International Journal of Minerals, Metallurgy and Materials

姓名
邮箱
手机号码
标题
留言内容
验证码

Prediction of Rock Burst with Deep Mining Excavation in Linglong Gold Mine

Meifeng Cai, Jinan Wang, Shuanghong Wang

2001, 8(4): 241-243.

中文摘要(299) PDF(25) SpringerLink

摘要:
To predict rock burst in deep mining excavation in Linglong gold mine, systematical laboratory tests of mechanical properties of rock, in situ stress measurement and 3-D FEM analysis on energy distribution in rock mass surrounding deep mining rooms were carried out. According to various prediction criteria of rock burst, it is concluded that rock burst is liable to occur during deep mining excavation in the mine.

Mineral

Recovery of Level Pillar between Open-pit and Underground Mine by Using Underhand Heading Fill Method

Sijing Cai, Hai Zhao, Shangjun Ying

2001, 8(4): 244-247.

中文摘要(177) PDF(10) SpringerLink

摘要:
The upper part of the Fujia deposit was mined out by open-pit, and the lower part is being mined underground. The level pillar between open-pit and underground mine had a thickness of 24 m, a length of 300 m and a maximum width of 35 m. As the level pillar contained about 5.2 million ton ore of high nickel grade, it was necessary to recover the level pillar. Because of special need of safety, underhand heading cut-and-fill stoping method was used. For the first two layers of heading, the cemented fill materials were a mix of water and high-aluminum-content cement with silicate gelling agent; and for other heading layers, total tailings was added into the fill mix in order to reduce the cement consumption. Finally, the level pillar was recovered successfully.

Metallurgy

Calculation Models of Mass Action Concentrations for Metallic Melts Involving Monotectic

Jian Zhang

2001, 8(4): 248-253.

中文摘要(168) PDF(8) SpringerLink

摘要:
Based on the phase diagrams, measured activities as well as△G^m and △G^xs, calculating models of mass action concentrations for metallic melts involving monotectic have been formulated. The calculated results agree with practice on the whole, showing that the models deduced generally can reflect the structural characteristics of these melts. The metastable compounds formed in the melts are of the types A₂B₃, AB₂, A₂B₃ or AB and A₂B₃+AB etc..

Metallurgy

3-D Finite-Element Numerical Simulation of Centrifugal Induction Electrosalg Casting Solidification Process

Xichun Chen, Deguang Zhou, Jie Fu, Weiguo Xu

2001, 8(4): 254-258.

中文摘要(170) PDF(7) SpringerLink

摘要:
A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The results showed that the good agreement was obtained between the numerical simulation and the experiments. Based on the numerical simulation results, the characteristics of temperature distribution in the castings during CIESC solidification process were analyzed and summarized. According to the G/R^1/2 method and numerical simulation results, there is no any shrinkage defect in the CIESC casting and structure or casting is fine and compact.

Metallurgy

A Mathematical Model on Vacuum Chamber of a Multifunctional RH-degasser

Yisheng Chen, Youduo He, Daqiang Cang, Zongze Huang

2001, 8(4): 259-263.

中文摘要(215) PDF(15) SpringerLink

摘要:
A 3D-mathematical model was developed for the simulation of gas flow, combustion and heat convection in RH vacuum chamber. Under different conditions, the influences of the Kawasaki Oxygen Top Blowing system (KTB) on the gas flow, chemical reactions and temperature distributions were calculated based on the model. The optimum position of the lance is suggested for the RH-KTB degassing process.

Metallurgy

Extra Low NO_x Emission Furnace with HTAC Technology

Yunze Guan, Daqiang Cang, Xiongfang Nie, Hao Bai, Xianzhao Zhang

2001, 8(4): 264-266.

中文摘要(209) PDF(9) SpringerLink

摘要:
HTAC (High Temperature Air Combustion) technology needs high temperature air and low oxygen atmosphere to complete its unique combustion and achieve extra low NO_x production. In order to apply HTAC technology to forge furnace and meet the NO_x emission standard, exhaust gas regeneration technology in combination with no-fuel-switch and U-shape air circulation methods was applied on forge furnace. The results show that extra low NO_x emission (NO_x = 2.9 × 10^-5, in volume fraction) could be obtained, the NO, emission meets the standards of Japan and US, HTAC mechanism is discussed finally.

Materials

Thermoelectric Properties of N-typer Bi₂Te₃-PbTe Graded Thermoelectric Materials with Different Barriers

Guiying Xu, Changchun Ge, Yanping Gao, Weiping Shen

2001, 8(4): 267-269.

