Influence of Surface Groove Width on Tribological Performance for Cylinder Liner–Piston Ring Components

Surface groove width is of great significance to the performance of the cylinder liner–piston ring (CLPR) with the different surface textures in marine diesel. However, little is understood about the specific application (e.g., the geometric parameters of surface textures and operating conditions) of surface texture in actual marine diesel engines. To address this issue, different surface groove textures including grooves structures with 1-, 2-, 3-, and 4-mm widths were designed based on previous results related to marine diesel engine applications. A series of experimental tests was conducted in a reciprocation tester, and data on the friction characteristics were obtained under different operating conditions. Comparative studies on the friction coefficients, worn surface features, and oil film characteristics were performed. Results showed that the 2-mm groove structure of the cylinder liner was more favorable for improving the wear performances at low speed, whereas a 3-mm groove structure of the cylinder liner was more suitable for improving the wear performance at higher speeds, though its wear performance needs to be improved under high load. These results help to understand the specific application of surface texture on the wear performance of the CLPR pair.     

Study on Influence of Cylinder Liner Surface Texture on Lubrication Performance for Cylinder Liner–Piston Ring Components

A marine diesel engine, where the cylinder liner–piston ring (CLPR) pair is one of the most important rubbing pairs, is the heart of a marine system. Studying the lubrication characteristics of the CLPR will provide a guide for rational design of the CLPR to reduce wear and prolong its service life. The surface texture features have a significant impact on the lubricating performance of the CLPR. In this study, the tribological system of the CLPR was investigated. Different surface textures (such as different sizes of surface concaves and grooves, etc.) were designed and produced on the cylinder liners using surface treatment. A series of experimental tests were then carried out in a specially designed diesel engine tester to investigate the tribological characteristics of the treated CLPR pairs. The comparison analyses of the worn surface texture features, element content of the lubrication oil, and abrasive particle characteristics were conducted under different wear surface texture features and cylinder liner speeds. The analysis results showed that there were significant differences in the tribological and lubrication properties of the rubbing pairs in different wear surface texture features. The wear performance of the CLPR pair with a regular concave texture was superior to that of the concave and groove, and regular groove textures. In addition, the regular concave with a depth-diameter ratio of 0.1 was the most effective surface texture to improve the lubrication and wear properties of the CLPR pairs. It is believed that the knowledge obtained in this study provides the real practical basis for tribological design and manufacturing of CLPR pair in marine diesel engines.     

仿生织构形态对缸套-活塞环摩擦学性能的影响

为了提高缸套-活塞环的摩擦学性能,设计了一种仿生排布的菱形凹坑织构,并通过激光刻蚀技术在缸套表面进行加工;在同一转速和不同载荷下,在MWF-10往复式摩擦磨损试验机上进行试验,以探究仿生排布的菱形织构对缸套-活塞环摩擦副摩擦磨损性能的影响,并与使用阵列排布的纹理的缸套以及未经处理的原始缸套进行比较。结果表明:织构的排布形式对油膜厚度的影响较大,尤其在重载荷工况下,合理地优化排布形式能够实现较好的动压润滑效果;仿生排布的菱形织构实现了往复运动方向上纹理特征的全覆盖,能够极大程度上限制磨屑的移动并对磨屑进行收集,有效降低磨损后的表面粗糙度,从而减少磨粒磨损;仿生排布的菱形织构在各试验工况下能够有效提高油膜厚度,提升表面承载能力,实现最佳的润滑效果。     

A Study on the Tribological Behavior of Surface Texturing on Babbitt Alloy under Mixed or Starved Lubrication

Aiming at improving the tribological performances of sliding bearings in mixed or starved lubrication regime, textures in square and linear radiating arrays are ablated on the surface of Babbitt alloy disks by laser radiation. Series of pin-on-disk wear tests and computational fluid dynamics (CFD) analysis are conducted to investigate the influence of distribution and geometry of the textures under various operating conditions. Results suggest that surface texturing suitably interacts with the material properties of Babbitt metal favorably improving its tribological performance. Friction coefficients of the disks with textures arrayed in square are generally much lower and more stable as compared to their counterparts with textures arrayed in linear radiation. Also, textures arrayed in a square with an area density of 8.6 % allow the lowest friction coefficient, as low as 0.015, to be achievable. Theoretical analysis sheds the light that proper texture arrangements tend to generate favorable distribution of micro-hydrodynamic pressure to improve the tribological performance of Babbitt alloy significantly.     

