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Effect of fretting amplitudes on fretting wear behavior of steel wires in coal mines

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mining science and technology 2010年第6期20卷 803-808页

作者： SHEN Yan, ZHANG Dekun, GE Shirong school of materials science and engineering, china university of mining & technology, xuzhou 2.1116, china [a] school of materials science engineering China University of Mining & Technology Xuzhou 221116 China

Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.

关键词： steel wires fretting wear fretting amplitude fretting regime wear mechanism

Effects of Plasma Nitriding on Microstructure and Tribological Properties of CoCrMo Alloy Implant materials

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Journal of Bionic engineering 2010年第4期7卷 337-344页

作者： Qingliang Wang,Lei Zhang,Jiandong Dong school of Material science and engineering,china university of mining & technology,xuzhou 2.1116,P.R.china [a] school of Material science engineering China University of Mining & Technology Xuzhou 221116 P. R. China

Medical forged CoCrMo alloy was treated by plasma nitriding *** microstructures were characterized by 3Dprofiler,SEM and *** tribological properties were investigated under lubrication of 25% bovine serum *** that plasma nitriding is a promising process to produce thick,hard,and more wear resistant layers on the surface of *** nitrided samples showed an important increase in the surface hardness due to the formation of harder CrN andCrN phases with compact nano-crystalline *** typical hardness values of HVincreased almost two times thanuntreated *** bovine serum lubrication,at low nitriding temperature the Coefficient of Friction (COF) of nitrided samplewas lower than that of untreated sample,but at high nitriding temperature the COF was almost the same as the untreated *** with the untreated sample,the nitrided samples showed lower wear rates and higher wear resistance under differentnitriding *** adhesive wear is the main mechanism for untreated CoCrMo alloy and the wear mechanisms ofnitrided ones are the fatigue wear and slight adhesive *** is concluded that the improvement of wear resistance is ascribed tothe hard nitride formation of CrN and CrN phases at the nitrided surfaces.

关键词： CoCrMo alloy plasma nitriding microstructure friction and wear

Study on Biotribological Behavior of the Combined Joint of CoCrMo and UHMWPE/BHA Composite in a Hip Joint Simulator

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Journal of Bionic engineering 2009年第4期6卷 378-386页

作者： Qingliang Wang, Jinlong Liu, Shirong GeCollege of materials and engineering, china university of mining and technology, xuzhou 221007, P. R. china [a] College of materials engineering China University of Mining technology Xuzhou 221007 P. R. China

UHMWPE composites reinforced with Bovine Bone Hydroxyapatite(BHA)in different contents were prepared by heat pressing formation method.A hip joint wear simulator was used to investigate the biotribological behavior of UHMWPE/BHA composite acetabular cups against CoCrMo alloy femoral heads in bovine synovia lubrication at 37±1 ℃.It was found that the addition of BHA powder to UHMWPE can improve the hardness and creep modulus of UHMWPE/BHA composites,and decrease their wear rates under bovine synovia *** the content of BHA filler particles was up to 30 wt%, UHMWPE/BHA composites demonstrated the well design performances of the surface and biotribological ***, ploughing and slight adhesive wear were the main wear mechanisms for UHMWPE and its *** addition,the sizes of wear particles became larger with an increase in BHA powder *** results suggest that BHA filler is a desirable component to increase the wear resistance of UHMWPE/BHA composites for biomedical applications.

关键词： UHMWPE hydroxyapatite biotribology joint prosthesis

Preparation of semi-solid AlSi7Mg alloy slurry with big capability

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Rare Metals 2010年第6期29卷 642-645页

作者： LI Sha and MAO Weimin school of materials science and engineering,university of science and technology Beijing,Beijing 100083,china school of materials science and engineering University of Science and Technology Beijing Beijing China

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic *** effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were *** results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be *** new technology can save energy and make the pouring process *** the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to *** the alloy melt is poured at the temperature（630°C） with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic *** the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value（1.72 kW）,the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.

关键词： aluminum alloys metal forming semisolid slurry electromagnetic stirring microstructure

Application of mesoscale modeling optimization to development of advanced materials

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Progress in Natural science:materials International 2004年第8期14卷 8-15页

作者： SONG Xiaoyan(school of materials science and engineering, Beijing university of technology, Beijing 100022, china) Beijing Univ Technol Sch Mat Sci & Engn Beijing 100022 Peoples R China

The rapid development of computer modeling in recent years offers opportunities for materials preparation in a more economic and efficient way. In the present paper, a practicable route for research and development of advanced materials by applying the visual and quantitative modeling technique on the mesoscale is introduced. A 3D simulation model is developed to describe the microstructure evolution during the whole process of deformation, recrystallization and grain growth in a material containing particles. In the light of simulation optimization, the long-term stabilized fine grain structures ideal for high-temperature applications are designed and produced. In addition, the feasibility, reliability and prospects of material development based on mesoscale modeling are discussed.

关键词： mesoscale computer simulation Monte Carlo technique deformation recrystallization grain growth.