中文摘要(202) PDF(8) SpringerLink

摘要:
In order to investigate the adaptability of thermoelectric materials system with different barriers to functional graded thermoelectric materials, n-type Bi₂Te₃ and PbTe two segments graded thermoelectric materials (GTM) with different barriers were fabricated by conventional hot pressing method. Metals Cu, Al, Fe, Co and Ni were used as barriers between two segments. The effects of different barriers on thermoelectric properties of GTM were investigated. The phase and crystal structures were determined by x-ray diffraction analysis (XRD). The distributions of different compositions were analyzed by electron microprobe analysis (EMA). The thermoelectric properties were measured at 303 K along the direction parallel to the pressing direction. The electric conductivity of samples was measured at 303 K by the four-probe technique. To measure the Seebeck coefficient, heat was applied to the samples, which were placed between two Cu discs. The thermoelectric electromotive force (E) was measured upon applying small temperature differences (△T<275 K) between the both ends of the samples. The Seebeck coefficient of the samples was determined from the E/△T.

Materials

XPS Studies of Chemical States of NiO/NiFe Interface

Guanghua Yu, Chunlin Chai, Fengwu Zhu, Jimei Xiao, Wuyan Lai

2001, 8(4): 270-273.

中文摘要(244) PDF(19) SpringerLink

摘要:
Ta/NTiO/NiFe/Ta multilayers were prepared by radio frequency reactive and dc magnetron sputtering. The exchange coupling field between NiO and NiFe reached 9.6 × 10³ A/m. The compositions and chemical states at the interface region of NiO/NiFe were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique, The results show that there are two thermodynamically favorable reactions at NiO/NiFe interface: NiO+Fe = Ni + FeO and 3NiO+2Fe =3 Ni+Fe₂O₃. The thickness of the chemical reaction area estimated by angle-resolved XPS was about 1-1.5 nm. These interface reaction products appear magnetic defects, and the exchange coupling field H_ex and the coereivity H_c of NiO/NiFe are affected by these defects.

Materials

Effect of Preparation Condition on Low-density PS Particle Size and Distribution

Huili Fan, Jiemin Liu, Meijuan Wen, Weixue Tian

2001, 8(4): 274-276.

中文摘要(218) PDF(11) SpringerLink

摘要:
The preparation conditions were studied in order to obtain smaller, narrow size-distributed and low-density polystyrene (PS) micro-particles by suspension polymerization. The results show that some of preparation conditions, the shape and position of stirrers, and stirring rate etc., have important influence on the size and distribution of particles. The preparation conditions must be carefully designed and controlled in order to obtain high-quality PS beads. A bow-shaped stirrer is helpful to produce small-sized particles and narrow size distribution, and the upper edge of a stirrer should be set to the same level as the surface of mixture, and the stirring rate should be controlled in the range of 520-600 r/min.

Materials

Modal Analysis of Thread off Failure of Oil Round Thread Casing Connection

LiWang, Yong Zang, Zhaoneng Chen, Dechun Tong, Jiaxiang Zou

2001, 8(4): 277-279.

中文摘要(152) PDF(10) SpringerLink

摘要:
The dynamic modal model analysis of the oil casing connection is done by finite element method (FEM), and the first nature frequency, the second nature frequency, the vibration mode shape and the time domain of the node displacement and the element stress variation in the thread connection are gotten. The Von.Mises stresses of the connection in the static and dynamic state are also studied. The results of calculation and analysis show: (1) because the maximum of static stress is at the coupling thread end of connection, the connection begins to thread off at the coupling thread end, which is in accord with the results of the thread off experiment in laboratory; (2) because the first nature frequency is very high, the probability of casing connection to be damaged from vibration is little; (3) the shock dynamic load makes casing connection begin to thread off at the tube thread end.

Materials

A Research on the Joining of SiC Composite to 40 Cr Steel

Chengchang Jia, Jianxin Chu, Qingshan Zhao

2001, 8(4): 280-282.

中文摘要(204) PDF(8) SpringerLink

摘要:
SiC composites and 40 Cr Steels were joined with Ag-Cu-Ti solder in order to develop a new method of joining ceramics to metal. Effects of solder component and process parameters on the joining strength were investigated. The results show that some chemical reactions occur on the jointing interface between ceramics and metal. Higher joining strength is achieved when titanium is 0.2% (mass fraction) in the solder. The thickness of solder also affects the joining characteristics, and 0.2-0.3 mm thickness of solder is the most suitable.

Materials

Study on Bonding of Steel-mushy Al-7graphite

Peng Zhang, Yunhui Du, Daben Zeng

2001, 8(4): 283-285.

中文摘要(151) PDF(7) SpringerLink

摘要:
The bonding of steel-mushy Al-7graphite was studied. The relationship between interfacial shear strength of bonding plate and solid fraction of Al-7graphite mushy was obtained, and the interfacial structure of bonding plate was determined. The results showed that: under the condition of 500 ℃ for preheat temperature of steel plate and 10 mm/s for rolling speed, the largest interfacial shear strength of bonding plate was 70.1 MPa when solid fraction of Al-7graphite mushy was 34.6%.

