International Journal of Minerals, Metallurgy and Materials

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Upgrading and dephosphorization of Western Australian iron ore using reduction roasting by adding sodium carbonate

De-qing Zhu, Tie-jun Chun, Jian Pan, Li-ming Lu, Zhen He

2013, 20(6): 505-513. doi: 10.1007/s12613-013-0758-8

中文摘要(348) PDF(57) SpringerLink

摘要:
The technology of direct reduction by adding sodium carbonate (Na₂CO₃) and magnetic separation was developed to treat Western Australian high phosphorus iron ore. The iron ore and reduced product were investigated by optical microscopy and scanning electron microscopy. It is found that phosphorus exists within limonite in the form of solid solution, which cannot be removed through traditional ways. During reduction roasting, Na₂CO₃ reacts with gangue minerals (SiO₂ and Al₂O₃), forming aluminum silicate-containing phosphorus and damaging the ore structure, which promotes the separation between iron and phosphorus during magnetic separation. Meanwhile, Na₂CO₃ also improves the growth of iron grains, increasing the iron grade and iron recovery. The iron concentrate, assaying 94.12wt% Fe and 0.07wt% P at the iron recovery of 96.83% and the dephosphorization rate of 74.08%, is obtained under the optimum conditions. The final product (metal iron powder) after briquetting can be used as the burden for steelmaking by an electric arc furnace to replace scrap steel.

Direct reduction of iron ore by biomass char

Hai-bin Zuo, Zheng-wen Hu, Jian-liang Zhang, Jing Li, Zheng-jian Liu

2013, 20(6): 514-521. doi: 10.1007/s12613-013-0759-7

中文摘要(426) PDF(33) SpringerLink

摘要:
By using thermogravimetric analysis the process and mechanism of iron ore reduced by biomass char were investigated and compared with those reduced by coal and coke. It is found that biomass char has a higher reactivity. The increase of carbon-to-oxygen mole ratio (C/O) can lead to the enhancement of reaction rate and reduction fraction, but cannot change the temperature and trend of each reaction. The reaction temperature of hematite reduced by biomass char is at least 100 K lower than that reduced by coal and coke, the maximum reaction rate is 1.57 times as high as that of coal, and the final reaction fraction is much higher. Model calculation indicates that the use of burden composed of biomass char and iron ore for blast furnaces can probably decrease the temperature of the thermal reserve zone and reduce the CO equilibrium concentration.

Effect of carbon species on the reduction and melting behavior of boron-bearing iron concentrate/carbon composite pellets

Guang Wang, Yin-gui Ding, Jing-song Wang, Xue-feng She, Qing-guo Xue

2013, 20(6): 522-528. doi: 10.1007/s12613-013-0760-1

中文摘要(247) PDF(8) SpringerLink

摘要:
Iron nugget and boron-rich slag can be obtained in a short time through high-temperature reduction of boronbearing iron concentrate by carbonaceous material, both of which are agglomerated together as a carbon composite pellet. This is a novel flow sheet for the comprehensive utilization of boron-bearing iron concentrate to produce a new kind of man-made boron ore. The effect of reducing agent species (i.e., carbon species) on the reduction and melting process of the composite pellet was investigated at a laboratory scale in the present work. The results show that, the reduction rate of the composite pellet increases from bituminite, anthracite, to coke at temperatures ranging from 950 to 1300℃. Reduction temperature has an important effect on the microstructure of reduced pellets. Carbon species also affects the behavior of reduced metallic iron particles. The anthracite-bearing composite pellet melts faster than the bituminitebearing composite pellet, and the coke-bearing composite pellet cannot melt due to the high fusion point of coke ash. With anthracite as the reducing agent, the recovery rates of iron and boron are 96.5% and 95.7%, respectively. This work can help us get a further understanding of the new process mechanism.

Hot compression deformation behavior of AISI 321 austenitic stainless steel

Mehdi Haj, Hojjatollah Mansouri, Reza Vafaei, Golam Reza Ebrahimi, Ali Kanani

2013, 20(6): 529-534. doi: 10.1007/s12613-013-0761-0

中文摘要(334) PDF(15) SpringerLink

摘要:
The hot compression behavior of AISI 321 austenitic stainless steel was studied at the temperatures of 950–1100℃ and the strain rates of 0.01–1 s⁻¹ using a Baehr DIL-805 deformation dilatometer. The hot deformation equations and the relationship between hot deformation parameters were obtained. It is found that strain rate and deformation temperature significantly influence the flow stress behavior of the steel. The work hardening rate and the peak value of flow stress increase with the decrease of deformation temperature and the increase of strain rate. In addition, the activation energy of deformation (Q) is calculated as 433.343 kJ/mol. The microstructural evolution during deformation indicates that, at the temperature of 950℃ and the strain rate of 0.01 s⁻¹, small circle-like precipitates form along grain boundaries; but at the temperatures above 950℃, the dissolution of such precipitates occurs. Energy-dispersive X-ray analyses indicate that the precipitates are complex carbides of Cr, Fe, Mn, Ni, and Ti.

