Effect of Nano-Al2O3 on the Properties of Ultra High MolecularWeight Polyethylene Engineering Material

The composite material of nano-Al 2O 3 and UHMW-PE was made by the way of pressing and agglomeration. Effect of nano-Al 2O 3 on the friction, wear characteristic of Ultra High Molecular Weight Polyethylene plastic was studied by using MPV-200 model friction and wear tester and caustic wear one. At the same time, the hardness of UHMW-PE was mensurated in sclerometer. The results showed that nano-Al 2O 3 not only decreases the friction coefficient of UHMW-PE, but also greatly reduce the wear of UHMW-PE.The hardness of UHMW-PE is improved. Which possesses important theoretic significance for optimizing of structure and property of UHMW-PE material.     

Study on Friction and Wear Performance of Ultra High Molecular Weight Polyethylene Plastic Composite Material

The friction and wear properties of Ultra High Molecular Weight Polyethylene(UHMW PE) composites filled with MoS 2,PTFE,carbon fiber,glass fiber and graphite are studied by using MPV-200 model friction and wear tester and caustic wear one. Experiment results show that graphite,MoS 2,PTFE reduce the friction coefficient of UHMW PE, but glass fiber increases the friction coefficient of UHMW PE, graphite not only reduces the friction coefficient of UHMW PE, but also can greatly reduce the wear of UHMW PE. At the same time, the effects of wear time,rate and load on the friction and wear characteristic of plastic alloy composite material are studied.     

Experimental Study on the Frictional Performance of Water Lubricated Plastic Alloy Bearings

It''s difficult to form hydrodynamic lubrication because of the low viscosity of water, but it is founded by experiment that there is low co-friction on water lubricated plastic alloy bearings working. The main factors that affect co friction are revs, loaded and clearance. Significance and effect of every factor that affect co friction is analyzed by variance analysis and orthogonal experiment. goaphs of every factor that affect co friction are list. From the goaphs, it is founded that there is elastic hydrodynamic because of elastic deformation in the plastic alloy.     

Separation and Analysis of the Ferroferric Compounds from Different Valence States in Lubricating Oil

The separation and analysis methods of ferroferric compounds in lubricating oil during mechanical transmission friction process are discussed in this paper.Owing to the iron and iron ion entered in lubricating oil yielding the wear and erosion of iron base alloy material.The separation of small wearing particles in lubricating oil and the measurement of iron are studied especially.The reliability of these methods are also verified and judged.     

IMPROVING ULTRA-HIGH MOLECULAR WEIGHT POLYETHYENE(UHMW-PE)FIBRE SURFACE ADHESION BY PLASMA TREATMENT

It's very difficult to study high-strenth compositesbecause of the poor adhesion of polyethylene fibres caused by its specialstructural qualities.This paper reports a study of changing the surfacequalities of ultra high molecular weight polyethyene(UHMW-PE)fibres of different draw ratios by plasma and acid treatment.It alsodevotes to the experiments of measuring the fibre resin adhesion bythe pull out technigue,and studies the mechanism of the interface failureby SEM.The experimental results show that there's a significant impr-ovement in the adhesion between the UHMW-PE fibres and the resinafter the plasma treatment and it can be four times stronger,dependingupon the draw ratios of fibres and plasma parameters,The interfacefailure in the pull-out test involved developes along the fibre-resininterface within the fibre,and the skin of the fibre is peeled off.Theadhesion can be improved by combining the plasma etching technique andother methods of treating the surface of UHMW-PE fibre.     

Sliding friction test analysis of TiAlN/TiN coatings on 40Cr steel

TiAlN/TiN duplex coating is made on the surface of 40Cr steel by means of multi-arc ion plating technology. Carrying capacity and tribological properties of TiAlN/TiN duplex coating are investigated with a UMT-2 wear tester without lubrication. The surface morphology of wear specimens are observed by scanning electron microscope(SEM). Elements of wear scar center and their content are analyzed by EDS. Tribological properties of TiAlN/TiN coating are evaluated through comparing with 40Cr in friction coefficient and wear volume. The results show that tribological properties of TiAlN/TiN duplex coating is better than 40Cr. The TiAlN/TiN films is superior in reducing friction and wear resistance, and can successfully resist abrasive wear and adhesive wear.     