Materials

SEM In-situ Observation at Tensile Loading on Surface Inclusion in PM Rene95 Superalloy

Xiao Li, Lina Zhang, Jianxin Dong, Maicang Zhang, Yaohe Hu, Xishan Xie

2001, 8(4): 286-289.

中文摘要(168) PDF(14) SpringerLink

摘要:
The observation on crack initiation and propagation of surface inclusion Al₂O₃ in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix interface vertical to the applied stress direction, and easily propagate along the interface into the matrix. The interface of inclusion/matrix is just mechanically bounded on the base of SEM observation. The weak bonding of inclusion/matrix interface and stress concentration around inclusions are the main reasons of the matrix/inclusion interface debonding and local plastic deformation under the tensile loading in the in-situ tension test. Surface inclusion does not definitely lead to the failure of in-situ tension test. But the early surface crack initiation caused by ceramic inclusion is critically harmful to the LCF property of PM Rene95 superalloy, which can't be ignored.

Materials

Mechanism of High Temperature Deformation in Cast Ti46Al8.5Nb0.2W Alloy

Zicheng Liu, Junpin Lin, Yanli Wang, Zhi Lin, Guoliang Chen

2001, 8(4): 290-294.

中文摘要(184) PDF(8) SpringerLink

摘要:
Compression tests A ere conducted in the two phase Ti46Al8.5Nb0.2W alloy with a cast microstructure under the strain rates ranging from 2×10^-5 s^-1 to 10^-2 s^-1 at temperatures ranging front 900℃ to 1100℃. It was found that there exist approximately linear relationships between the flow stress and the logarithm of strain rate at different temperatures. The strain rate dependence was analzed by the thermal activation theory and dislocation climbing is regarded as the controlling mechanism during high temperature compression tests.

Materials

Molecular Dynamics Simulation of Dealloyed Layer-induced Tensile Stress in Cu₃Au

Qikai L, Yue Zhang, Mark Hoffman, Wuyang Chu

2001, 8(4): 295-298.

中文摘要(173) PDF(12) SpringerLink

摘要:
During stress corrosion cracking of Cu₃Au alloy, there is a dealloyed layer on its surface because of preferential dissolution of Cu, and there is a linear distribution of Cu vacancy concentration in the dealloyed layer. Molecular dynamics simulation has been done on the three-dimensional crystal (about 148 000 atoms) by employing the embedded-atom method (EAM) potential. Simulation shows that Cu₃Au crystal in which there is a dealloyed layer on one surface and one end is fixed will be deflected after relaxing for a long time because of a tensile stress generated at or near the dealloyed layer interface. The deflection and then the tensile stress increase with increasing the depth of dealloyed layer and the vacancy concentration in the dealloyed layer.

Information

Synchronization of Digital Chaos in Secure Communication Systems

Geng Zhao, Deling Zheng, Shaojun Huang

2001, 8(4): 299-305.

中文摘要(220) PDF(6) SpringerLink

摘要:
The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

Information

Improve Fractal Compression Encoding Speed Using Feature Extraction and Self-organization Network

Berthe Kya, Yang Yang

2001, 8(4): 306-310.

中文摘要(212) PDF(8) SpringerLink

摘要:
Image compression consists of two main parts: encoding and decoding. One of the important problems of the fractal theory is the long encoding implementation time, which hindered the acceptance of fractal image compression as a practical method. The long encoding time results from the need to perform a large number of domain-range matches, the total encoding time is the product of the number of matches and the time to perform each match. In order to improve encoding speed, a hybrid method combining features extraction and self-organization network has been provided, which is based on the feature extraction approach the comparison pixels by pixels between the feature of range blocks and domains blocks. The efficiency of the new method was been proved by examples.

Information

Research on Vibration Properties of the Drill-punch Mechanism for Taphole Drill

Jianping Liu, Yongfang Liao

2001, 8(4): 311-313.

中文摘要(200) PDF(7) SpringerLink

摘要:
A new type taphole drill was designed. The vibration properties of them drill-punch mechanism for the new type taphole drill were researched, the laws of its inherent characteristics were found. The measures to add punch amplitude and to reduce traverse vibration were put forward. The result showed that decreasing the frequency of vibration motors or increasing the stiffness of springs, and increasing excitation force can improve the vibration properties of the properties of the drill-punch mechanism.

Materials

Oxide and Sulfide Dispersive Precipitation in Ultra-low Carbon Steels

Delu Liu, Xangdong Huo, Yuanli Wang, Jie Fu, Yongin Kang, Nanjing Chen

2001, 8(4): 314-315.

中文摘要(142) PDF(8) SpringerLink

摘要:

留言板

2001年第8卷第4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

2001年 第8卷 第4期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

2001年第8卷第4期