载荷动态特性对三体磨料磨损过程的影响

在自行研制的环 -块磨损试验装置上研究了三体磨损状态下矩形波载荷特性对磨损的影响 ,结果表明 1矩形波载荷和静载荷作用下试件的磨损过程一样 ,存在跑合期和稳定磨损期 ;2对应于某一载荷波形占空比Φc,磨损量最大。当载荷波形占空比Φ小于Φc时 ,磨损随Φ的增加而迅速增加 ;当Φ大于Φc 时 ,磨损随Φ的增加逐渐减小并趋于静态载荷下磨损     

三牙轮钻头材料Ni65的冲蚀磨损机制研究

针对三牙轮钻头流道内实际工况,研究了钻头材料N i65和对比材料N i67和N i60 35%WC的冲蚀磨损特性。结果表明:N i65和N i67的冲蚀磨损阶段分为跑合期和稳定期,N i65磨损机制主要是微切削,而N i67的磨损机制主要是疲劳损伤和微切削;而N i60 30%WC的冲蚀磨损阶段为跑合期与周期性的稳定磨损和严重磨损期,其磨损机制主要是硬质点的脱落和疲劳点蚀。在试验过程中均伴有空蚀磨损。     

残余应力对齿轮跑合性能影响试验对比分析

对于齿面残余应力不相同但其他参数相同的两对齿轮进行运转试验,同时在齿轮运转过程中进行铁普观察分析,以探究齿面残余应力对齿轮跑合过程的磨损特性的影响。首先,在齿轮运转试验台上对两对齿轮开展齿轮运转试验,两对齿轮分别安装在主副齿轮箱;然后,在齿轮运转过程中,利用铁谱分析仪分析从试验开始到铁谱浓度稳定时之间的数据;最后,利用Matlab对跑合阶段的铁谱浓度数据进行处理,得出不同残余应力时的跑合过程的磨损变化规律。试验结果表明:残余压应力对齿轮跑合过程有一定的影响,残余压应力越大,齿轮跑合过程中磨粒浓度越低,磨损速度越慢;残余压应力越大,整体齿轮跑合过程更加缓和,齿面磨合效果越好;残余压应力大的齿轮跑合后,正常磨损期的齿轮磨损特性更好。     

三体磨损状态下载荷动特性对摩擦面形貌的影响

在自行研制的环－块磨损试验装置上研究了在体磨损状态下矩形波载荷特性对摩擦面粗糙度变化的影响,结果表明：（１）随着磨程的进行摩擦面粗糙度将达到一个稳定值－平衡粗糙度Ｒｑ＾ｓ,其大小与摩擦面初始形貌无关;（２）对应于某一载荷波形占空比Хｃ,Ｒｑ＾ｓ最大,当载荷波形占空比Х小于Хｃ时,Ｒｑ＾ｓ将随Х的增加而迅速增加;当Х大于Хｃ时,Ｒｑ＾ｓ随Х的增加而减小并趋于静态载荷下的Ｒｑ＾ｓ。     

基于联接磨损的蜗杆副齿间载荷分配的计算

以空间啮合原理和联接磨损理论为基础,推导出蜗杆传动齿面的磨损平衡方程,得出了分析圆柱蜗杆跑合后齿间载荷分配的方法,实例计算了JB2318-79轴向圆弧圆柱蜗杆在一个360°内齿间载荷的分配及变化规律.为分析圆柱蜗杆的强度、润滑性能及齿面温度计算提供了理论依据.     

火焰喷涂PA1010/n-SiO2复合涂层干摩擦磨损性能

利用火焰喷涂法制备PA1010/n-SiO2复合涂层,并采用均匀试验设计方法研究涂层在干摩擦条件下同GCr15 钢环配副时的摩擦学性能;利用SPSS 12.0统计软件对试验结果进行回归分析, 建立涂层摩擦系数和磨损质量损失同pv值 (摩擦载荷与摩擦速度的乘积)相关性的数学模型;利用示差扫描量热仪(Differential scanning calorimetry, DSC)和扫描电子显微镜(Scanning electron microscope, SEM)对复合涂层的热性能和磨损表面形貌进行分析。结果表明,n-SiO2的加入能明显提高涂层的结晶性能、耐磨性能。当n-SiO2含量为1.5%时,复合涂层摩擦磨损性能最佳,在试验条件下磨损质量损失降低近4倍,摩擦因数降低23％,跑合期缩短44％,复合涂层与GCr15钢环对磨时的磨损机理主要为疲劳磨损和轻微的粘附 磨损。     

