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2005年  第12卷  第5期

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Mineral
Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates
Yuqun Meng
2005, 12(5): 385-389.
中文摘要(269) PDF(10) SpringerLink
摘要:
A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching (FGLAL), enhanced agitation alkali-leaching (EAAL), thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arsenides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.
Metallurgy
A mathematical model for optimized operation and control in a CDQ-Boiler system
De Wang, Too Yang, Zhi Wen, Junxiao Feng, Ning Kong, Qin Wang, Weimin Wang
2005, 12(5): 390-393.
中文摘要(325) PDF(18) SpringerLink
摘要:
Based on analyzing the thermal process of a CDQ (coke dry quenching)-Boiler system, the mathematical model for optimized operation and control in the CDQ-Boiler system was developed. It includes a mathematical model for heat transferring process in the CDQ unit, a mathematical model for heat transferring process in the boiler and a combustion model for circulating gas in the CDQ-Boiler system. The model was verified by field data, then a series of simulations under several typical operating conditions of CDQ-Boiler were carried on, and in turn, the online relation formulas between the productivity and the optimal circulating gas, and the one between the productivity and the optimal second air, were achieved respectively. These relation equations have been successfully used in a CDQ-Boiler computer control system in the Baosteel, to realize online optimized guide and control, and meanwhile high efficiency in the CDQ-Boiler system has been achieved.
Metallurgy
Effects of oxygen potential and flux composition on dephosphorization and rephosphorization of molten steel
Zhihong Tian, Junpu Jiang, Kaike Cai, Xinhua Wang, Lixin Zhu, Xiaodong Yin, Hongzhi Shi
2005, 12(5): 394-399.
中文摘要(234) PDF(15) SpringerLink
摘要:
The dephosphorization experiments of low phosphorus containing steel by CaO-based and BaO-based fluxes were carried out. The effects of the oxygen potential in molten steel and the BaO content in the slag on dephosphorization and rephosphorization of molten steel were analyzed. The results showed that the dephosphorization ratio of more than 50% and the ultra-low phosphorus content of less than 0.005% in steel were obtained by the three kinds of dephosphorization fluxes as the oxygen potential of molten steel higher than 400×10-6. Rephosphorization of molten steel was serious as the oxygen content of molten steel lower than 10×10-6. BaO-based fluxes can improve the dephosphorization effect and reduce the phosphorus pick-up effectively under the condition of weak deoxidization of molten steel (the oxygen potential is about 100×10-6), but can not prevent rephosphorization under the condition of deep deoxidization of molten steel (the oxygen potential less than 10×10-6).
Metallurgy
Mathematical model of solidification for round CC billets
Yonglin Li, Pei Zhao, Guoguang Cheng, Shengtao Qiu, Jianping Zhang
2005, 12(5): 400-405.
中文摘要(250) PDF(12) SpringerLink
摘要:
A coupled mathematical model was established to simulate the whole solidification process of round billet continuous casting for wheel steel using piecewise linear functions of heat flux density in the mold, the secondary cooling zone and the with-drawing-straightening zone. The calculated results were consistent with the measured data showing that the model accords with the practice. The surface temperature and the solidified shell thickness of round billets are more strongly influenced by casting speed than by casting temperature. The holding zones have effect on surface temperature, which is more obvious for the 450 mm round billet. The relation between casting temperature/speed and solidification end is expressed as a linear function. The solidification end is located after straightening machine.
Materials
Subgrains and boron distribution of low carbon bainitic steels
Xuemin Wang, Bing Cao, Chengjia Shang, Xueyi Liu, Xinlai He
2005, 12(5): 406-409.
中文摘要(362) PDF(10) SpringerLink
摘要:
The structure variation of deformed austenite during the relaxation stage after deformation at various temperatures in an Nb-B ultra low carbon bainitic steel and Fe-Ni alloy was studied by the thermo-simulation. Optical microscope and TEM were applied to analyze the microstructure after RPC (Relaxation-precipitation-controlling phase transformation technique) and the evolution of dislocation configuration. The particle tracking autoradiography (PTA) technique, revealing the distribution of boron, was employed to show the change of boron segregation after different relaxation times. The results indicate that during the relaxation stage the recovery occurs in the deformed austenite, the dislocations rearrange and subgrains form. During the subsequent cooling the boron will segregate at the boundaries of subgrains.
