International Journal of Minerals, Metallurgy and Materials

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Multi-factor sensitivity analysis of shallow unsaturated clay slope stability

2005, 12(3): 193-202.

中文摘要(271) PDF(7) SpringerLink

摘要:
An unsaturated clay slope, with various sloping angles and a thickness of 14 m, consists of backfill, slope soil and residual soil. Slide interfaces were determined by geophysical approaches and the original slope was reconstructed. Sub-slope masses were classified based on the varieties of sloping angle. A force recursive principle was proposed to calculate the stability coefficient of the sub-slope masses. The influencing factors such as sloping angle, water content, hydrostatic pressure, seismic force as well as train load were analyzed. The range and correlation of the above-mentioned factors were discussed and coupled wave equations were established to reflect the relationships between unit weight, cohesion, internal frictional angle, and water content, as well as between internal frictional angle and cohesion. The sensitivity analysis of slope stability was carried out and susceptive factors were determined when the factors were taken as independent and dependent variables respectively. The results show that sloping angle, water content and earthquake are the principal susceptive factors influencing slope stability. The impact of hydrostatic pressure on slope stability is similar to the seismic force in quantity. Train load plays a small role in slope stability and its influencing only reaches the roadbed and its neighboring slope segment. If the factors are taken as independent variables, the influencing extent of water content and cohesion on slope stability can be weakened and train load can be magnified.

Mineral

Application of marching cubes algorithm in visualization of mineral deposits

Dewen Seng, Zhongxue Li, Cuiping Li, Chunmin Li

2005, 12(3): 203-207.

中文摘要(428) PDF(13) SpringerLink

摘要:
An implementation scheme of the marching cubes (MC) algorithm was presented for the visualization of mineral deposits.The basic principles, processes and pitfalls of the MC algorithm were discussed. The asymptotic decider algorithm was employed to solve the ambiguity problem associated with the MC algorithm. The implementation scheme was applied to model and reconstruct the surfaces of mineral deposits, using the geological data obtained from an iron mine in China. Experimental results demonstrate the ability of the implementation scheme to solve the ambiguity problem, and illustrate the effectiveness and efficiency of the MC algorithm in the visualization of mineral deposits.

Mineral

A series of aminoamides used for flotation of kaolinite

Shimin Zhao, Dianzuo Wang, Yuehua Hu, Jing Xu, Xiaoling Zhao

2005, 12(3): 208-212.

中文摘要(356) PDF(7) SpringerLink

摘要:
N-(2-aminoethyl)-dodecanamide, N-(3-dimethylaminopropyl)-dodecanamide, and N-(3-diethylaminoproyl)-dodecanamide used as collectors were studied for the flotation of kaolinite in the absence of additives at different pulp phs as well as different collector contents. The effectiveness of the long chain aminoamides on pure kaolinite was demonstrated in laboratory scale flotation tests. The adsorption mechanism of the aminoamides onto kaolinite was investigated through zeta potential determinations and infrared spectrometry. The -98 μm size fractions of kaolinite, taken from Jiaxian Henan of China, were used in flotation. The hydrophilic group size of the aminoamides has a relatively less influence upon the floatability of pure kaolinite. The results suggest either the static-electric force or the coordinating bond adsorption mechanism of the aminoamides onto kaolinite depends on pulp pH.

Metallurgy

Thermodynamic properties and mixing thermodynamic parameters of two-phase metallic melts

Jian Zhang

2005, 12(3): 213-220.

中文摘要(240) PDF(6) SpringerLink

摘要:
Based on the calculating model of metallic melts involving eutectic, the calculating equations of mixing thermodynamic parameters for two phase metallic melts have been formulated in the light of those equations of homogeneous solutions. Irrespective as to whether the activity deviation relative to Raoultian behavior is positive or negative, or the deviation is symmetrical or unsymmetrical, the evaluated results not only agree well with experimental values, but also strictly obey the mass action law. This testifies that these equations can authentically reflect the structural reality and mixing thermodynamic characteristics of two-phase metallic melts. The calculating equations of mixing thermodynamic parameters for the model of two phase metallic melts offer two practical criteria (activity and mixing thermodynamic parameters) and one theoretical criterion (the mass action law).

