International Journal of Minerals, Metallurgy and Materials

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GIS-based 3D limit equilibrium analysis for design optimization of a 600 m high slope in an open pit mine

2007, 14(1): 1-5. doi: 10.1016/S1005-8850(07)60001-2

中文摘要(240) PDF(12) SpringerLink

摘要:
Combining the GIS (geographic information systems) grid-based data with four proposed column-based 3D slope stability analysis models, a comprehensive solution of a high-steep open-pit slope has been obtained. For six searching ranges, 19 critical slip surfaces of different sizes have been studied, in which the minimum 3D safety factor is 1.33. Comparison of 3D safety factors of designed and proposed slope plans shows for all the critical slip surfaces for the proposed plan, the smallest 3D safety factor is 1.33 under the most unfavorable condition. This means that the proposed plan of the high slopes, about 600 m, of an open pit (2-5° steeper than designed plan) is feasible.

Mineral

Application of a microseismic monitoring system in deep mining

Chengxiang Yang, Zhouquan Luo, Guobin Hu, Xiaoming Liu

2007, 14(1): 6-8. doi: 10.1016/S1005-8850(07)60002-4

中文摘要(276) PDF(20) SpringerLink

摘要:
A microseismic monitoring system was used in the Donggua Shan underground copper mine, and its application was introduced. The spacial distribution of the seismic event was monitored effectively during mining with this system. The distribution of the seismic intensity in different time periods and in the different mining districts was obtained via the clustering analysis of the monitored results, and the different intensity concentration districts of seismicity were compartmentalized. The various characteristics and waveforms of different vibrations in the underground mine were revealed with the help of the micro-seismic monitoring system. It was proved that the construction and application of the micro-seismic monitoring system in the mine not only realized the continuous monitoring of seismicity in the deep mine, but also settled an this system.

Mineral

A new synthetic chelating collector for the flotation of oxidized-lead mineral

Yongkai Zhu, Chuanyao Sun, Weiguo Wu

2007, 14(1): 9-13. doi: 10.1016/S1005-8850(07)60003-6

中文摘要(248) PDF(10) SpringerLink

摘要:
A new synthetic reagent DPTUHP [diphenyl α-(3-phenylthioureido) hexylpbosphonate] containing a hydrocarbon chain nonpolar group, a thioureido, and a phosphonate easter chelating group, has proven to be an effective collector for the flotation of cerussite mineral. The synthetic method utilized the Mannich-type reaction of an N-monosubstituted thiourea, an aldehyde, and triphenyl phosphate in glacial acetic acid solution. The experimental results of flotation of the cerussite mineral show that the collector has stronger collecting ability and higher selectivity in a neutral and a slightly alkaline medium, especially in the pulp of pH=8. Using the measurements by infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) of the cerussite mineral, the collector, as well as the cerussite treated with the collector, the flotation mechanism of cerussite has been discussed. It is concluded that the adsorption of collector on cerussite is a chemical adsorption through the electron donor atoms of the collector chelating the Pb (Ⅱ) of cerussite to form chelate.

Metallurgy

Thermodynamic calculations and experiments on inclusions to be nucleation sites for intragranular ferrite in Si-Mn-Ti deoxidized steel

Xiaojun Zhuo, Xinhua Wang, Wanjun Wang, Lee Hae-Geon

2007, 14(1): 14-21. doi: 10.1016/S1005-8850(07)60004-8

中文摘要(285) PDF(10) SpringerLink

摘要:
Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron microscope (FE-SEM) with energy dispersive X-ray spectrometry (EDS). The kind and composition of the inclusions calculated from the thermodynamic database were in good agreement with the experimental results. There were two main kinds of inclusions formed in the Si-Mn-Ti deoxidized steels. One kind of inclusion was the manganese titanium oxide (Mn-Ti oxide). Another kind of inclusion was the MnS inclusion with segregation points containing Ti and N. According to the thermodynamic calculation, those segregation points were TiN precipitates. The formation of intragranular ferrite (IGF) microstructures refined the grain size during the austenite-ferrite transformation. The mechanisms of IGF formation were discussed. Mn-Ti oxide inclusions with Mn-depleted zone (MDZ) were effective to be nucleation sites for IGF formation, because the MDZ increased the austenite-ferrite transformation temperature. TiN had the low misfit ratio with IGF, so the TiN precipitated on the MnS surface also promoted the formation of IGF because of decreasing interfacial energies.

