International Journal of Minerals, Metallurgy and Materials

姓名
邮箱
手机号码
标题
留言内容
验证码

Application and reliability analysis of DPM system in site investigation of HK weathered granite

Zhuoying Tan, Meifeng Cai, Zhongqi Yue, L. G. Tham, C. F. Lee

2005, 12(6): 481-488.

中文摘要(302) PDF(18) SpringerLink

摘要:
A drilling process monitor (DPM) for ground characterization of weathered granite is presented. The monitor is portable and can be mounted on a hydraulic rotary drilling rig to record various drilling parameters in real time during normal subsurface investigation. The identification method for dominative and subsidiary interfaces has been established. The study reveals that the monitored drilling parameters are dependent on geotechnical materials and can be further applied to characterize ground interfaces. The t-test between manual logging and DPM logging has been carried out. The results show that the DPM has high accuracy in interfaces detection and well agreement with the manual logging. The findings show that the device and data analysis method are of potential application in subsurface drilling exploration in weathered granites. It also seems to have prospective uses in the determination of orebody boundary as well as in the detection of geohazards.

Mineral

Quantitative analysis of biotechnical reinforcement for a steep slope consisting of composite coal-gangue-soil medium adjacent to a mined-out area

Xingping Lai, Mowen Xie, Fenhua Ren, Meifeng Cai

2005, 12(6): 489-494.

中文摘要(255) PDF(8) SpringerLink

摘要:
The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.

Mineral

3-D distribution of tensile stress in rock specimens for the Brazilian test

Yong Yu, Chunyan Meng

2005, 12(6): 495-499.

中文摘要(314) PDF(15) SpringerLink

摘要:
It is claimed that the formula used for calculating the tensile strength of a disk-shaped rock specimen in the Brazilian test is not accurate, because the formula is based on the 2-dimensional elastic theory and only suitable for very long or very short cylinders. The Matlab software was used to obtain the 2-dimensional distribution of stress in the rock specimen for Brazilian test. Then the 2-dimensional stress distribution in Brazilian disk was analyzed by the Marc FEM software. It can be found that the results obtained by the two software packages can verify each other. Finally, the 3-dimensional elastic stress in the specimen was calculated. The results demonstrate that the distribution of stress on the cross section of the specimen is similar to that in 2-dimension. However, the value of the stress on the cross section varies along the thickness of the specimen and the stress is bigger when getting closer to the end of the specimen. For the specimen with a height-to-diameter ratio of 1 and a Poisson’s ratio of 0.25, the tensile strength calculated with the classical 2-D formula is 23.3% smaller than the real strength. Therefore, the classical 2-D formula is too conservative.

Metallurgy

Dispersive bubble wall—a new method of flow control in tundish

Fuping Tang, Yanping Bao, Wei Jiang, Taiquan Li

2005, 12(6): 500-503.

中文摘要(646) PDF(7) SpringerLink

摘要:
Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall (DBW) is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW+weir on the flow pattern has been studied. The results show that this new structure of DBW+weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.

Metallurgy

Drag characteristics of power law fluids on an upstream moving surface

Liancun Zheng, Xinxin Zhang, Jicheng He

2005, 12(6): 504-506.

中文摘要(238) PDF(7) SpringerLink

摘要:
The specific problem to be considered here concerns the boundary layer problem of a non-Newtonian fluid on a flat plate in length, whose surface has a constant velocity opposite in the direction to that of the mainstream with U_W>>U_∞ or alternatively when the plate surface velocity is kept fixed but the stream speed is reduced to zero. A theoretical analysis for a boundary layer flow is made and the self-similar equation is determined. Solutions are presented numerically for special power index and the associated transfer behavior is discussed.

Materials

Effects of C and Mn elements on deformation-enhanced ferrite transformation in low carbon (Mn) steels

Rongfeng Zhou, Wangyue Yang, Rong Zhou, Zuqing Sun

2005, 12(6): 507-511.