Metallurgy

Viscosity estimation for slags containing calcium fluoride

Qifeng Shu, Jiayun Zhang

2005, 12(3): 221-224.

中文摘要(373) PDF(33) SpringerLink

摘要:
Based on recently published experimental data, the Riboud model was modified for viscosity estimation of the slags containing calcium fluoride. The estimated values were in good agreement with measured data. Reasonable estimation can be achieved using the modified Riboud model for mould fluxes and ESR (eletro slag remelting) slags. Especially for ESR slags, the modified Riboud model can provide much more precise values than the original Riboud model.

Metallurgy

Effect of components on desulfurization of an Al₂O₃-CaO base pre-molten slag containing SrO

Heming Zhao, Xinhua Wang, Bing Xie

2005, 12(3): 225-230.

中文摘要(247) PDF(11) SpringerLink

摘要:
The desulfurization experiment of an Al₂O₃-CaO base pre-molten refining slag containing SrO was carried out. Experimental samples were made from industrial materials. In order to predict the slag's desulfurization ability, sulphur capacity was calculated by means of optical basicity, and there is consistency between calculated results and experimental data. A mathematical model between components and sulphur partition ratio was established with the experimental data. Based on the regression equation,the effects of single and interactive components on sulphur partition ratio were discussed. The results show that the sulphur capacity and distribution ratio decrease with the increment of Al₂O₃/CaO. SrO and MgO can increase the sulphur partition ratio. The best content of SrO in the slag should not be more than 10%, and the MgO content should be about 8%. The effect of CaF₂ on sulphur partition ratio is not obvious, therefore the addition should be limited for environmental protection.

Materials

Melt nucleating and the three-dimension steady model of the temperature fluctuation with convection

Mingwen Chen, Renji Sun, Zidong Wang, Fengying Wang

2005, 12(3): 231-235.

中文摘要(238) PDF(3) SpringerLink

摘要:
A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series form. It theoretically confirms the mechanism of melt nucleating: as long as the convection with transverse directions exists, the melt temperature on the front of the solidliquid interface would be not only periodical along the direction which is perpendicular to the direction of crystal growth, but also oscillatory and exponential decay along the direction of crystal growth; this oscillatory property, i.e. temperature fluctuation, leads to local supercooling, accelerates local temperature fluctuation and then results in a large number of nuclei.

Materials

Frequency-dependent dynamic effective properties of porous materials

Peijun Wei, Zhuping Huang

2005, 12(3): 236-242.

中文摘要(282) PDF(4) SpringerLink

摘要:
The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.

Materials

Microstructures of spinodal phases in Cu-15Ni-8Sn alloy

Yanhui Wang, Mingpu Wang, Bin Hong

2005, 12(3): 243-247.

中文摘要(348) PDF(11) SpringerLink

摘要:
The microstructures of spinodal phases in Cu-15Ni-8Sn alloy were studied by TEM. It was found that when the alloy is completely in a as-quenched state, spinodal decomposition is quick. Ordering appears after spinodal decomposition. The ordered phase with DO₂₂ structure has three variants obtained from coarsening spinodal structure. The reason of ordering appeared after spinodal decomposition is that the content of solute atoms needed by ordering is higher than the average, which can be reached by the composition fluctuation of spinodal decomposition. It was speculated that the morphology of the ordered phase is needle-like.

Materials

Over-relaxation effect of deformed austenite on ageing behavior of an Nb-bearing microalloyed steel

Shaoqiang Yuan, Shanwu Yang, Xuemin Wang, Xinlai He

2005, 12(3): 248-251.