Metallurgy

Mathematical modeling of fluid flow, heat transfer and inclusion transport in a four strand tundish

Yufeng Wang, Guanghua Wen, Ping Tang, Mingmei Zhu, Yuanqing Chen, Weizhao Song

2007, 14(1): 22-26. doi: 10.1016/S1005-8850(07)60005-X

中文摘要(313) PDF(9) SpringerLink

摘要:
Mathematical simulation was used for trouble-shooting and optimization. By the mathematical simulation, fluid flow and beat transfer of molten-steel in a four-strand tundish of a billet caster under different conditions (bare tundish and tundish with flow control device) were analyzed, The results showed that (1) the tundish with flow control device (FCD) has an important effect on the fluid pattern and temperature distribution; (2) the unsteady, solving method was used to model the inclusion motions at different time perthds, and it showed that the FCD is advantageous to separate the nonmetallic inclusions. According to the simulation results, the main problem existing in the industry preduction was found, and some helpful rneasurements were executed. Consequently, the large nonmetallic inclusions were separated, and the content of total oxygen was reduced. The qualily of steel was greatly improved.

Metallurgy

Improvement of fuel consumption and maintenance of heating furnaces using a modified heating pattern

Hsun-Heng Tsai, Shiuh-Ming Chang

2007, 14(1): 27-32. doi: 10.1016/S1005-8850(07)60006-1

中文摘要(169) PDF(10) SpringerLink

摘要:
This article studies the transient heat conduction in a slab when passing through various sections of the furnace, and focuses on the thickness of the scale layer formed on the slab. The transient heat conduction behavior of a slab in various sections of the heating furnace is analyzed using the Laplace transformation method, including the pre-heating zone, the first heating zone, the second heating zone, and the soaking zone. The heating pattern of the furnace is then modified to reduce fuel consumption. The simulation results show that the scale layer formed on the slab significantly influences the quality of the hot rolled coil formed, and how the furnace parameters affect the efficiency of the furnace and the quality of the coil.

Metallurgy

A numerical method for solving the boundary layer equations of laminar natural convention about a vertical plate

Liancun Zheng, Chen Liang, Xinxin Zhang

2007, 14(1): 33-35. doi: 10.1016/S1005-8850(07)60007-3

中文摘要(217) PDF(34) SpringerLink

摘要:
An improved shooting method was presented for solving the natural convention boundary layer equations, with a coupling of the velocity field to the temperature field. The numerical results are consistent with the approximate solution obtained by former researchers.

Materials

Characteristics of microstructural evolution during deformation-enhanced ferrite transformation in Nb-microalloyed HSLA steel

Guoan Chen, Wangyue Yang, Shouzhen Guo, Zuqing Sun

2007, 14(1): 36-40. doi: 10.1016/S1005-8850(07)60008-5

中文摘要(191) PDF(11) SpringerLink

摘要:
Microstructure evolution during deformation of undercooled austenite at 760℃ was investigated in Nb-microalloyed steel by using SEM (scanning electron microscope), TEM (transmission electron microscope), and EBSD (electron backscattered diffraction). It is indicated that during deformation-enhanced ferrite transformation (DEFT) in Nb-microalloyed steel, the incubation period is prolonged, and the higher strain is needed to accomplish ferrite transformation. Therefore, the transformation kinetics curves move to high strain parallelly; and the transformation kinetics curves of Nb-microalloyed steel can be divided into three stages. At the fast stage, the solute drag effect of Nb and the consumption of strain energy for the dynamic precipitation of Nb(CN) led to a long incubation period, and at the second stage, ferrite transformation was accelerated significantly and fine Nb(CN) precipitates restrict the grain growth of ferrite effectively. The results also showed that DEFT in Nb-microalloyed steel is still a nucleation dominated process, and during the microstructure evolution the interchange of 〈001〉 and 〈111〉 texture was obtained.