Warm/cold rolling processes for producing Fe-6.5wt% Si electrical steel with columnar grains

Hua-dong Fu, Zhi-hao Zhang, Hong-jiang Pan, Yuan-ke Mo, Jian-xin Xie

2013, 20(6): 535-540. doi: 10.1007/s12613-013-0762-z

中文摘要(242) PDF(15) SpringerLink

摘要:
A new technical prototype for producing Fe-6.5wt% Si electrical steel sheets by directional solidification, heat treatment before rolling, warm rolling, and cold rolling was proposed in the present study. The formability of Fe-6.5wt% Si electrical steel before rolling and the reasonable process parameters of this technical prototype were obtained. Experimental results reveal that the formability of Fe-6.5wt% Si electrical steel is improved significantly under the combination of directional solidification and heat treatment before rolling. Fe-6.5wt% Si electrical steel sheets with the thickness of 0.15 mm, bright surface, few edge cracks, and high rolling yield can be successfully fabricated using this technology without any intermediate annealing during the whole rolling. The combination of directional solidification, heat treatment before rolling, warm rolling, and cold rolling can work as a new process for highly efficient and compact fabrication of Fe-6.5wt% Si electrical steel sheets.

Microstructure and texture evolution of cold-rolled deep-drawing steel sheet during annealing

Le-yu Zhou, Lei Wu, Ya-zheng Liu, Xiao-jie Cheng, Jin-hong Sun

2013, 20(6): 541-548. doi: 10.1007/s12613-013-0763-y

中文摘要(289) PDF(13) SpringerLink

摘要:
In accordance with experimental results about the annealing microstructure and texture of cold-rolled deepdrawing sheet based on the compact strip production (CSP) process, a two-dimensional cellular automation simulation model, considering real space and time scale, was established to simulate recrystallization and grain growth during the actual batch annealing process. The simulation results show that pancaked grains form during recrystallization. {111} advantageous texture components become the main parts of the recrystallization texture. After grain growth, the pancaked grains coarsen gradually. The content of {111} advantageous texture components in the annealing texture increases from 55vol% to 65vol%; meanwhile, the contents of {112}〈110〉 and {100}〈110〉 texture components decrease by 4% and 8%, respectively, compared with the recrystallization texture. The simulation results of microstructure and texture evolution are also consistent with the experimental ones, proving the accuracy and usefulness of the model.

Processing effects on the magnetic and mechanical properties of FeCoNiAl_0.2Si_0.2 high entropy alloy

Ting-ting Zuo, Song-bo Ren, Peter K. Liaw, Yong Zhang

2013, 20(6): 549-555. doi: 10.1007/s12613-013-0764-x

中文摘要(319) PDF(17) SpringerLink

摘要:
High entropy alloys with the composition of FeCoNiAl_0.2Si_0.2 were prepared by arc melting and induction melting, denoted by A1 and A2, respectively. The samples prepared by these two techniques have a face-centered cubic (FCC) phase structure and a typical dendrite morphology. The tensile yield strength and maximum strength of A2 samples are about 280 and 632 MPa, respectively. Moreover, the elongation can reach 41.7%. These two alloys prepared by the different methods possess the similar magnetic properties. The saturation magnetization and coercivity can reach 1.151 T and 1400 A/m for Al samples and 1.015 T and 1431 A/m for A2 samples, respectively. Phases in A2 samples do not change, which are heat treated at different temperatures, then quenched in water. Only the sample, which is heat treated at 600℃ for 3 h and then furnace cooled, has a new phase precipitated. Besides, the coercivity decreases obviously at this temperature. Cold rolling and the subsequent heat treatment cannot improve the magnetic properties effectively. However, cold rolling plays an important role in improving the strength.

