide (ZnO) thin films were deposited onto different substrates-tin-doped indium oxide (ITO)/glass, ITO/polyethylene naphthalate (PEN), ITO/polyethylene terephthalate (PET)-by the radio-frequency (RF) magnetron sputtering method. The effect of various O₂/(Ar+O₂) gas flow ratios (0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) was studied in detail. ZnO layers deposited onto ITO/PEN and ITO/PET substrates exhibited a stronger c-axis preferred orientation along the (0002) direction compared to ZnO deposited onto ITO/glass. The transmittance spectra of ZnO films showed that the maximum transmittances of ZnO films deposited onto ITO/glass, ITO/PEN, and ITO/PET substrates were 89.2%, 65.0%, and 77.8%, respectively. Scanning electron microscopy (SEM) images of the film surfaces indicated that the grain was uniform. The cross-sectional SEM images showed that the ZnO films were columnar structures whose c-axis was perpendicular to the film surface. The test results for a fabricated ZnO thin film based energy harvester showed that its output voltage increased with increasing acceleration of external vibration.

研究论文

Studies on thermally grown oxide as an interface between plasma-sprayed coatings and a nickel-based superalloy substrate

Adam Khan Mahaboob Basha, Sundarrajan Srinivasan, Natarajan Srinivasan

2017, 24(6): 681-690. doi: 10.1007/s12613-017-1451-0

中文摘要(445) PDF(10) SpringerLink

摘要:
A thermally grown oxide layer formed by hot corrosion was investigated as an interface between plasma-sprayed coatings and a nickel-based superalloy substrate. The hot corrosion mechanism of NiCr-Cr₂O₃ and Al₂O₃-40wt% TiO₂ (A40T) plasma coated Inconel 617 was evaluated. The experiments were carried out at 1000℃ using a combination of Na₂SO₄, NaCl, and ₂O₅ salts to simulate the conditions of a gas turbine in a marine environment. The hot corrosion results revealed the spallation and dissolution of oxides upon prolonged exposure. Optical images and scanning electron micrographs of the exposed samples revealed the formation of oxide scale and provided details of its morphology in NiCr-Cr₂O₃ coated samples. Microstructure characterization of A40T coatings demonstrated a thermally grown oxide (TGO) layer at 1000℃. Increasing the thickness of the TGO layer decreased the corrosion resistance. The elemental analysis and image mapping revealed the migration of active elements from the substrate and coatings toward the corrosive environment.

研究论文Open Access

Investigation of rheo-diecasting mold filling of semi-solid A380 aluminum alloy slurry

Zhi-yong Liu, Wei-min Mao, Wei-pan Wang, Zhi-kai Zheng, Rui Yue

2017, 24(6): 691-700. doi: 10.1007/s12613-017-1452-z

中文摘要(482) PDF(27) SpringerLink

摘要:
The rheo-diecasting mold filling capacity and the microstructure of the semi-solid A380 aluminum alloy slurry were investigated. The results show that the mold filling capacity was strengthened with increasing pouring temperature or increasing injection pressure. Under certain process parameters, the mold cavity was fully filled. However, the mold filling capacity decreased with increasing holding time. The mold filling capacity was improved with increasing shape factor of primary α(Al) grains; however, the solid fraction and the grain size significantly increased at the same time. In addition, the microstructures along the route of the spiral samples obviously differed. The grain size decreased gradually from the near-end to the far-end, whereas the shape factor increased gradually.

研究论文

Low-frequency damping behavior of closed-cell Mg alloy foams reinforced with SiC particles

Wen-zhan Huang, Hong-jie Luo, Yong-liang Mu, Hao Lin, Hao Du

2017, 24(6): 701-707. doi: 10.1007/s12613-017-1453-y

中文摘要(502) PDF(18) SpringerLink

摘要:
The damping properties of an Mg alloy foam and its composite foams were investigated using a dynamic mechanical thermal analyzer. The results show that the loss factors of both the Mg alloy and its composite foams are insensitive to temperature and loading frequency when the temperature is less than a critical temperature T_crit. However, it increases when the temperature exceeds the T_crit values, which are 200 and 250℃ for the Mg alloy foam and the Mg alloy/SiC_p composite foams, respectively. The Mg alloy/SiC_p composite foams exhibit a higher damping capacity than the Mg alloy foam when the temperature is below 200℃. By contrast, the Mg alloy foam exhibits a better damping capacity when the temperature exceeds 250℃. The variation in the damping capacity is attributed to differences in the internal friction sources, such as the characteristics of the matrix material, abundant interfaces, and interfacial slipping caused by SiC particles, as well as to macrodefects in the Mg alloy and its composite foams.

研究论文

Glass-forming ability, microhardness, corrosion resistance, and dealloying treatment of Mg_60-xCu₄₀Nd_x alloy ribbons

Hao-yi Chi, Zhen-gui Yuan, Yan Wang, Min Zuo, De-gang Zhao, Hao-ran Geng

2017, 24(6): 708-717. doi: 10.1007/s12613-017-1454-x

中文摘要(510) PDF(8) SpringerLink

摘要:
The influence of Nd addition on the glass-forming ability (GFA), microhardness, and corrosion resistance of Mg_60-xCu₄₀Nd_x (x=5, 10, 15, 20, and 25, at%) alloys were investigated by differential scanning calorimetry, Vickers-type hardness tests, and electrochemical methods. The results suggest that the GFA and microhardness of the amorphous alloys increase until the Nd content reaches 20at%. The corrosion potential and corrosion current density obtained from the Tafel curves indicate that the Mg₃₅Cu₄₀Nd₂₅ ternary alloy exhibits the best corrosion resistance among the investigated alloys. Notably, nanoporous copper (NPC) was synthesized through a single-step dealloying of Mg_60-xCu₄₀Nd_x (x=5, 10, 15, 20, and 25) ternary alloys in 0.04 mol·L^-1 H₂SO₄ solution under free corrosion conditions. The influence of dealloying process parameters, such as dealloying time and temperature, on the microstructure of the ribbons was also studied using the surface diffusivity theory. The formation mechanism of dealloyed samples with a multilayered structure was also discussed.

研究论文

A strategy to obtain a high-density and high-strength zirconia ceramic via ceramic injection molding by the modification of oleic acid

Jia-xin Wen, Tian-bin Zhu, Zhi-peng Xie, Wen-bin Cao, Wei Liu

2017, 24(6): 718-725. doi: 10.1007/s12613-017-1455-9

中文摘要(546) PDF(14) SpringerLink

摘要:
Despite its unique high efficiency and good environmental compatibility, the water-soluble binder system still encounters problems achieving a desired sintered part via ceramic injection molding because of the poor compatibility and the powder-binder segregation between ceramic powders and binders. The objective of this study was to obtain a sintered part with excellent properties by introducing a small quantity of oleic acid to the surface of zirconia powders before the mixing process. As opposed to many previous investigations that focused only on the rheological behavior and modification mechanism, the sintering behavior and densification process were systematically investigated in this study. With the modified powders, debound parts with a more homogeneous and smaller pore size distribution were fabricated. Also, a higher density and greater flexural strength were achieved in the sintered parts fabricated using the modified powders.

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2017年第24卷第6期