A tribological study of kinetically influenced ultrathin Au and Cu metal overlayers grown on dendrimer mediated Si

Evidence is presented here for deposition kinetic energy influences on the wear properties of Au and Cu films deposited by evaporation and sputtering on clean and poly(amidoamine) (PAMAM) dendrimer modified SiO _x substrates. Ramped load nanoscratch tests show increased resistance to wear in the presence of the dendrimer monolayer. Nanoscratch profiles indicate that the critical load to failure (scratch bearing capacity) is increased in the presence of a dendrimer interlayer. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis of the wear tracks show that following film failure plowing is the predominant mechanism of wear for sputtered or evaporatively deposited Au. No obvious changes in the wear properties (a pure cutting mechanism) of Cu thin films are observed upon changing the kinetic energy of the incoming metal.     

恒定动能作用下薄壁管的冲击微动磨损行为研究

在新型冲击微动磨损试验机上对四种常见材料的薄壁管(不锈钢、铜合金、纯钛和铝合金)进行了冲击磨损试验,考察了材料属性、冲击能量对薄壁管损伤行为的影响。对其冲击动力学行为、磨损行为进行了分析。研究结果表明,不同材料金属管的能量吸收率、冲击接触力和冲击管变形有显著差异;同一种材料,随着初始冲击动能的增大,冲击过程中接触力、冲击管变形和冲击吸收能也在增大。通过分析磨痕微观形貌和磨痕轮廓,发现薄壁管的冲击磨损抵抗性能与材料属性密切相关;随着初始冲击动能的增加,材料损伤加剧,其损伤机制为疲劳磨损。     

Particle size effects on the slurry erosion of aluminium alloy (AA 6063)

The effect of particle size on erosion wear of aluminium alloy (AA 6063) has been investigated in a slurry pot tester. Eight different sized quartz particles with mean size varying between 37.5 and 655 μm have been used. The wear specimens are rotated inside the pot at 3 m/s velocity with orientation angle of 30° and 90° in a sand–water mixture of 20% concentration (by weight). It is seen that the erosion wear increases with increase in mean particle size. Two distinct mechanisms are noticed for mean particle size above 200 μm and below this size for the range of parameters under this investigation. It seems that a threshold kinetic energy of impacting particle may exist, which results in change in the wear rate at a particular particle size. The threshold kinetic energy for different operating conditions has been determined and its relation with the change in erosion mechanism is discussed.     

Effect of test parameters on large particle high speed slurry erosion testing

Abstract

A high speed slurry-pot wear tester was developed for close-to-reality heavy-duty wear testing of materials used in mineral applications. The samples are attached on four levels in a pin mill configuration. The tester and the developed sample rotation test method deliver reproducible results. This study focuses on the effects of testing parameters in large particle slurry testing. Parameters such as the speed, particle size and slurry concentration were varied. The effect of test duration was also examined. Round steel samples and slurry of water and granite gravel were used for testing. The test parameter variations were 4 to 10 mm for particle size, up to 23 wt-% for concentration and up to 20 m s^?1 for the sample tip speed. The relationships between the parameters are discussed. The kinetic energy of the large abrasive particles is also considered. Wear surfaces studied with optical and electron microscopy are also presented and discussed.     

Prediction of fretting wear using boundary element method

The simulation method of the fretting wear prediction using boundary element method is developed. The contact pressure and the contact width which is the first step to predict fretting wear are obtained from contact analysis of a semi-infinite solid based on the use of influence functions and patch solutions. The geometrical updating is based on nodal wear depths computed using Archard’s equation for sliding wear. The prediction of fretting wear for two cases of contact problems is performed; one is two-dimensional cylinder on flat contact which is for the comparison with a previous model by finite element method; the other is three-dimensional spherical contact. It is observed that for two-dimensional cylindrical contact the boundary element method developed in this study reduced the calculation time by 1/48 compared to FE method. We also showed the use of developed simulation technique is efficient to predict the fretting wear for three-dimensional spherical contact.     

Optimization of abrasive waterjet machining using multi-objective cuckoo search algorithm

Abrasive waterjet (AWJ) machining is widely applied in the fields of civil and mechanical engineering. In this study, a general and theoretical analysis procedure was presented before computing application. It mainly focused on the kinetic energy model and wear rate model in machining process. Then, the multi-objective cuckoo algorithm was employed for optimization design of AWJ cutting head model, making sure to maximize the output energy and minimize the nozzle erosion rate while keeping the other factors constant. To demonstrate the effectiveness of the above strategy, a practical AWJ machining system was selected for investigation purpose. The proposed model was compared with experimental data for investigating the difference between the initial design and the optimized model. The results showed that the multi-objective cuckoo algorithm has great ability in prediction of outlet power and wear rate. Meanwhile, the optimized parameters were also superior to the original design, compared with experimental test data. The developed model can be used as a systematic approach for prediction in an advanced manufacturing process.     