Effect of electric pulse on the crystal structure of solidified copper ingots

Li-hua Zhao, Li Zhan, Hao Bai, Da-qiang Cang

2013, 20(6): 556-562. doi: 10.1007/s12613-013-0765-9

中文摘要(281) PDF(9) SpringerLink

摘要:
To obtain advanced quality pure copper, the microstructure of solidified copper was optimized by imposing electric pulse on liquid copper in this study. Experiments were performed to determine the effect of electric pulse voltage, arrangement mode of electrodes, and energy input on the microstructure of solidified copper. The results show that, when the energy input of electric pulse is bigger than 28.95 kJ per ton copper, the percent of fine grains increases noticeably with the increase of energy input; but when the energy input of electric pulse is smaller than 28.95 kJ per ton copper, the percent of fine grains decreases with the increase of energy input. The influence order of above factors on grain refinement is electric pulse voltage > arrangement mode of electrodes > energy input. According to the above experimental results, the optimum process conditions are chosen as the voltage being 400 V and the energy input greater than 28.95 kJ per ton copper. Meanwhile, the best arrangement mode of electrodes should be that, one electrode is immerged in the middle of liquid copper in the crystallizer, and the other is connected to the inner wall of the crystallizer, which is divided into two electrode poles for the symmetrical electric field distribution.

Effects of phosphorus addition on the properties of Sn-9Zn lead-free solder alloy

Hui-zhen Huang, Xiu-qin Wei, Dun-qiang Tan, Lang Zhou

2013, 20(6): 563-567. doi: 10.1007/s12613-013-0766-8

中文摘要(284) PDF(9) SpringerLink

摘要:
This article explores the effects of phosphorus addition on the wettability between Sn-9Zn solder alloy and Cu substrates, the oxidation behavior and the corrosion behavior of Sn-9Zn solder alloy. Spreading test was used to characterize the wettability of Sn-9Zn-xP solder alloys to Cu substrates. The oxidation and corrosion behaviors of Sn-9Zn-xP solder alloys were determined by means of weight gaining, and secondary ion mass spectrometry was used to analyze the oxygen content. The role and mechanism of P in the solder alloys were also discussed. It is found that the addition of P can significantly improve the wettability of the solder alloys. Incorporating P into Sn-9Zn solder alloy obviously decreases the oxygen content and enhances the oxidation and corrosion resistance. Microstructure observations show that an appropriate amount of P can greatly refine coarse rod-like Zn-rich phases in Sn-9Zn solder alloy.

Influence of laser scanning speed on Cu-Zr-Al composite coatings on Mg alloys

Ya-li Gao, Meng Jie, Hai-bo Zhang

2013, 20(6): 568-573. doi: 10.1007/s12613-013-0767-7

中文摘要(237) PDF(8) SpringerLink

摘要:
To improve the surface properties of magnesium alloys, a study was conducted on Cu-Zr-Al composite coatings on AZ91HP magnesium alloy by laser cladding. The influence of laser scanning speed on the microstructures and properties of the coatings was discussed. The coatings consist of amorphous phase, Cu8Zr3, and Cu10Zr7. With the increase of laser scanning speed, the amorphous phase content of the coatings increases and reaches 60.56wt% with the laser scanning speed of 2.0 m/min. Because of the influence of laser scanning speed on the amorphous and crystal phases, the coatings show the maximum elastic modulus, hardness, and wear resistance at the laser scanning speed of 1.0 m/min. At the laser scanning speed of 2.0 m/min, the coatings have the best corrosion resistance.

Effect of modifying agents on the hydrophobicity and yield of zinc borate synthesized by zinc oxide

Nil Baran Acarali, Melek Bardakci, Nurcan Tugrul, Emek Moroydor Derun, Sabriye Piskin

2013, 20(6): 574-581. doi: 10.1007/s12613-013-0768-6

中文摘要(246) PDF(9) SpringerLink

摘要:
The aim of this study was to synthesize zinc borate using zinc oxide, reference boric acid, and reference zinc borate (reference ZB) as the seed, and to investigate the effects of modifying agents and reaction parameters on the hydrophobicity and yield, respectively. The reaction parameters include reaction time (1–5 h), reactant ratio (H₃BO₃/ZnO by mass: 2–5), seed ratio (seed crystal/(H₃BO₃+ZnO) by mass: 0–2wt%), reaction temperature (50–120℃), cooling temperature (10–80℃), and stirring rate (400–700 r/min); the modifying agents involve propylene glycol (PG, 0–6wt%), kerosene (1wt%–6wt%), and oleic acid (OA, 1wt%–6wt%) with solvents (isopropyl alcohol (IPA), ethanol, and methanol). The results of reaction yield obtained from either magnetically or mechanically stirred systems were compared. Zinc borate produced was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and contact angle tests to identify the hydrophobicity. In conclusion, zinc borate is synthesized successfully under the optimized reaction conditions, and the different modifying agents with various solvents affect the hydrophobicity of zinc borate.