结构参数对水润滑橡胶合金轴承摩擦噪声的影响分析

为了研究水润滑橡胶合金轴承结构参数对其低速重载工况下摩擦噪声的影响,使用复模态分析方法建立了水润滑橡胶合金轴承系统仿真模型,采用专业仿真软件分析了不同摩擦系数及结构参数条件下摩擦噪声产生的概率,进而研究结构参数对摩擦噪声的影响,进行了平板型和圆弧型结构的水润滑橡胶合金轴承摩擦噪声的对比实验。研究结果表明,水润滑橡胶合金轴承的水槽半径大小、摩擦面形状以及摩擦副的摩擦系数对水润滑橡胶合金轴承的摩擦噪声有较大影响,而水槽的形状对轴承摩擦噪声的影响不大。对一定结构尺寸的水润滑橡胶合金轴承,水槽半径为4 mm、平面型摩擦面的结构可以大大减少轴承出现摩擦噪声的可能性,相关实验结果与计算结果是吻合的。     

机体弹性变形对主轴承润滑特性的影响

为揭示机体弹性变形对曲轴主轴承润滑特性的影响,在考虑整机体和曲轴弹性的条件下,建立发动机曲柄连杆机构多柔体动力学模型,耦合基于质量守恒边界条件的广义雷诺方程和Greenwood/Tripp接触模型,分析机体弹性变形对曲轴主轴承润滑特性的影响。结果表明：与刚性机体相比,计入机体弹性变形后,各主轴承的润滑特性随曲轴转角的变化趋势与将缸体处理为刚性时基本一致;润滑油平均端泄量和总摩擦功耗在一个工作循环内均变化较小;润滑油最小油膜厚度、最大油膜压力和轴承的最大粗糙接触压力在一个工作循环内的某些时刻变化明显。     

Artificial Neural Networks Models for Flow Stress during High Temperature Plastic Deformation of Al-Li Alloy

Using gained experimental data to develop the models of stable flow stresses at high temperature plastic deformation by statistical methods for alloy materials, precision of the models is poor and at the same time the processes of modeling are complicated with great workload. On the basis of the data obtained on Gleeble-1500 Thermal Simulator,the predicting models for the relation between stable flow stress during high temperature plastic deformation and deformation strain, strain rate and temperature for 1420 Al-Li alloy have been developed with BP Artificial Neural Network method. The results show that the model on basis of BPNN is practical and it reflects the real feature of the deforming process. It states that the difference between the real value and the output of the model is in order of 5 percent.     

INFLUENCE OF PLASMA TREATMENT ON SURFACE ENERGY OF UHMW-PE FIBRES

The fibre-resin adhesion has been reinforced by plasmatreatment on ultra-high molecular weight polythlene(UHMW-PE)fibres.This paper reports a study of the mechanism of the adhesion from thechanging of the surface energy.The experimental results show the surfaceenergy of the fibres has been greatly increased for plasma treatment andthus meets the prerequisite of fibre-resin adhesion.The fibres are comple-tely rinsed in the epoxy matrix.     

Advance in Spray Forming Technology and Its Prospect

Spray Forming technology gets involved with new materials preparation techniques in multiple domains such as powder metallurgy, fluent metal atomization, rapid cooling and non-equilibrium solidification. High performance alloy and metal matrix composite with high density, low oxygen content and microstructure featuring rapid solidification can be fabricated by spray forming. Spray forming, which is of short process flow, low cost, high deposition efficiency, flexible manufacture system, becomes a kind of near shape forming and rapid solidification technology with great prospect. Therefore the developing process history of spray forming technology is introduced and the current research and development status of spray forming technology in the fields of aluminum alloy, steel material, magnesium alloy, copper alloy and high temperature alloy and metal matrix composite is described. Multi-layer spray forming and in-situ reaction atomization spray forming are also discussed. In addition, evaluation and prospect for the technology are presented.     

PE编织布膜下移栽对烤烟生长及理化特性的影响

为了优化烟稻轮作烟区烤烟膜下移栽技术,以烤烟云烟87为材料,比较了一种可透光、透气、透水的聚乙烯透明编织布与普通农膜进行膜下移栽对烟株生长和理化特性的影响。试验结果表明,编织布下移栽烟株伸根期的根系和茎围生长速度明显快于普通农膜膜上及膜下移栽烟株;现蕾和打顶后的株高、茎围和节距也大于普通农膜膜上及膜下移栽烟株;中部烟叶单叶重及单位叶面积质量大于普通农膜膜上及膜下移栽的烟株,但叶片厚度减小;烟叶总氮和钾含量增加,氮碱比降低。编织布下移栽可有效促进湖南烟稻轮作烟区膜下移栽烟苗早生快发,增加叶片单叶重和干物质积累量。     

Dynamic Lubrication of Micro Gas Bearings at an Ultra High Speed

Micro bearings of Power MEMS are usually designed to work at an ultra high speed more than 10~(6) r/min in order to improve their specific energy. So the dynamic lubrication of micro gas bearings at an ultra speed is researched. First the micro structural characteristics of micro gas-lubricated bearings are investigated, and a method to caculate the load-carrying performance of micro dynamic gas-lubricated bearings is put forword. Then the designs of two typical micro dynamic gas-lubricated bearings that are used in micro gas turbines are vertified. Moreover, the parameters affecting the load-carrying performance of micro dynamic gas-lubricated bearings are analysed.     