平底直动从动件凸轮机构磨损失效分析及磨损量计算

凸轮轴和挺杆体是发动机的重要零件,它们的状况直接影响着发动机能否正常工作.文中研究了平底直动从动件凸轮机构运动模型和受力情况,并对其磨损失效成因、磨损形式、磨损规律进行了分析;剖析了相对滑动、润滑条件和接触应力对其工作环境的影响机理,建立了磨损计算模型;并提出从凸轮挺杆材料选配、润滑油、运动参数方面降低凸轮机构磨损的相应措施;提高了凸轮机构的工作可靠性,延长了工作寿命.     

含间隙曲柄滑块机构运动副动态磨损研究

含间隙曲柄滑块机构中运动副的润滑情况不同于滑动轴承,其相对速度不足以形成动压润滑而处于边界润滑状态下.为了分析此状态下的动态磨损问题,考虑到含间隙运动副边界润滑时轴套的切向弹性变形和切向阻尼,结合考虑间隙运动副碰撞接触的非线性弹簧阻尼模型,提出边界润滑条件下的间隙副接触力模型,进而在此基础上推导出间隙副的动态磨损模型,并对含间隙曲柄滑块机构的运动副动态磨损进行数值分析.计算结果表明副元素间呈现出连续弹性变形现象,在连续变形接触处,动态磨损量较大使磨损加剧,并出现非均匀磨损.     

Improvement of wear resistance of quenched structural steel by nanostructuring frictional treatment

The paper deals with the study of the structure, deformation hardening, and wear resistance under abrasive and sliding friction of quenched structural steel 50 (0.51% of C), which is subjected to frictional treatment by a hard alloy indenter. The resistance of a steel surface layer hardened by frictional treatment to mechanical effects is estimated using the kinetic indentation method. It is shown that frictional treatment yields a considerable increase in the wear resistance of quenched medium-carbon steel tested in pairs with flint and corundum, as well as under the conditions of adhesive wear and boundary friction, due to the hampering of the processes of microcutting, seizure, and plastic deformation. This is favored by the higher resistance of the nanostructured layer to residual deformation during contact loading.     

Influence of electrochemical potential on the wear of metals, particularly nickel

The wear of nickel and of alloy steels under the influence of an impressed potential is discussed in terms of a model which considers both the kinetic and thermodynamic properties of the metal/electrolyte reactions and of the electrochemical reactions of oxygen, hydrogen and water. The experimental data can be interpreted in terms of the electrochemical formation of an oxide film within the wear scar and its subsequent removal by mechanical action. The voltage range over which transitions to an increased wear rate occur are related to the Tafel slopes associated with metal dissolution reactions.     

凸轮机构磨损数值仿真软件研制

根据零件磨损过程一般数值仿真方法 ,以凸轮机构为研究对象 ,开发出不同类型凸轮磨损仿真软件 ,可实现不同极根条件下的凸轮磨损寿命预测、参数优化和状态监测等功能。     

Abrasive wear behavior of sintered steels prepared with MoS2 addition

Sintered steels containing molybdenum di sulphide powders were developed for application as bearings, gears, connecting rods, etc. Abrasive wear characteristics of these materials are investigated as the machine elements also need to have a good abrasive wear resistance. Materials with base composition Fe–C–Cu and Fe–C–Cu–Ni containing varying levels of MoS₂ were developed from elemental powders. Compressive strength, hardness and density are influenced by the addition of MoS₂. Abrasive wear tests were conducted by sliding against the SiC abrasive sheet at room temperature. MoS₂ added material exhibited a high coefficient of friction and good wear resistance compared to the base composition. The artificial neural network model developed predicts the wear volumes, which are in agreement with the experimentally measured data.     

Quantitative estimation of wear amounts by real time measurement of wear debris in lubricating oil

A diagnostic technique that can estimate quantitatively wear amounts under lubricated condition was developed using our developed on-line particle counter. Wear tests were carried out by rubbing a bearing metal against a carbon steel in paraffin oil. The size and number of wear debris in the circulating oil could be measured in real time. The volume of each debris was calculated and, additionally, the total wear amount during a given duration was calculated by accumulating all debris volume. The wear amounts obtained by the quantitative estimation were fairly similar to the measured values of mass loss of the specimen.     

A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise

This article describes how a wheel–rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab- and full-scale tests showed that noise could be used as an indicator of wear transition, when normal wear turns into severe or catastrophic wear. This transition was accompanied by a significant increase in sound pressure and a broader sound pressure amplitude spectrum; that is, a narrow initial amplitude distribution in the normal wear regime and a broader distribution in the severe wear regime. The measured noise from the inner/low and outer/high rails was analyzed in conjunction with the wear from the outer wheel and comparisons were made between cleaned (exposed to severe wear) and lubricated (no wear) rail. Based on those analyses, a wear detection parameter criterion was developed for this specific train. This wear parameter has been implemented in a real-time condition monitoring system so that warnings of the risk for severe wear could be sent to the maintenance department. Validation of the wear parameter and challenges linked to open system conditions are discussed in this article.     