Materials

Optimized composition for bonding assistant coat in carbon steel sandwich panels

Jing Liu, Jingtao Han

2007, 14(1): 41-45. doi: 10.1016/S1005-8850(07)60009-7

中文摘要(224) PDF(8) SpringerLink

摘要:
On the basis of the alloying theory of bonding assistant coat (BAC), taking into account of the interaction of alloy elements, the regressive equation, which relates the wetting ability of bonding assistant coat with the contents of Mn, Ni, Si, Sn, and B, was es- tablished by using quadratic regression orthogonal design of five factors. The influence of elements and their interaction on the wetting ability was analyzed. The ranges of alloy elements were optimized. The melting point of bonding assistant coat was measured by using differential thermal analysis. The results show that the interactions of Ni and Mn, Ni, and Sn can increase the wetting ability obviously and the melting point of bonding assistant coat has been decreased.

Materials

Effect of solid-solution temperature on the microstructure of Fe-Ni based high strength low thermal expansion (HSLTE) alloy

Yifan Tu, Jin Xu, Jianfu Zhang, Boping Zhang, Dongliang Zhao

2007, 14(1): 46-51. doi: 10.1016/S1005-8850(07)60010-3

中文摘要(230) PDF(10) SpringerLink

摘要:
The influence of solid-solution temperature on the dissolution of carbide precipitates, the average grain size and the microhardness of the austenite matrix in an Fe-Ni based high strength low thermal expansion (HSLTE) alloy was investigated to obtain the proper temperature range of the solid-solution process. The XRD analysis, microstructure observations, and the theoretical calculations showed that the Mo-rich M₂C-type precipitates in the Fe-Ni based HSLTE alloy dissolve completely at about 1100℃. The average grain size of the studied alloys increases from 14 to 46 μm in the temperature range of 1050 to 1200℃. The microhardness of the matrix decreases gust for the sake of solid-solution treatment, but then increases later with increasing solution temperature because of the solution strengthening effect.

Materials

Isothermal corrosion Fe₃Si alloy in liquid zinc

Wenjun Wang, Junping Lin, Yanli Wang, Guoliang Chen

2007, 14(1): 52-55. doi: 10.1016/S1005-8850(07)60011-5

中文摘要(208) PDF(12) SpringerLink

摘要:
The isothermal corrosion testing, microscopic examination and the performance of Fe₃Si alloy as materials of construction for bath hardware in continuous hot-dipping lines were studied. The corrosion of Fe₃Si alloy in molten zinc was controlled by attacking the grain boundaries preferentially. Aluminum reacted with iron of Fe₃Si alloy firstly while the samples were immersed in molten zinc, although aluminum contents in the molten zinc were very low. The phase of reaction product was thought to be Fe₂Al₅. The corrosion rate of the Fe₃Si alloy in molten zinc was determined to be approximately 2.9×10^-3 mm/h, therefore the liquid zinc corrosion resistance of Fe₃Si alloy was very weak.

Materials

New method for the preparation of semi-solid AlSi7Mg alloy slurry

Weimin Mao, Hai Lin, Yuelong Bai, Songfu Gao

2007, 14(1): 56-60. doi: 10.1016/S1005-8850(07)60012-7

中文摘要(250) PDF(8) SpringerLink

摘要:
The effects of pouring temperature and short electromagnetic stirring with low strength on the microstructures of AlSi7Mg alloy were investigated. The results show that if liquid AlSi7Mg alloy is poured at 630 or 650℃, many primary α-Al grains in the solidified melt are rosette-like, and only a small number of them are spherical. However, if liquid AlSi7Mg alloy is poured at a lower superheat and meanwhile is stirred by an electromagnetic field at a low power for a short time, then most primary α-Al grains in the solidified melt become spherical, and only a few are rosette-like. The theoretical analysis indicates that the strengthened melt flow motion induced by the short electromagnetic stirring makes the temperature field more homogeneous in the melt, which is poured at a lower superheat, and makes the primary α-Al grains deposit in a larger region at the same time, so this new solidification kinetic condition leads to the microstructure of spherical primary α-Al grains. The experiments also demonstrate that pouring at an appropriate superheat and stirring by an electromagnetic field at a low power for a short time is a good new method for preparing the semi-solid slurry or billet of AlSi7Mg alloy.