C^MC^N D-computable state

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science china(Physics,Mechanics & Astronomy) 2008年第9期51卷 1300-1307页

作者： LIU DongDong1,2 & DI YaoMin1 1 school of Physics & Electronic engineering,xuzhou Normal university,xuzhou 2.1116,china 2.school of Mathematics & Physics science,xuzhou Institute of technology,xuzhou 221008,china 1. school of Physics & Electronic engineering Xuzhou Normal University Xuzhou 221116 China 2. school of Mathematics & Physics science Xuzhou Institute of Technology Xuzhou 221008 China

The notions of D-computable state and D-concurrence are generalized to the CMCN system. A class of D-computable state on CMCN is given and the calculating method of the lower bound of D-concurrence is provided. Th... 详细信息

关键词： quantum entanglement entanglement of formation concurrence D-computable state

A new method for mining deformation monitoring with GPS-RTK

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中国有色金属学会会刊：英文版 2011年第S3期21卷 659-664页

作者： GAO Jing-xiang1, 2, LIU Chao2, WANG Jian1, 2, LI Zeng-ke2, MENG Xiang-chao2 1. Key Laboratory for Land Environment and Disaster Monitoring of State Bureau of Surveying and Mapping, china university of mining and technology, xuzhou 2.1116, china 2. school of Environment and Spatial Informatics, china university of mining and technology, xuzhou 2.1116, china [a] Key Laboratory for Land Environment and Disaster Monitoring of State Bureau of Surveying and Mapping China University of Mining and Technology Xuzhou 221116 China [b] school of Environment and Spatial Informatics China University of Mining and Technology Xuzhou 221116 China

Based on ranging intersection theory, a new method which is simple and easy to operate was proposed for data collection in the mine surface deformation monitoring with GPS-RTK centering rod measurements. It can fully eliminate the inevitable shaking error and the vertical deflection, and to some extent weaken the multipath effect on the estimates of coordinates in a relatively short period of time, using high-frequency observations. The results show that three-dimensional coordinates with a height accuracy better than 1 cm, horizontal accuracy better than 2-4 cm can be achieved through only 15-30 s continuous observation by 20 Hz high-frequency and effectively improve the measurement accuracy and efficiency of RTK, fully satisfying the high-speed and high-precision data acquisition in mine surface subsidence deformation monitoring.

关键词： GPS rover pole multipath delay deformation monitoring

Description to wear debris boundaries by radar graph fractal method

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Chinese science Bulletin 2007年第16期52卷 2285-2290页

作者： LIU HongTao1,2 & GE ShiRong1 1 Institute of Tribology and Reliability engineering,china university of mining & technology,xuzhou 221008,china 2 College of Mechanical and Electrical engineering,china university of mining & technology,xuzhou 2.1116,china Institute of Tribology and Reliability engineering China University of Mining and Technology Xuzhou 221008 China

In this paper,radar graph fractal method is introduced to describe wear debris boundaries. Research results show that it is a nice way to describe wear debris boundaries. Since the longest axis is selected as the first coordinate axis,its center point selected as the center point of the radar graph,and the co-ordinate value of wear debris boundary selected as the measure parameter,the limitations existing in Yard fractal measure method can be avoided. For any wear debris,its radar graph fractal dimension value is one and only,and as the wear debris shape changes from round to strip,the radar graph fractal dimension value also changes from low to high,showing strong uniqueness and independence. Due to the fact that the researched wear debris is gotten in different wear states,the results also prove that radar graph fractal dimension value is correlated with frictional pairs work condition and wear state. Radar graph fractal method is compared with Yard fractal measure methods,and results show that ra-dar graph fractal dimension values gotten from different wear debris have enough value grads to avoid effect of errors,and provide higher sensitivity for wear debris shape. This paper also discusses the influencing factors for radar graph fractal method. With the increase of the decomposing degree value,the radar graph fractal dimension tends to keep stable at one certain value,showing the typical characteristic of the fractal theory. All this proves that radar graph fractal method is an effective description method for wear debris boundaries.

关键词：磨粒边界雷达图表分形法

Comparison of Concrete Carbonation Process under Natural Condition and High CO_2 Concentration Environments

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Journal of Wuhan university of technology(materials science) 2010年第3期25卷 515-522页

作者：姬永生 State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and Technology Xuzhou school of Mechanics & Civil engineering China University of Mining and Technology Xuzhou

To compare the results obtained under both natural and accelerated environments,the pH values of carbonated concrete were measured,the variation of pH values was determined,and the variations of Ca（OH）2 and CaCO3 contents in the carbonated concrete under natural condition and high CO2 concentration accelerated climate environments were determined by microcosmic test methods such as DTA and X-ray *** experimental results showed that the overall variation trend of pH values and phase component of carbonation layer of concrete under accelerated climate environments with high CO2 concentrations were the same as those under natural ***,the carbonation processes of concrete were considered consistent under both *** there was a difference in the length of semi-carbonation *** one measured under high CO2 concentration accelerated climate environments was shorter than that under natural *** investigation showed that it was caused by the differences in climate condition（temperature and relative humidity） as well as the properties of the *** concentration of CO2 and the duration of the carbonation process have no effect on the length of semi-carbonation ***,it is acceptable to simulate the natural condition by applying the high CO2 concentration artificial accelerated carbonation technique for the purpose of the study of carbonation process of concrete.

关键词： natural carbonation artificial accelerated carbonation phase component semi carbonation zone correlation