凹坑织构对石墨材料水润滑性能的影响

为提高核主泵屏蔽电机用水润滑石墨轴承的摩擦润滑性能,采用高速雕铣机在石墨试样表面加工不同形状、深度和面积占有率的凹坑织构,通过水润滑条件下的销盘摩擦试验,测试分析凹坑织构结构参数对石墨材料水润滑性能的影响。结果表明：在水润滑条件下凹坑织构具有一定的减摩效果,随着转速的增加,凹坑织构的动压效应增强,石墨试样摩擦因数减小;随着载荷的增加,石墨试样摩擦因数减小;随着凹坑深径比、面积占有率的增加,石墨试样摩擦因数均呈现先减小后增大的变化趋势,当凹坑深径比为0.5、凹坑面积占有率为3%左右时,石墨试样摩擦因数最小;相较三角形凹坑织构,正方形凹坑和圆形凹坑织构的减摩效果更好。     

重型车辆织构化刹车系统热力学行为与摩擦学性能研究

重型车辆刹车系统受瞬态高温和雨水异常侵入的影响,易引起热力学行为与摩擦性能退化。为研究表面织构对刹车系统热力学行为和摩擦学特性的影响,基于有限元法开展刹车系统热力学分析,考虑大量雨水侵入的液体润滑极端情况,提出一种动压润滑与织构集成模型的摩擦学性能分析方法。结果表明：水平凹槽织构可使制动盘温度场及应力场分布较均匀,进而避免接触区域局部瞬态高温引起的车辆制动失效;随着凹槽织构倾斜角度增大,承载力增大,摩擦因数减小;不同组合型织构中,圆柱与椭球组合型织构表面承载力最大、摩擦因数最小,圆锥与椭球组合型织构表面承载力最小、摩擦因数最大。研究发现重型车辆刹车系统表面构筑合适倾斜角度凹槽织构和组合型织构有助于提升其工作性能。     

表面织构排布方式对径向滑动轴承摩擦性能的影响

基于Navier-Stokes方程,建立表面织构化滑动轴承数值分析模型,采用压力耦合方程的改进半隐式(SIMPLEC)算法进行求解,分析表面织构排布和形状对滑动轴承摩擦性能的影响。结果表明：在收敛楔入口排布十字形织构时可以显著提高承载能力;在收敛楔中部周向排布沟槽和短沟槽织构比轴向排布更能显著改善轴承摩擦性能,且排布倒椭圆、菱形和十字纹理可以更明显地改善滑动轴承的摩擦性能;在收敛楔出口排布织构不能改善滑动轴承的摩擦性能,而在发散楔只有三角形织构可以改善轴承的摩擦性能。设计5种新型复合织构排布方式,分析其对轴承摩擦性能的提升效果。结果发现：复合型织构比单一类型织构更有利于提高轴承摩擦性能,其中在收敛楔入口布置十字形织构,收敛楔中部分别布置周向沟槽、短沟槽和十字形织构,发散楔布置三角形织构的3种复合型织构设计轴承性能提升效果显著,使承载力分别提高了15.69%、15.66%和17.16%,摩擦因数降低了3.75%、4.17%和2.92%。     

SLM成形表面织构对TC4钛合金干摩擦磨损性能的影响

基于一步法思路,采用金属3D打印机基于激光选区熔化（SLM）技术制备表面带有凹坑织构的TC4钛合金试样,采用光学相机、超景深显微镜和扫描电镜观察织构成形情况,利用激光共聚焦位移测试仪和显微维氏硬度计分别测试表面粗糙度和表面硬度,在干摩擦条件下采用摩擦磨损试验仪考察不同载荷下织构密度对TC4钛合金试样摩擦学性能的影响,并使用扫描电镜对摩擦实验前后的表面形貌进行分析。研究结果表明：一步法SLM成形能够在TC4钛合金表面获得成形良好的直径500 μm的织构;随着织构密度的提高,钛合金试样表面粗糙度增大,表面硬度有所降低;干摩擦条件下,提高TC4钛合金试样织构密度有利于磨屑的收集从而减少试样的三体磨损,提高载荷有利于改善摩擦副接触状态;5 N载荷下40%织构密度试样的平均摩擦因数和磨痕宽度均最小,与无织构试样相比,平均摩擦因数和磨痕宽度分别降低12%和16%;40%织构密度下,载荷提高会引起摩擦因数的降低和磨损量增大,磨损表面犁沟和片状剥落增多。在干摩擦条件下,3D打印一步法制备的表面织构可以显著改善TC4钛合金的磨粒磨损和黏着磨损。     