Materials
Quantitative analysis of Ni effect on CCT diagrams of novel air-cooled bainite steels using artificial neural network models
Weihong Xu, Wei You, Yaxiu Liu, Bingzhe Bai, Hongsheng Fang
2005, 12(5): 410-415.
中文摘要(247) PDF(11) SpringerLink
摘要:
The quantitative effect of Ni content on continuous cooling transformation (CCT) diagrams of novel air-cooled bainite steels was analyzed using artificial neural network models. The results showed that Ni may retard the high- and medium-temperature transformation and martensite transformation. The results conform to the materials science theories.
Materials
Modeling of hydrogen diffusion process at a blunt notch in zirconium
Xingqiao Ma, Sanqiang Shi, Senyang Hu, Chungho Woo, Longqing Chen
2005, 12(5): 416-421.
中文摘要(314) PDF(11) SpringerLink
摘要:
The two-dimensional diffusion of interstitial hydrogen atoms in zirconium in a non-uniform stress field was simulated using the phase-field method. The interaction between hydrogen interstitials and the stress field was described by Khachaturyan’s elastic theory. The Cahn-Hilliard diffusion equation was then solved by an explicit finite difference method. The result shows that hydrogen atoms diffuse to the high-tensile hydrostatic region near the tip of the notch. The content of hydrogen near the tip of the notch increases by 13%, while the stress distribution caused by hydrogen interstitials around the notch is modified by only 0.7%.
Materials
Tensile behavior of AA3104 aluminum sheets at low deformation degree
Quancang Ma, Weimin Mao, Huiping Feng
2005, 12(5): 422-426.
中文摘要(287) PDF(14) SpringerLink
摘要:
The texture of a rolled AA3104 aluminum sheet was measured by the X-ray transmission method. The Lankford values or r values (ratio of plastic strain) and yield strengths in directions of 0, 15, 30, 45, 60, 75, and 90° to RD (rolling direction) of the sheet were tested during tensile loading at a strain of 2%. r values were predicted by the Sachs model and the reaction stress model in consideration of the measured texture. The simulated results indicate that r values calculated by the Sachs model are more exactly approaching with the experimental values on the whole than those predicted by the reaction stress model. The deformation behavior of the AA3104 aluminum sheet reveals characteristic predicted by the Sachs model, which should be resulted from the sheet geometry different from bulk material as well as the low tensile deformation degree.
Materials
Fabrication of metal/metal functionally graded materials with a high melting point difference
Zhangjian Zhou, Changchun Ge
2005, 12(5): 427-430.
中文摘要(308) PDF(13) SpringerLink
摘要:
Three kinds of full compositional distribution (from 0 to 100wt%W) W/Cu FGMs (functionally graded materials) with high density is fabricated by resistance sintering under ultra-high pressure. Microstructure analysis showed that the good grading composition of all FGMs has been obtained. The sintering mechanism of W is mainly solid state sintering. Thermal shock test in air demonstrated that the grading at the interface between W and Cu is effective for the reduction of thermal stress, but obvious transverse and vertical cracks occur in the pure W layer. The oxidation of the W60Cu40 layer and the W40Cu60 layer is heavier than that of the other layers.
Materials
Effect of the formation process of transient liquid phase (TLP) on the interface structure of TiAl joints
Huiping Duan, Jun Luo, Karl-Heinz Bohm, Mustafa Koçak
2005, 12(5): 431-435.
中文摘要(279) PDF(12) SpringerLink
摘要:
TiAl has been joined employing the transient liquid phase (TLP) bonding with Ti combined with Cu, Ni or Fe foils. Experimental results showed that though the interface structures of the joints are quite different, all the joined zones are composed of five sublayers, i.e. two diffusion zones, two interfacial zones and an interlayer. It has been convinced that the formation process of the transient liquid phase controls the diffusion behavior of melting point depressant (MPD) Cu, Ni, and Fe atoms, which leads to form different interface structures of the joints.
Materials
Investigation on laser cladding of MoSi2 powder on steel
Laiqi Zhang, Guangnan Chen, Zuqing Sun
2005, 12(5): 436-439.