齿轮跑合的磨损机制研究

通过齿轮副跑合的模拟试验,得出齿轮副在跑合过程中磨损形式的转化规律。     

圆弧齿轮跑合分析

从润滑、磨损和接触力学3方面对圆弧齿轮的跑合机理进行探讨,推导了跑合后油膜厚度计算公式,分析了不同齿面的跑合磨损量,确定了齿面法向磨损量的影响因素,最后指出圆弧齿轮的初始接触区对跑合有重要影响。     

SiCp增强铝基复合材料与Kevlar增强摩擦材料摩擦副摩擦磨损机理研究

采用盘销式摩擦磨损试验机，对SiCp含量为20vol％的铝基复合材料和Kevlar增强摩擦材料组成的摩擦副在于摩擦条件下的摩擦磨损机理进行了实验研究。结果表明：摩擦副在跑合过程中，铝基复合材料中的SiCp颗粒对较软的有机复合材料产生犁削和微观切削效应，磨损机理为铝基复合材料的硬质颗粒对较软的有机复合材料的磨粒磨损；在跑合后的磨损试验中，摩擦材料磨损表面呈现出粘着磨损和塑性变形特征，随着转动速度的增加，塑性流动加剧；摩擦副接触表面发生材料的相互转移，并在铝基复合材料表面形成转移膜，且在较高速度下转移膜更易形成；在高速条件下，摩擦材料表面可见从铝基复合材料的铝合金基体中脱离的SiCp颗粒和熔融迹象；摩擦材料的磨损机理主要为磨粒磨损、粘着磨损和塑性变形。     

基于流体机械工况的冲蚀磨损特性研究

在圆盘式磨蚀试验台上，对流体机械常用材料HT200、45与40Cr钢进行了模拟实际工况的冲蚀磨蚀试验，研究了试验材料的表面失效规律及微观破坏机理。结果表明：冲蚀分为跑合期、稳定期和上升期三个阶段。灰铁HT200的冲蚀磨损以脆性断裂为主；45钢的冲蚀磨损是以切削磨损为主；40Cr是以犁沟剥落为主。     

A Macro-scale Approximation for the Running-in Period

The article presents asymptotic modeling of the running-in wear process with fixed contact zone under a prescribed constant normal load or an imposed contact displacement. The wear contact problem is formulated within the framework of the two-dimensional theory of elasticity in conjunction with Archard’s law of wear. The running-in process is considered at the macro-scale level, while the micro-processes associated with roughness changes, tribomaterial evolution, and microstructural alteration in the subsurface layers as a first approximation are neglected. The setting of the steady-state regime for the macro-contact pressure evolution is chosen as the criterion to characterize the completion of running-in. Simple closed-form approximations are derived for the running-in period and running-in sliding distance. The obtained results can be used for estimating the running-in period in wear processes where the evolution of the macro-shape deviations at the contact interface plays a dominant role.     

干摩擦条件下载荷动特性对摩擦面粗糙度的影响

在自行研制的环 -块磨损试验装置上研究了干摩擦状态下矩形波载荷特性对摩擦面粗糙度的影响 ,结果表明 :1随着磨程的进行 ,摩擦面粗糙度将达到一个稳定值—平衡粗糙度 ,其大小与摩擦面初始形貌无关 ;2当载荷波形占空比 φ较小时 ,平衡粗糙度 Rsq 对φ的变化敏感 ,且随 φ的增加而增加。当 φ足够大时 ,Rsq 几乎不随 φ而变化     

A partial elastohydrodynamic theory for the running-in process of hobbed gears

The running-in process of hobbed gears has been studied experimentally. The initial wear was found to be small although it increased with running speed and load. To explain the results, a simulation procedure was developed that was based on a random surface model and a proposed relation between film thickness, surface roughness and running conditions. A new oil model was used for the analysis of conditions between meshing rough flanks. The wear and deformation of asperities during the running-in period is due to direct contact between the asperities. The parameters determining wear and deformation are the adhesion and temperature between the asperities in contact.     