304不锈钢表面离散圆形凹坑液相辅助激光制备及摩擦性能

为改善304不锈钢耐磨性及润湿性，在空气与液相2种介质下使用激光加工技术在304不锈钢表面制备离散型圆形凹坑织构。借助白光干涉仪、扫描电子显微镜及能谱、接触角测量仪对织构试样表面形貌、元素含量及润湿性进行了表征，并通过摩擦磨损试验考察了织构试样在干摩擦和油润滑下的摩擦学性能。结果表明：空气介质下激光加工增强了试样表面疏水性能，接触角为123.3°；液相辅助激光加工增强了试样表面润湿性，接触角为29.3°；液相辅助激光加工表面的微凹坑分布更加均匀，无明显的氧化及熔融物重铸现象，这是因为液相在激光加工时对试样起到了冷却及保护作用；液相辅助激光加工表面织构在2种摩擦工况下的摩擦因数均最小，且磨损有一定改善。液相辅助激光制备的织构表面较为均匀、无较大的微凸峰，且具有较好的润湿性能，有利于润滑油的存储及铺展，进而改善了界面摩擦行为。     

复合工艺制备的表面微凹坑织构的摩擦性能研究

在构建的激光电化学复合微加工系统上,采用皮秒脉冲激光辐照与电解刻蚀复合加工方法在7075铝合金表面制备出不同尺寸的阵列凹坑微织构。采用共聚焦显微镜观测复合加工织构试样表面形貌,采用MFT-5000型RTEC摩擦磨损试验机研究润滑条件下凹坑织构的摩擦学性能,并探讨直径、深度、面积密度对减摩性能的影响。结果表明:复合加工工艺制备的表面微织构具有良好的表面形貌;润滑条件下材料表面的凹坑型织构能显著改善其摩擦学性能,相比光滑表面最高可降低摩擦因数30%;在实验参数范围内,凹坑的直径与面积密度对材料表面摩擦性能影响较大,凹坑深度对摩擦性能影响较小。     

弹性材料表面织构对摩擦副润滑性能的影响

为了研究弹性材料表面微织构对摩擦副空化现象和润滑特性的影响,建立考虑空化效应的二维弹性织构计算模型,采用流固耦合方法计算润滑流场与材料变形之间的相互作用。对比刚性材料表面微织构,从弹性模量、滑动速度、微织构深度以及织构间距等方面分析弹性材料表面织构对摩擦副润滑性能的影响,通过实验验证模拟结果的准确性。结果表明：弹性织构摩擦副比刚性织构摩擦副摩擦因数更小,润滑性能更好;存在最优织构深度,使得弹性织构摩擦副的摩擦力最小且承载力最大;适当增大滑动速度以及织构间距可以提高弹性摩擦副的润滑性能;随着弹性模量的降低,弹性变形和油膜厚度增加,空化现象更为显著,摩擦副的润滑性能得到提升。     

Performance of cutting tools with dimple textured surfaces: A comparative study of different texture patterns

Recently, surface texturing has received much attention as a method of enhancing the tribological properties of a cutting tool surface. However, effective texture patterns and dimensions on a tool surface are still difficult to obtain and suitable textures can be obtained only by trial and error. In order to overcome this problem, we newly develop cutting tools with dimple-shaped textures having different dimensions and arrays, generated on the tool rake face. In addition, we evaluate their crater wear resistance and cutting forces in steel material cutting. Furthermore, under various cutting conditions, the performances of the cutting tools with dimple-shaped textures are compared with those of tools with groove-shaped textures in order to establish a guideline for designing appropriate surface textures on cutting tool surfaces. A series of cutting experiments demonstrate that the dimple textures significantly improve the crater wear resistance and the tribological behavior on the tool rake face, and they exhibit a superior performance compared with those with groove textures, especially in a severely lubricated environment.     

双辉光离子渗铜对缸套-活塞环摩擦学性能的影响*

为研究铜元素对缸套-活塞环摩擦学性能的影响,通过双辉光离子渗透技术在缸套材料表面加工出不同厚度的渗铜改性层,使用RTEC多功能摩擦磨损试验机开展不同负载、不同润滑条件下的模拟试验,采集并分析试验过程中的摩擦因数以及试验后体积磨损量和磨损表面形貌,研究渗铜改性层对缸套材料摩擦学性能的影响规律及作用机制。结果表明：渗铜处理可有效降低缸套-活塞环摩擦副的摩擦因数,减少磨损量;高载荷和干摩擦条件下渗铜改性层的减摩抗磨作用效果尤为显著,最高可使摩擦因数分别降低13.15%和30.86%,磨损量分别降低30.70%和38.57%;渗铜后缸套-活塞环磨损表面形貌平整,摩擦表面形成了铜含量较高的润滑膜层,该表面膜起到了减摩、耐磨的作用。     