中文摘要(302) PDF(13) SpringerLink
摘要:
The feasibility of the fabrication of coatings for elevated-temperature structural applications by laser cladding MoSi2 powder on steel was investigated. A dense and crack-free fine coating, well-bonded with the substrate has been obtained by this technique. This coating consists of FeMoSi, Fe2Si and a small amount of Mo5Si3 due to dilution of the substrate in the coating. The microstructure of the coating is characterized of typical fine dendrites. The dendrites are composed of FeMoSi primary phase, and the interdendritic areas are two eutectic phases of FeMoSi and Fe2Si. The hardness of the coating reaches 845 Hv0.5, 3.7 times larger than that of the steel substrate (180 Hv0.5).
Materials
Method of temperature rising velocity and threshold control of electron beam brazing
Xuedong Wang, Shun Yao
2005, 12(5): 440-444.
中文摘要(213) PDF(10) SpringerLink
摘要:
In order to accommodate electron beam to the brazing of the joints with various curve shapes and the brazing of thermo sensitive materials, the method of electron beam scanning and brazing temperature control was developed, in which electron beam was controlled to scan according to predefined scanning track, and the actual temperature rising velocity of the brazed seam was limited in an allowed scope by detecting the brazed seam temperature, calculating the temperature rising velocity and adjusting the beam current during the brazing process; in addition, through the setting of the highest allowed temperature, the actual temperature of the brazed seam could be controlled not exceeding the threshold set value, and these two methods could be employed alone or jointly. It is shown that high precision temperature control in electron beam brazing could be realized and the productivity be increased by the proposed method.
Materials
Reactive diffusion bonding of SiCp/Al composites by insert layers of mixed Al-Si and Al-Si-SiC powders
Jihua Huang, Yueling Dong, Yun Wan, Jiangang Zhang, Hua Zhang
2005, 12(5): 445-449.
中文摘要(287) PDF(12) SpringerLink
摘要:
Mixed Al-Si and Al-Si-SiC powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC (metal matrix composites). The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructure. Using the mixed Al-Si-SiC powder as the insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer, which results in the bad shear strength of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si-SiC powder, even lower than that of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si powder. Ti and Mg added in the insert layers obviously improve the strength of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si-SiC powder, especially, Mg has a more obvious effect.
Materials
Abrasive wear behaviors of high velocity arc sprayed iron aluminum composite coatings
Weipu Xu, Binshi Xu, Wei Zhang, Zixin Zhu, Yixiong Wu
2005, 12(5): 450-454.
中文摘要(280) PDF(9) SpringerLink
摘要:
The High Velocity Arc Spraying (HVAS) technology was used to prepare Fe-Al composite coatings by the adding of different elements into cored wires to obtain different Fe-Al coatings. The added compounds do great effect on the properties of the composite coatings. The microstructures and abrasive wear performances of the coatings were assessed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and THT07-135 high temperature wear equipment. It was found that the adding of Cr3C2 can greatly increase the room temperature wear behavior, and Fe-Al/WC coatings have adapting periods at the beginning of wear experiment. With the rise of temperature, the wear resistance of Fe-Al/Cr3C2 coatings becomes bad from room temperature to 250°C, and then stable from 250°C to 550°C; the wear resistance of Fe-Al/WC becomes well with the rise of temperature. The adding of Cr and Ni can also improve wear performances of Fe-Al composite coatings.
Materials
Surface composites fabricated by vacuum infiltration casting technique
Guirong Yang, Yuan Hao, Wenming Song, Jinjun Lü, Ying Ma
2005, 12(5): 455-459.
中文摘要(312) PDF(16) SpringerLink
摘要:
Alumina (Al2O3) particles reinforced copper matrix surface composites were fabricated on the bronze substrate using the vacuum infiltration casting technique. Three cases were obtained in the vacuum infiltration casting technique: no infiltration, partial infiltration and full infiltration (the thickness of preforms do not exceed 3.5 mm). The reason of no infiltration is that the vacuum degree is not enough so that the force acting on the liquid metal is lower than the resistance due to the surface tension. Partial infiltration is because of somewhat lower vacuum degree and pouring temperature. Full desired infiltration is on account of suitable infiltration casting conditions, such as vacuum degree, pouring temperature, grain size and preheating temperature of the preform. The most important factor of affecting formation of surface composites is the vacuum degree, then pouring temperature and particle size. The infiltration mechanism was discussed on the bases of different processing conditions. The surface composite up to 3.5 mm in thickness with uniformly distributed Al2O3 particles could be fabricated via the vacuum infiltration casting technique.