690合金材料的微动磨损特性研究

利用微动磨损试验机,在载荷50N以及位移幅值为60μm、100μm、150μm的工况下,研究了690合金材料在常温下的微动磨损行为及其动力学特性,采用激光共焦扫描显微镜(LCSM)和扫描电子显微镜(SEM)观察磨痕微观形貌。结果表明,载荷和位移幅值对微动特征有很大的影响,微动运行完全处于滑移状态。在滑移区,滑移磨损严重、磨痕面积大。690合金材料的磨损机制主要表现为磨粒磨损与剥层的共同作用。     

齿轮传动中磨损问题的研究及修复方法

齿轮传动是机器传递运动和动力的一种主要形式.如何减少齿轮工作中的磨损、延长其使用寿命是工业生产中至关重要的问题.重点总结了齿轮磨损问题的基本类型、研究历程、研究方法以及对失效齿轮的常用修复方法等.     

Effect of Cycling Low Velocity Impact on Mechanical and Wear Properties of CFRP Laminate Composites

The mechanical and wear properties of CFRP laminate were investigated using a method of cycling low velocity impact, to study the trend and mechanism of impact resistance of the CFRP laminate under repeated impact during its service process. The interface responses of CFRP laminate under di erent impact kinetic energy during the cycling impact process were studied were studied experimentally, such as impact contact duration, deformation and energy absorption. The worn surface morphologies were observed through optical microscopy and a 3?D surface profiler and the cross?sectional morphologies were observed through SEM to investigate the mechanism of impact material dam?age. Based on a single?degree?of?freedom damping vibration model, the normal contact sti ness and contact damp?ing of the material in di erent wear stages were calculated. It shows the failure process of CFRP laminate damaged by accumulated absorption energy under the cycling impact of di erent initial kinetic energy. The results indicate that the sti ness and damping coe cients will change at di erent impact velocities or cycle numbers. The damage mechanism of CFRP laminates under cycling low kinetic energy is delamination. After repeated experiments, it was found that there was a threshold value for the accumulated absorption energy before the failure of the CFRP laminate.     

含碳量对20%Cr合金氧化和高温磨损性能的影响

对不同含碳量的20%Cr合金进行了900℃大气气氛下的抗氧化性试验,测定了在此温度下的氧化动力学曲线,并在自制的高温磨损试验机上进行了800℃的高温磨粒磨损试验。用扫描电镜及电子探针分析和测定了氧化、磨损面的形貌及其亚表层的组织及成分分布。试验表明,随含碳量增加,氧化过程由良性的外部氧化转向恶性的内部氧化,从而使合金的抗氧化性下降。合金中共晶碳化物（Cr,Fe）7C3在高温下有较高的硬度和稳定性,因此,合金含碳量的增加,提高了800℃时的抗磨性。在高温磨损过程中由于基体组织的变形而使碳化物折断。因此,基体抵抗变形的能力将对利用碳化物来提高合金的抗高温磨损性能起到重要的作用。     

Untersuchungen über die beeinflussung des gefüges karbidischer gusseisen bei abrasiver verschleissbean-spruchung

In this paper the mechanism of abrasive wear of white cast irons is examined on the microstructural scale. The Fe-C-Cr-Mo, Fe-C-Cr-Ni and Fe-C-V-Cr alloys were tested. The results of the test have shown that abrasive wear of white cast iron is the result of wear of the microstructural components. Under high-stress abrasion the carbide can be deformed, scratched, broken and uprooted. The matrix shows cutting and deformation work hardening and martensitic transformation. The abrasion behaviour of alloys with different microstructural matrices is markedly influenced by mechanisms of wear. During abrasion the austenitic matrix can undergo the form, the hardness, the kinetic energy and the pressure of abrasive particles.     

In-cycle monitoring of tool nose wear and surface roughness of turned parts using machine vision

Tool wear has been extensively studied in the past due to its effect on the surface quality of the finished product. Vision-based systems using a CCD camera are increasingly being used for measurement of tool wear due to their numerous advantages compared to indirect methods. Most research into tool wear monitoring using vision systems focusses on off-line measurement of wear. The effect of wear on surface roughness of the workpiece is also studied by measuring the roughness off-line using mechanical stylus methods. In this work, a vision system using a CCD camera and backlight was developed to measure the surface roughness of the turned part without removing it from the machine in-between cutting processes, i.e. in-cycle. An algorithm developed in previous work was used to automatically correct tool misalignment using the images and measure the nose wear area. The surface roughness of turned parts measured using the machine vision system was verified using the mechanical stylus method. The nose wear was measured for different feed rates and its effect on the surface roughness of the turned part was studied. The results showed that surface roughness initially decreased as the machining time of the tool increased due to increasing nose wear and then increased when notch wear occurred.