地膜源头减量化技术可行路径探讨

为了有效减少地膜投入和减轻地膜残留,本研究分析了国内农用地膜应用现状,归纳了地膜源头减量化技术可行路径。指出地膜覆盖具有“覆膜面积大、应用区域广、覆盖作物多”的特点,地膜残留具有“时限积累性、区域差异性、分布多态性”的特征。认为旧膜重复利用、生物降解地膜替代、秸秆覆盖技术替代、保水剂施用、耕作栽培模式优化等5类技术在地膜减量投用方面具有一定可行性,但需进一步研究总结和配套完善。建议集成减量技术、减量产品和减量模式,构建综合配套应用体系是地膜源头减量化技术路径的发展方向。     

Action Mechanism Optimized Surface by Nanoparticles in Oil Lubricating under Friction

According to tribochemical reaction and modeling of action mechanism ,the action mechanism optimized by nanoparticles in oil lubricating under friction is studied .The surface of a couple material is optimized by the together action of three approach stated as follows: Firstly, the thickness and intensity of lubricating layers or films provided with the action improving tribological properties increase because of enrichment of nanoparticles on the surface or near surface of couple-material arising from short force. Secondly, new lubricating film is built because of tribochemical reaction concerned with nanoparticles enriched in surface under friction and wear. Thirdly, the surface of couple-material is optimized by nanoparticles, for instance machine polishing, filling and leveling up the tiny hole and crackle on surface.     

我国棉田残膜污染危害与治理措施研究进展

地膜覆盖技术的应用为我国棉花产量提升做出重大贡献.但随着聚乙烯地膜的长期使用,土壤残膜污染问题日益突出,影响棉田土壤环境和棉花可持续发展.综述了我国棉田地膜残留现状、分布特征及其对棉花生长的危害,从土壤结构变化、水分迁移状况、有害物质释放、土壤物质代谢、微生物种群结构等方面系统总结了棉田残膜污染的危害机制,归纳了现阶段...     

Experiments on heat loss characteristics in a fully opened cylindrical cavity receiver

The climate has a great impact on highway bridge rubber bearings than on building rubber bearings. In order to study the change of the mechanical properties during the life of the plain chloroprene rubber bearings of highway bridge under freeze-thaw cycle condition, the plain chloroprene rubber bearings were processed 25, 50, 75, 100 times by freeze-thaw cycle in the standard freeze-thaw chamber, then the axial compression tests were carried. The changes of the performance indicators in the bearing capacity , the ultimate compressive strength, vertical stiffness, elastic modulus under different freeze-thaw cycles were analyzed comparatively. The results show that the plain chloroprene rubber bearings are more prone to brittle failure after the freeze-thaw cycle, and the failure phenomena of steel plate exposing or cracks is more serious than the phenomena of the standard specimen. With the increase of the number of freeze-thaw cycle, the ultimate bearing capacity, ultimate compressive strength and compressive elastic modulus of the plain chloroprene rubber bearings decrease. The attenuation formula and decay curve in 50 years of ultimate compressive strength and elastic modulus of compression are analyzed by least square method, the trends of change are both in line with the exponential function. The mechanical properties of plain chloroprene rubber bearings of highway bridge significantly decreased under freeze-thaw cycle condition. therefore, the temperature ranges of plain chloroprene rubber bearings of highway bridge should be strictly controlled, and some suggestions, such as increasing its minimum applicable temperature, usng the natural rubber bearings as much as possible in cold regions, have been given.     

Externally Pressurized Gas Journal Bearings in Power MEMS of Quasi Gas Power Cycle

An original thermodynamic idea for Power MEMS, which is called as quasi gas power cycle, is proposed to further intensify energy density and simplify structure of Power MEMS. Because gas supply with preset high pressure is set up in the Power MEMS engine of quasi gas power cycle, it is convenient for the Power MEMS engine to employ externally pressurized gas bearings to improve the performance of its bearings. Therefore mal design philosophy and structural type of the hyrostatic journal bearing as well as the hyrostatic thrust bearing in the Power MEMS engine are investigated, considering the limiting factor on meso scale. Then the structural and operational parameters are analyzed, and the optimal designs of typical externally pressurized gas bearings are put forward. Moreover the feasibility of the externally pressurized gas bearings applied to the Power MEMS engine is further verified by the calculation of load-carrying capacity of the hyrostatic gas bearings.     

Analysis on dynamic performance of hydrostaticoil film bearing throttled by capillary

With the linearization of the flow in oil chambers, the continuity equation of flow and the dynamic equation of the shaft are built for the hydrostatic journal bearing and thrust bearing respectively. Next, the transfer functions of the two bearings with capillary throttle are deduced. Then, the performance of the two bearings is simulated in Matlab. In general, the simulation results are well matched to the experimental data provided by Guangzhou Machine Tool Research Institute. It indicates that both of the models can predict the dynamic characteristic of the two bearings. Finally, the dynamics response of the hydrostatic thrust bearing is studied in various rotational speed of the shaft. Also, the dynamic performances of journal bearing are simulated in changing of inlet pressure and thickness of oil film.