Materials
Processing and characterization of Cf/SiC composites
Xinbo He, Bin Ye, Xuanhui Qu, Changrui Zhang, Xingui Zhou
2005, 12(5): 460-463.
中文摘要(262) PDF(11) SpringerLink
摘要:
Carbon fiber-reinforced SiC composites were prepared by precursor pyrolysis-hot pressing (PP-HP) and precursor impregnation-pyrolysis (PIP), respectively. The effect of fabrication methods on the microstructure and mechanical properties of the composites was investigated. It was found that the composite prepared by PP-HP exhibits a brittle fracture behavior, which is mainly ascribed to a strongly bonded fiber/matrix interface and the degradation of the fibers caused by a higher processing temperature. On the contrary, the composite prepared by PIP shows a tough fracture behavior, which could be rationalized on the basis of a weakly bonded fiber/matrix interface as well as a higher strength retention of the fibers. As a result, in comparison with the composite prepared by PP-HP, the composite prepared by PIP achieves better mechanical properties with a flexural strength of 573.4 MPa and a fracture toughness of 17.2 MPa·m1/2.
Materials
Cementing properties of steel slag activated by sodium silicates and sodium hydroxide
Wen Ni, En Wang, Jianping Li, Han Sun
2005, 12(5): 464-468.
中文摘要(315) PDF(15) SpringerLink
摘要:
Steel slag which is mainly composed of γ-Ca2SiO4 and other silicates or alumino-silicates is activated by sodium silicates and sodium hydroxide. The powders of such steel slag are usually inert to hydrate and subsequently have very low ability of cementing. But when sodium silicates and sodium hydroxide are used as activators the steel slag shows very good properties of cementing. When activated with NaOH solution the hardened slurry of the steel slag has a compressive strength of 11.13 MPa after being cured for 28 days. When activated with Na2SiO3 solution the samples after being cured for 28 days have an average compressive strength of 40.23 MPa. While the steel slag slurry which is only mixed with water has a compressive of 0.88 MPa after being cured for 28 days.
Materials
Resistance to chemical attack of bittern-resisting cement in high-bittern environment
Yunbing Hou, Bingwen Wang, Yu Chen, Botao Zhang, Lin Yu
2005, 12(5): 469-475.
中文摘要(250) PDF(9) SpringerLink
摘要:
A new kind of bittern-resisting cement (BRC) was introduced. This material is based on the ternary cementitious system of clinker containing C4A3 S phase, high-activity ground granulated blast-furnace slag (GGBFS) and fly ash (FA). The hydration process and the hydrated products of BRC were studied by means of XRD, TG-DTA and SEM, and the resistance to chemical attack of BRC in high-bittern environment was also examined. The corrosion experiment in seven kinds of brines proved that BRC exhibits an excellent resistance to chemical attack of bittern. The corrosion resistance factors were calculated and all of them were greater than 0.96. It showed that BRC totally controls the cement-based material corrosion in brines from four aspects: (1) making full use of the dominant complementation effect of mineral materials; (2) diminishing the hydrated products easy to be attacked; (3) improving the microstructure of hardened cement mortar; (4) degrading the chemical attack of bittern.
Materials
An experimental study of temperature and moisture content of wet porous materials under short-pulsed laser heating
Renxi Jin, Xiulan Huai
2005, 12(5): 476-480.
中文摘要(208) PDF(9) SpringerLink
摘要:
The measurements of temperature and moisture content of a wet porous material were accomplished on the micro-seconds scale. The temperature wave was observed when the wet porous material was heated by short-pulsed laser with high power. It firstly revealed that the moisture content of wet porous material rapidly rises twice in one laser irradiation. The influences of laser parameters, the thickness and initial moisture content of the wet porous material on its temperature and moisture content were investigated.

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