中文摘要(246) PDF(12) SpringerLink

摘要:
Effects of C and Mn contents on the deformation-enhanced ferrite transformation (DEFT) in low carbon (Mn) steels have been investigated by hot compression. The microstructures of 2-4μm ultra-fine equiaxed ferrite grains with minors distributed homogeneously can be obtained by DEFT in all the tested steels. The more pronounced refinement is achieved as the C or Mn content increasing because of the higher-density nucleating sites and lower growth rate. The effectiveness of C on the level of refinement is more obvious than that of Mn.

Materials

Simulation of annealing process effect on texture evolution of deep-drawing sheet Stl5

Jinghong Sun, Yazheng Liu, Leyu Zhou

2005, 12(6): 512-516.

中文摘要(263) PDF(8) SpringerLink

摘要:
A two-dimensional cellular automaton method was used to simulate grain growth during the recrystallization annealing of deep-drawing sheet Stl5, taking the simulated result of recrystallization and the experimental result of the annealing texture of deepdrawing sheet St15 as the initial condition and reference. By means of computer simulation, the microstructures and textures of different periods of grain growth were predicted. It is achieved that the grain size, shape and texture become stable after the grain growth at a constant temperature of 700°C for 10 h, and the advantaged texture components {111 }<110> and {111 }<112> are dominant.

Materials

Carbides/nitrides precipitates in a C-Mn strip by CSP technology

Ling Zhang, Wangyue Yang, WeiweiZheng, Zuqing Sun

2005, 12(6): 517-520.

中文摘要(230) PDF(9) SpringerLink

摘要:
The carbides/nitrides precipitates in ferrite grains, on grain boundaries and dislocations were investigated on a hot-rolled C-Mn strip (0.16wt%C-1.22wt%Mn-0.022wt%Ti) produced by the CSP (compact strip production) technology using TEM and X-ray energy dispersive spectroscopy. The Pickering’s equation for the contribution of precipitates to the yield stress was also discussed. It is shown that there are numerous fine and dispersive precipitates TiC in the ferrite grains, on the grain boundaries and dislocations. Also there are a small amount of coarser Ti(C, N) particles and TiC particles associated with MnS. Precipitation strengthening on steels produced by the CSP technology is significant.

Materials

Influence of stress path change on the resistance to plastic deformation of cold rolled sheets

Zonghai Ding, Pavel Huml

2005, 12(6): 521-526.

中文摘要(241) PDF(8) SpringerLink

摘要:
Flat workpicces have been tested in order to investigate the influence of stress path change (loading mode) while keeping strain path unchanged. These investigations are pertinent to the testing of cold rolled strips and to subsequent forming. The workpieces which first compressed by plane strain compression in thickness direction were then tested in perpendicular direction in order to measure the influence of strain and stress path. The tension workpieces came from flat die compression test at different deformation histories. Two different materials were investigated: 18/8 Ti stainless steel and AW-1050 aluminium. The results show that the plastic flow by tension in lengthwise direction after pre-strain by compression in thickness direction will begin at an appreciably lower stress than that of the workpieces unloaded after pre-compression. Comparing with two materials, it can be seen that both 18/8 Ti stainless steel and AW-1050 aluminium behave similarly. The drop in yield stress is lower for AW-1050 aluminium than that for 18/8 Ti stainless steel. However, reloading in different directions than in the precious step results in significantly higher strain hardening.

Materials

Casting structure of pure aluminum by electric pulse modification at different superheated temperatures

Jingang Qi, Jianzhong Wang, Xingjiang Liu, Bing Wang, Daqiang Cang

2005, 12(6): 527-530.

中文摘要(204) PDF(7) SpringerLink

摘要:
Electric pulse modification (EPM) is a novel technique that reduces grain size by altering the structure of a melt. It was investigated that the response of the casting structure of high pure aluminum to EPM in different superheated melts. The results indicate that the grain refining effect of a given pulse electric field holds an optimal temperature range, moreover, a lower or higher superheated temperature will both disadvantage the improvements of casting structure. It essentially lies in the cooperative action between the distorted absorption of clusters and the activated capability of atoms in the aluminum melt.