复合润滑结构表面在油润滑下的减摩性能*

为研究不同表面处理方式对巴氏合金/45钢配副表面减摩性能的影响,采用热压固化工艺将六方氮化硼封装于表面织构内,制备复合润滑结构表面;在油润滑下进行销-盘磨损试验,使用递归定量分析（Recurrence quantification analysis,RQA）参数划分磨损过程;研究复合润滑结构表面在磨合期和正常磨损期的减摩性能,并与纯织构表面减摩性能进行对比。结果表明：复合润滑结构表面拥有较低摩擦因数和显著减摩效果,其减摩性能优于纯织构表面;相比无织构表面,复合润滑结构表面在磨合期内的平均摩擦因数下降77.9%,在正常磨损期内的平均摩擦因数下降73.5%且磨合期的时长缩减75.0%;较大织构孔径的复合润滑结构表面的减摩效果更好且磨合期更短;纯织构和复合润滑结构表面的减摩效果均在较高速度和载荷下更显著;各试样表面在磨合期的摩擦因数越低,对应进入正常磨损期后就越低。     

A Novel Running-in Method for Improving Life-Time of Bulk-Fabricated Silicon MEMS Devices

A running-in process is usually intentionally employed as an effective way to make friction pairs in macro-scale machinery more suitable for heavy load conditions. For silicon-based microelectromechanical systems (MEMS) with rubbing parts, however, even a short-time period of running-in under air or nitrogen environment can induce severe damage on rubbing surfaces, which prohibits any possibility of continuing operation. In this article, we demonstrate a new running-in process for MEMS devices, which can effectively reduce undesirable initial wear and thus generate an endurable bearing surface. The new running-in process consists of two steps of tapping treatment. A home-made microfriction test system has been developed to evaluate the effectiveness of this method. Through the tapping treatments, bearing spots on the rubbing sidewalls are restricted on several dominant locations, and the spreading of wear scar often observed in the test conditions without the tapping treatments is eliminated. After the running-in process, the life-time of the tested silicon MEMS devices has been extended in dry nitrogen test environment from 1?min to more than 1?h.     

Running-in wear of a compression ignition engine: Factors influencing the conformance between cylinder liner and piston rings

The conformance between the liner and rings of an internal combustion engine depends mainly on their linear wear (dimensional loss) during running-in. Running-in wear studies, using the factorial design of experiments, on a compression ignition engine show that at certain dead centre locations of piston rings the linear wear of the cylinder liner increases with increase in the initial surface roughness of the liner. Rough surfaces wear rapidly without seizure during running-in to promote quick conformance, so an initial surface finish of the liner of 0.8 μm c.l.a. is recommended. The linear wear of the cast iron liner and rings decreases with increasing load but the mass wear increases with increasing load. This discrepancy is due to phase changes in the cast iron accompanied by dimensional growth at higher thermal loads. During running-in the growth of cast iron should be minimised by running the engine at an initial load for which the exhaust gas temperature is approximately 180 °C.     

Initial wear of gears

Running-in experiments have been made in a back-to-back gear test rig with hobbed and shaved gears of quenched and tempered steels at different steels at different speeds and loads. Measurements of surface roughness and examinations of surface replicas were used to study the running-in process. The present results show that the running-in period corresponds to less than about 0.3×10⁶ revolutions. The initial wear is rather small but increases with running speed and applied load     

Friction and wear of self-mated SiC and Si3N4 sliding in water

The friction and wear of self-mated SiC and Si₃N₄ with different initial roughness sliding in water were investigated with pin-on-disk apparatus at normal load of 5 N and sliding speed of 120 mm/s in ambient condition. It was found that, for self-mated Si₃N₄, the wear mechanism for surface smoothening to obtain low friction was tribochemical wear, but for self-mated SiC, it changed from mechanical wear into tribochemical wear with increasing sliding cycles. After running-in in water, self-mated Si₃N₄ exhibited lower steady-state friction coefficient than self-mated SiC did. For these two ceramics, initial and steady-state friction coefficients were hardly dependent on initial roughness. Initial roughness mainly affected the running-in period. The larger the initial roughness, the longer the running-in period, but the running-in period was much shorter for self-mated Si₃N₄ at each initial roughness than that for self-mated SiC.     

Stability analysis of running-in system based on Nyquist curve of friction vibration

This paper examines the stability of the running-in process using a Nyquist curve analysis of the vibration due to friction. The Nyquist stability criterion uses the frequency characteristic to assess the stability of systems; so when the (−1, j0) point is enclosed by Nyquist curve, the closed-loop system is unstable. Running-in and wear tests of a piston ring against a diesel engine cylinder were conducted on a pin-on-disc tester. The analysis showed when the running-in is confined to the surface layers, the point (−1, j0) is not enclosed by the Nyquist plot and the process is stable; When the running-in is in the severe wear stage, the point (−1, j0) is enclosed by the Nyquist plot, the system is unstable; When running-in is in the stable wear stage, the point (−1, j0) is not enclosed by the Nyquist plot and the process is stable. This method could be used to predict the progress of the running-in process and identify the run-in state.