中文摘要(269) PDF(4) SpringerLink

摘要:
The ageing behavior of an Nb-bearing microalloyed steel at 525℃ was investigated by thermo-simulation test, hardness measurements and transmission electron microscopy （TEM）. Prior to ageing, the steel was deformed in austenite zone followed by a long relaxation. Experimental results indicate that the hardness decreases gradually in the initial stage until ageing for 120 min, and then increases continuously until 1200 min. The coarsened precipitates （>10 nm） formed in deformed austenite remain nearly unchanged in size, even after ageing for long time, while the further precipitates, which nucleate in a phase, contribute to the increasing of hardness. By comparison, the undeformed samples in austenite subjected to the same ageing process display a very similar hardness change trend to that of over-relaxacion ones and have higher hardness values at each corresponding period.

Materials

Alloying elements characterization in a Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-1Nd titanium alloy by carbon addition

Shangzhou Zhang, Huizhong Xu, Ziquan Liu, Huilu Li, Rui Yang

2005, 12(3): 252-256.

中文摘要(311) PDF(6) SpringerLink

摘要:
The effects of carbon addition (0.01wt%-0.43wt%) on a Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-1Nd (wt%) alloy with a bimodal microstructure were investigated. Electron probe microanalysis was carried out to examine the partitioning behavior of carbon and the relation of carbon content to the distributions of Al and Mo in the primary α phase (α_p) and β transformed structure (β). It was found that interstitial carbon is enriched in the α_p phase and its content slightly reduces with the increase of the volume fraction of α_p.The measurements of carbon content in the present alloy with an α_p of 15vol% showed that the carbon content in the α_p phase increases with the increment of carbon addition until a maximum but keeps almost constant in the β phase. The addition of carbon reduces the solubility of Al and Mo in the α_p phase and leads to the increment of Mo partitioning to the β phase. When the carbon content is over 0.17wt% (0.67at%), carbide precipitation occurs in the matrix and its volume fraction is related to the volume fraction of α_p which can be explained in term of the difference of carbon solubility in the α_p and β phases.

Materials

Effects of small amount Ta on the characteristics of the Zr-Al-Ni-Cu-Ta bulk metallic glass

Hongchao Kou, Xidong Hui, Xiongjun Liu, Xiping Song, Guoliang Chen, Kefu Yao

2005, 12(3): 257-261.

中文摘要(277) PDF(6) SpringerLink

摘要:
The effects of Ta on the characteristics of the Zr-base BMG (bulk metallic glass) were investigated. Zr₅₅Al₁₀Ni₅Cu_30-xTa_x (x=1, 2,4) bulk metallic glasses (BMGs) with 3.5 mm diameter and 70 mm length were successfully prepared by using combined jet and copper mold casting. A small amount of Ta addition does not change the glass transition temperature, crystallization temperature,and supercooled liquid region obviously, but Ta promotes composition separation and two-stage crystallization. The stable crystalline phases include Zr₂Ni, CuZr₂, Al₂Zr₃ intermetallic compounds and Ta-rich solid solution after annealing the Zr-Al-Ni-Cu-Ta alloys at 753 K. Zr₅₅Al₁₀Ni₅Cu_30-xTa_x (x=1,2,4) bulk glassy alloys exhibit a better compressive strength. The stress-strain curve shows a zigzag feature, and the fracture surface shows intersecting of shear bands. It may correlate with the inhomogeneous feature of amorphous structure.

Materials

Kinetic equation for internal oxidation of Cu-Al alloy cylinders

Kexing Song, Jiandong Xing, Baohong Tian, Ping Liu, Qiming Dong

2005, 12(3): 262-266.

中文摘要(331) PDF(10) SpringerLink

摘要:
The kinetics of internal oxidation of Cu-Al alloy cylinders, containing up to 2.214mol% Al, were investigated in the temperature range of 1023 K to 1273 K, and the depth of internal oxidation was measured in the microscopy. A kinetic equation was derived to describe the internal oxidation of Cu-Al alloy cylinders. For the internal oxidation of Cu-Al alloys employed in the synthesis of alumina dispersion strengthened copper, the kinetic equation can be simplified. The derived equation was checked experimentally by means of oxidation depth measurements and the results show that the derived equation is exact enough to describe the kinetics of internal oxidation of Cu-Al alloy cylinders. Based on this equation and the oxidation depth measurements, the permeability of oxygen in solid copper was obtained. Investigation also shows that there is no evidence for preferential diffusion along grain boundaries in the process of internal oxidation.