Tensile and compressive behavior of Ti-based bulk metallic glass composites

Yong-sheng Wang, Guo-jian Hao, Jun-pin Lin

2013, 20(6): 582-588. doi: 10.1007/s12613-013-0769-5

中文摘要(215) PDF(7) SpringerLink

摘要:
This article focuses on the tensile and compressive characteristics of a Ti-based bulk metallic glass composite (BMGC). It is found that the yield stress, maximum strength, and fracture strain are 1380 MPa, 1516 MPa, and 4.3% for uniaxial tension, but 1580 MPa, 4010 MPa, and 29% for uniaxial compression, respectively. The composite displays a linear “work hardening” capacity under compression; however, the “work softening” behavior is observed in the true engineering stress-strain curve upon tensile loading. The fracture surfaces of specimens also exhibit dissimilar properties under the different loadings.

Effect of Nb on the corrosion behavior of continuous bulk metallic glass-coated steel wire composites

Xiao-hua Chen, Bao-yu Zhang, Xi-dong Hui

2013, 20(6): 589-592. doi: 10.1007/s12613-013-0770-z

中文摘要(237) PDF(6) SpringerLink

摘要:
(Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5)_100−xNb_x (at%, x=0 and 8) bulk metallic glasses (BMGs) were coated on the surface of Q195 steel wires by a continuous coating process. The potentiodynamic polarization tests of these BMGs were conducted in 3.5wt% NaCl aqueous solution. It is found that the addition of 8at% Nb into Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 alloy results in the improvement of corrosion resistance with the pitting potential of −52 mV, the open circuit potential of −446 mV, and the corrosion current density of 9.86×10⁻⁶ mA/cm². This may be attributed to that Nb is beneficial to passivate and stabilize Zr and Ti.

Preparation and photo-catalytic activity of TiO₂-coated medical stone-based porous ceramics

Ru-qin Gao, Xin-mei Hou

2013, 20(6): 593-597. doi: 10.1007/s12613-013-0771-y

中文摘要(328) PDF(7) SpringerLink

摘要:
Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO₂ thin films were loaded on the carrier by chemical liquid deposition method using titanium tetrachloride as a precursor. The micro-morphology and microstructure of the synthesized samples were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and mercury injection method. The photo-catalytic activity of the TiO₂ thin films was investigated by degrading formaldehyde. The main crystalline phase in the TiO₂ thin films calcined at 550℃ is anatase with the average particle size about 10 nm. The specific surface area of the carrier-coated nano-TiO₂ increases from 3.68 to 5.32 m²/g. The formaldehyde removal rate of the TiO₂/medical stone-based porous ceramics irradiated under an ultraviolet lamp for 120 min reaches 85.6%.

Comparative study of different membranes as separators for rechargeable lithium-ion batteries

Hong-yan Guan, Fang Lian, Yan Ren, Yan Wen, Xiao-rong Pan, Jia-lin Sun

2013, 20(6): 598-603. doi: 10.1007/s12613-013-0772-x

中文摘要(336) PDF(9) SpringerLink

摘要:
Membranes of polypropylene (PP), PP coated with nano-Al₂O₃, PP electrospun with polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), and trilayer laminates of polypropylene-polyethylene-polypropylene (PP/PE/PP) were comparatively studied. Their physical properties were characterized by means of thermal shrinkage test, liquid electrolyte uptake, and field emission scanning electron microscopy (FESEM). Results show that, for the different membranes as PP, PP coated with nano-Al₂O₃, PP electrospun with PVdF-HFP, and PP/PE/PP, the thermal shrinkages are 14%, 6%, 12.6%, and 13.3%, while the liquid electrolyte uptakes are 110%, 150%, 217%, and 129%, respectively. In addition, the effects on the performance of lithium-ion batteries (LiFePO₄ and LiNi_1/3Co_1/3Mn_1/3O₂ as the cathode material) were investigated by AC impedance and galvanostatic charge/discharge test. It is found that PP coated with Al₂O₃ and PP electrospun with PVdF-HFP can effectively increase the wettability between the cathode material and liquid electrolyte, and therefore reduce the charge transfer resistance, which improves the capacity retention and battery performance.

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2013年第20卷第6期