Materials

XRD and TEM analysis of the microstructure in the brazing joint of 3003 cladding aluminum alloy

Tao Feng, Songnian Lou, Luhai Wu, Yajiang Li

2005, 12(6): 531-534.

中文摘要(304) PDF(20) SpringerLink

摘要:
The material used in this experiment was 3003 cladding aluminum alloy, the cladding metal was 4004 aluminum alloy. The aluminum plate was brazed by means of vacuum brazing. The microstructure in the brazing joint was studied by means of X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The test result indicates that the suitable brazing technique parameters are brazing temperature, 628°C; keeping time, 10 min; vacuum degree, 6.5×10^-4 Pa. XRD test indicates that there are new intermetallic compounds different from the base metal. TEM analysis indicates that Cu₂Mg and Cu₃Mn₂Mg are formed in the brazing joint. The shape of Cu₂Mg is irregular and the shape of Cu₃Mn₂Mg is circle, and there are tiny particles in it.

Materials

Strain rate sensitivity of tensile properties in high Nb containing TiAl alloys

Jianfeng Gao, Xiangjun Xu, Junpin Lin, Xiping Song, Yanli Wang, Guoliang Chen

2005, 12(6): 535-539.

中文摘要(261) PDF(9) SpringerLink

摘要:
The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.

Materials

Effect of RE on the ignition-proof, microstructure and properties of AZ91D magnesium alloy

Zhihong Chen, Xueping Ren, Ya Zhang

2005, 12(6): 540-544.

中文摘要(307) PDF(12) SpringerLink

摘要:
The magnesium alloy is prone to burn during die-casting, which limits its applications severely, so the effect of adding rare earth (RE) on the ignition-proof of AZ91D Mg alloy is studied. The results indicate that the addition of mischmetal RE elements has a remarkable influence on the ignition-proof property of the magnesium alloy. It is found that the ignition temperature of the magnesium alloy can be greatly raised by adding a proper amount of RE. When the amount is 0.1 wt%, the ignition temperature reaches 877°C which is 206°C higher than that of AZ91D without RE and the mechanical properties of the alloy are also improved. However, the amount of RE must be properly controlled because too much RE would induce grain coarsening and reduce the mechanical properties.

Materials

Corrosion behaviors of zinc and Zn-Ni alloy compositionally modulated multilayer coatings

Jingyin Fei, Guozheng Liang, Wenli Xin, Weikang Wang, Jianghong Liu

2005, 12(6): 545-552.

中文摘要(250) PDF(15) SpringerLink

摘要:
Zinc and Zn-Ni alloy compositionally modulated multilayer (CMM) coatings were electrodeposited from dual baths. The coated samples were evaluated in terms of surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The results obtained from the salt spray test show that the zinc and Zn-Ni alloy CMM coatings are more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy alone with a similar thickness. The corrosion potential measurement and anodic polarisation tests were undertaken to examine the probable corrosion mechanisms of zinc and Zn-Ni alloy CMM coatings. Analysis on the micrographic features of zinc and Zn-Ni alloy CMM coatings after the corrosion test explains the probable reasons why the Zn-Ni/Zn CMM coatings have a better protective performance. Surface morphologies and compositional analysis of the remaining coating material of Zn-Ni alloy deposit after the corrosion test confirms the dezincification mechanism of the Zn-Ni alloy deposit during the corrosion process.

Materials

Effects of temperature and concentration of sulfuric acid on the electrodeposition of grainy electrolytic manganese dioxide

Huajun Guo, Xinhai Li, Luping Liu, Xinming Zhang, Zhixing Wang, Wenjie Peng, Bingquan Zhu

2005, 12(6): 553-557.