Materials

Performance of a 60 F carbon nanotubes-based supercapacitor for hybrid power sources

Xiaofeng Wang, Dianbo Ruan, Zheng You, Yiqiang Lu, Qiqian Sha

2005, 12(3): 267-273.

中文摘要(366) PDF(4) SpringerLink

摘要:
A supercapacitor based on charge storage at the interface between a high surface area carbon nanotube electrode and a LiClO₄/PC electrolyte was assembled. The performance of the capacitor depends on not only the material used in the cell but also the construction of the cell. From a constant charge-discharge test, the capacitance of 60 F was obtained. The performance of the power capacitor for pulse power sources was described. The specific energy (0.8 W·h·kg^-1) and the specific power (0.75 kW·kg^-1) of the power supercapacitor were demonstrated with a cell of the maximum operating voltage of 2.5 V. A hybrid power source consisting of a lithium ionic battery and the 60 F supercapacitor was demonstrated to power successfully a simulated power load encountered in GSM portable communication equipment. The addition of the supercapacitor to the power train of a cellular phone results in significantly more energy from the battery being used by the load. The experiments indicate that more than 33.8% energy is utilized by load and less stored energy is dissipated within the battery for each charge-discharge cycle.

Materials

Structure characteristics and electrochemical properties of LiMn₂O₄ modified by LiCoO₂

Zhenping Cai, Mingxun Li, Shigang Lu, Weihua Jin

2005, 12(3): 274-276.

中文摘要(436) PDF(11) SpringerLink

摘要:
In order to improve the cycle performance of LiMn₂O₄, the modified LiMn₂O₄ was prepared by solid-state reactions using LiMn₂O₄ and LiCoO₂ as precursors. XRD and EDS were used to study the structure properties of the modified LiMn₂O₄. The electrochemical properties of the modified LiMn₂O₄ were also investigated. The results show that Li and Co atoms could insert into the LiMn₂O₄ crystal lattice and a newly formed spinel phase, modified LiMn₂O₄ was obtained. The modified LiMn₂O₄ exhibits excellent cycle ability at room and elevated temperatures compared to pure LiMn₂O₄. The improved electrochemical stability of the modified LiMn₂O₄ attributes to the entrance of Li and Co ions inserted into the spinel crystal structure.

Materials

Fine grain tungsten produced with nanoscale powder

Tao Lin, Fang Zhao, Liying Zhang, Chengyi Wu, Zhimeng Guo

2005, 12(3): 277-280.

中文摘要(356) PDF(10) SpringerLink

摘要:
Nanoscale tungsten powder was prepared by reducing nanoscale tungsten trioxide in hydrogen to WO_2.90 and further to W powder. After compacted with a rubber die, the nanoscale tungsten powder was sintered in a high-temperature dilatometer to investigate its shrinkage process. The results show that the compact of the nanoscale tungsten powder starts to shrink at 1050℃ and ends at 1500℃. The shrinkage rate reaches the maximum value at 1210℃. The relative density of sintered samples is 96.4%, and its grain size is about 5.8 μm.

Materials

KDD-based rolling schedule model for plate mill

Zhichun Mu, Dangxian Ma, Shaobo Wang, Changsong Wang

2005, 12(3): 281-285.

中文摘要(320) PDF(4) SpringerLink

摘要:
A novel method for generating a rolling schedule is presented, which is fundamentally different from the existing ones.KDD (knowledge discovery in database) techniques are applied for discovering association rules between rolling parameters in a large database of rolling operation, and based on these rules, the schedule for the crucial last six finishing passes is generated. Operational evaluation shows that the schedule generated by the new method outperforms that generated by existing methods. It also shows how in this application the human's domain knowledge is applied to speed up the KDD process and to ensure the validity of the knowledge discovered.

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2005年第12卷第3期