Materials

Simulation of the precipitation process of Ni₇₅Al_xV_25-x alloys incorporated in the microelasticity field

Yongsheng Li, Zheng Chen, Yungang Li, Yanli Lu, Yongxin Wang

2007, 14(1): 61-66. doi: 10.1016/S1005-8850(07)60013-9

中文摘要(207) PDF(9) SpringerLink

摘要:
The microelasticity field was incorporated into the microscopic phase-field equation for the ternary alloy systems, the morphology evolution and coarsening behavior of the Ni₇₅Ai_xV_25-x alloy were simulated. The γ phase precipitates initially for Ni₇₅Al_7.1V_17.9 and Ni₇₅Al_5.5V_19.5 alloys and the two phases transform from the equiaxed or strip-like to the quadrate as the growth and coarsening processes. For the anisotropic elasticity interaction of the system, the orientation of γ is along the 〈001〉 directions and the θ phase is along the short axis direction of [10]. Analysis of the structure and the pair-correlation functions indicate that the average precipitate length scale of the particles increases at the late-stage coarsening, and the dynamical scaling behavior is obeyed.

Materials

Growth behavior of electroless copper on silicon substrate

Shin-Shyan Wu, Wei-Long Liu, Ting-Kan Tsai, Shu-Huei Hsieh, Wen-Jauh Chen

2007, 14(1): 67-71. doi: 10.1016/S1005-8850(07)60014-0

中文摘要(236) PDF(14) SpringerLink

摘要:
The growth behavior containing deposit morphology, growth rate, activation energy, and growth mechanism of copper on silicon substrate, especially at the initial stage, in the electroless plating process was studied. Copper was deposited on the surface of the silicon substrate in an electloless plating bath containing formalin (CH₂O 37vol%) as a reducing agent at a pH value of 12.5 and a temperature of 50-75℃. The copper deposit was characterized using a field emission scanning electron microscope and transmission electron microscope. The results showed that after the activation process, nanoscale Pd particles were distributed evenly on the surface of the silicon; in the deposition process, copper first nucleated at locations not only near the Pd particles but also between the Pd particles; the growth rate of electroless Cu ranged from 0.517 nm/s at 50℃ to 1.929 nm/s at 75℃. The activation energy of electroless Cu on Si was 52.97 kJ/mol.

Materials

Preparation of nanometer yellow iron and its UV absorption capacity

Chunbao Sun, Beihai Zhou, Nan Li, Ruiming Wang

2007, 14(1): 72-76. doi: 10.1016/S1005-8850(07)60015-2

中文摘要(264) PDF(10) SpringerLink

摘要:
The nanometer yellow iron oxide was prepared by oxidizing Fe(OH)2 with air, which was verified with XRD and TEM. The result shows that nanometer yellow iron oxide is spindle-shaped and well-distributed with a long axis of 150-200 nm and short axis of 40-50 nm. Ultraviolet (UV) transmittance of the iron oxide shows the great effect of concentration on both transparency and UV absorption, and it has been proven that iron oxide with a concentration of 0.025wt% is preferred. The spectrum of XRD indicates that it is goethite. When the yellow iron is dispersed in sol, given that the wavelength of UV is less than 300 nm, its UV absorption capacity is superior to those of ZnO and TiO₂. The absorption capacity of the yellow iron is less than TiO₂ and more than ZnO as the wavelength of UV is 300-400 nm.