中文摘要(357) PDF(15) SpringerLink

摘要:
The effects of temperature and the concentration of sulfuric acid on the cell voltage, the anode current efficiency of electrodeposition and the particle size of grainy electrolytic manganese dioxide (EMD) were investigated. The structure, particle size and appearance of grainy EMD were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrograph measurements. As the concentration of sulfuric acid increases, both the cell voltage and the average anode current efficiency decrease. With the increase of electrolysis temperature in the range of 30-60°C, the cell voltage, average anode current efficiency and particle size decrease. The optimum temperature of 30°C and concentration of sulfuric acid of 2.5 mol/L for electrodeposition of the grainy EMD were obtained. XRD patterns show that the grainy EMD electrodeposited under the optimum conditions consists of γ-MnO₂ and has an orthorhombic lattice structure. According to the results of SEM, the grainy EMD has a spherical or sphere-like appearance and a narrow particle size distribution with an average size of about 7 μm. The grainy EMD is a promising cathode of rechargeable alkaline batteries for high energy density and a prospective precursor for production of the LiMn₂O₄ cathode of lithium ion batteries.

Materials

Atomic force microscope study of WC-10Co cemented carbide sintered from nanocrystalline composite powders

Xiaoliang Shi, Gangqin Shao, Xinglong Duan, Runzhang Yuan

2005, 12(6): 558-563.

中文摘要(256) PDF(11) SpringerLink

摘要:
In order to compare the spark plasma sintering (SPS) process plus hot isostatic press (HIP) with vacuum sintering plus HIP, an investigation was carried out on the topography, microstructure and gain size distribution of nanocrystalline WC-l0Co composite powder and the sintered specimens prepared by SPS plus HIP and by vacuum sintering plus HIP by means of atomic force microscopy (AFM). The mechanical properties of the sintered specimens were also investigated. It is very easy to find cobalt lakes in the specimen prepared by vacuum sintering plus HIP process. But the microstructure of the specimen prepared by SPS plus HIP is more homogeneous, and the grain size is smaller than that prepared by vacuum sintering plus HIP. The WC-10Co ultrafine cemented carbide consolidated by SPS plus HIP can reach a relative density of 99.4%, and the transverse rupture strength (TRS) is higher than 3540 MPa, the Rockwell A hardness (HRA) is higher than 92.8, the average grain size is smaller than 300 nm, and the WC-10Co ultrafine cemented carbide with excellent properties is achieved. The specimen prepared by SPS with HIP has better properties and microstructure than that prepared by vacuum sintering with HIP.

Materials

Formation of macroporous gel morphology by phase separation in the silica sol-gel system containing nonionic surfactant

Junsheng Wu, Xiaogang Li, Wei Du, Hua Chen

2005, 12(6): 564-571.

中文摘要(246) PDF(11) SpringerLink

摘要:
The phase separation and gel formation behavior in an alkoxy-derived silica sol-gel system containing C₁₆EO₁₅ has been investigated. Various gel morphologies similar to other sol-gel systems containing organic additives were obtained by changing the preparation conditions. Micrometer-range interconnected porous gels were obtained by freezing transitional structures of phase separation in the sol-gel process. The dependence of the resulting gel morphology on several important reaction parameters such as the starting composition, reaction temperature and acid catalyst concentration was studied in detail. The experimental results indicate that the gel morphology is mainly determined by the time relation between the onset of phase separation and gel formation.

Materials

Bonding strength of graded anti-corrosive coatings of fluoroethylenepropylene (FEP)/polyphenylene sulfide (PPS)

Jie Bian, Weiqiang Wang, Congsheng Guan, Yonghui Zhao

2005, 12(6): 572-576.

中文摘要(261) PDF(9) SpringerLink

摘要:
Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis (EPMA) verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.

留言板

2005年第12卷第6期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

留言板

2005年 第12卷 第6期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

2005年第12卷第6期