Materials

Adsorption behavior of heavy metal ions by carbon nanotubes grown on microsized Al₂O₃ particles

Shu-Huei Hsieh, Jao-Jia Horng

2007, 14(1): 77-84. doi: 10.1016/S1005-8850(07)60016-4

中文摘要(360) PDF(9) SpringerLink

摘要:
Carbon nanotubes (CNTs) were grown on the surface of microsized Al₂O₃ particles in CH₄ atmosphere at 700℃ under the catalysis of Fe-Ni nanoparticles. The CNTs on Al₂O₃ were used for adsorbing Pb²⁺, Cu²⁺, and Cd²⁺ from the solution and the results were compared with active carbon powders, commercial carbon nanotubes, and Al₂O₃ particles. The as-grown CNTs/Al₂O₃ have demonstrated extraordinary absorption capacity with further treatment or oxidation, as well as hydrophilic ability that other CNTs lacked. The adsorption capacity of CNTs on Al₂O₃ is superior to other adsorbents and the preference order of adsorption on composite Al₂O₃ is pb²⁺ > Cu²⁺ > Cd²⁺. It seemed that the adsorption of those Pb²⁺, Cu²⁺, and Cd²⁺ did not change the surface properties of composite particles. The adsorption behaviors of Pb²⁺, Cu²⁺, and Cd²⁺ by CNTs on Al₂O₃ match well with the Langmuir isothermal adsorption model and the second order kinetic model. The calculated saturation amount adsorbed by 1 g of CNTs on Al₂O₃ are 67.11, 26.59, and 8.89 mg/g for Pb²⁺, Cu²⁺, and Cd²⁺ in single adsorption test, respectively.

Materials

Property of three-dimensional silica composites

Guangyao Jia, Zhimeng Guo

2007, 14(1): 85-88. doi: 10.1016/S1005-8850(07)60017-6

中文摘要(212) PDF(8) SpringerLink

摘要:
Silica fibers-reinforced, fused silica composites were fabricated with repeated vacuum-assisted liquid-phase infiltration. The mechanical properties, thermal properties, and ablative properties of the samples were evaluated. The effect of the silica fiber content and treatment temperature on the flexural strength of the three-dimensional SiO₂ (3-D SiO₂) composites also was investigated. The SiO₂ composites show good mechanical properties and excellent ablative performance. The flexural strength increases with an increase in silica fiber content, and decreases with an increase in treatment temperature. When the volume fraction of the silica fiber is 50vo1% and the treatment temperature is 700℃ the flexural strength of the composites reaches a maximum value of 78 MPa. By adding cyclohexanone surfactant, the infiltration property can be largely improved, resulting in the density of SiO₂ composites increasing up to 1.65 g/cm³. The fracture surfaces of the flexural specimens observed using SEM, show that the pseudoplasticity and the toughening mechanisms of the composites are caused by absorption of a lot of energy by interface debonding and fiber pulling out.

Materials

Sintering behavior, microstructure and properties of TiC-FeCr hard alloy

Farid Akhtar, Shiju Guo, Jawid Askari, Jianjun Tian

2007, 14(1): 89-93. doi: 10.1016/S1005-8850(07)60018-8

中文摘要(376) PDF(13) SpringerLink

摘要:
TiC based cermets were produced with FeCr, as a binder, by conventional P/M (powder metallurgy) to near 〉97% of the theoretical density. Sintering temperature significantly affects the mechanical properties of the composite. The sintering temperature of 〉1360℃ caused severe chemical reaction between TiC particles and the binder phase. In the TiC-FeCr cermets, the mechanical properties did not vary linearly with the carbide content. Optimum mechanical properties were found in the composite containing 57wt% TiC reinforcement, when sintered at 1360℃ for 1 h. Use of carbon as an additive enhanced the mechanical properties of the composites. Cermets containing carbon as an additive with 49wt% TiC exhibited attractive mechanical properties. The microstructure of the developed composite contained less or no debonding, representing good wettabifity of the binder with TiC particles. Homogeneous distribution of the TiC particles ensured the presence of isotropic mechanical properties and homogeneous distribution of stresses in the composite. Preliminary experiments for evaluation of the oxidation resistance of FeCr bonded TiC cermets indicate that they are more resistant than WC-Co hardmetals.

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