计入粗糙度的液压缸仿生微织构耦合效应研究

在间隙密封液压缸缸筒的内表面构造仿生菱形微织构,研究计入液压缸摩擦副表面粗糙度与表面微织构对液压缸缸筒内表面摩擦润滑性能的耦合影响。利用等效流量法求解表面微织构与表面粗糙度的耦合效应,同时以液压缸常用材料45钢为试件开展摩擦学试验,并对试验结果和仿真结果进行比较。研究结果表明:液压缸摩擦副的表面粗糙度与表面微织构耦合作用非常明显,合适的表面粗糙度和表面微织构尺寸,可使液压缸缸筒内表面从混合润滑状态转变为流体润滑状态,从而增大缸筒内表面的动压润滑效应;缸筒内表面的菱形微织构形貌存在最优组合,使得液压缸缸筒内表面的摩擦因数最小、润滑性能最好。     

基于 STFT 的织构涂层硬质合金表面振动解析方法

针对织构涂层复合工艺对硬质合金表面改性时存在消极振动的问题,提出一种基于织构涂层表面摩擦振动行为的解析 方法来探索织构涂层复合工艺改性效果。 因此,搭建了微织构 AlSiTiN 涂层硬质合金-钛合金磨盘摩擦磨损试验平台,基于短 时傅里叶变换(STFT)与灰度算法对摩擦振动变化规律性映射和振动行为平稳时段进行了获取,进而分析了微织构 AlSiTiN 涂 层工艺参数对硬质合金的改性效果。 试验研究得出了微织构及 AlSiTiN 涂层对硬质合金表面耐磨改性效果最为积极的时间 段,即自接触摩擦起第 5~ 25 min 的稳定作用时期,得出微织构及 AlSiTiN 涂层参数对硬质合金表面改性的影响机理,优选该复 合改性方法抑制硬质合金表面消极摩擦振动的工艺参数,为提升硬质合金表面性能研究提供新思路。     

基于椭圆织构优化的间隙密封液压缸摩擦性能研究

考虑织构参数对零件表面性能影响的多变性和复杂性,以间隙密封液压缸为研究对象,在液压缸的缸筒内壁构造椭圆微织构形貌,采用循环迭代法研究椭圆织构的长短轴比、椭圆率以及面积占有率等多个椭圆形状参数同时变化对缸筒表面动压润滑和摩擦性能的影响;同时在获得最优椭圆织构参数后进一步分析了液压缸与活塞间隙以及活塞运动速度对织构表面摩擦特性的影响。结果表明此种方法可以得到最优椭圆织构参数即优势区间,即当椭圆织构的长、短轴尺寸分别为a∈［0.43,0.46］mm,b∈［0.29,0.32］mm,缸筒表面产生最大动压和最佳润滑特性,且存在一个最佳间隙值(2 μm)使得织构表面油膜承载力最大,而活塞运动速度对缸筒表面的摩擦性能影响较小。     

Texture shape effects on hydrodynamic journal bearing performances using mass-conserving numerical approach

ABSTRACT

It is a known fact that incorporating textures in the contact surfaces can significantly enhance bearing performances. The purpose of this paper is to outline the effects of texture bottom profiles and contour geometries on the performances of hydrodynamic textured journal bearings. The analysis was conducted using computational approach to test eight texture shapes: rectangular, cylindrical, spherical, triangular (TR, T1, T2, T3) and chevron. The steady-state Reynolds equation for modelling the hydrodynamic behaviour of thin viscous film was solved using finite difference technique and mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. The comparison with the benchmark data shows good consistency and an enhancement in bearing performances (load carrying capacity and friction). The results clearly show that the mechanisms of wedge effect and micro-step bearing for the full/partial texturing feature are the main crucial parameters, where the convergent wedge effect present in T2 triangular texture shape can significantly enhance the load-carrying capacity, while the divergent wedge action causes a net load loss. Considering the right arrangement of textures on the contact surface, their surface contours can have a significant impact on the performance of hydrodynamic journal bearings at high eccentricity ratios.     

Experimental assessment of textured tools with nano-lubricants in orthogonal cutting of titanium alloy

In this study, we investigated the effects of composite nano-Cu/WS₂ lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS₂ lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS₂ lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.

     

Tribological Properties of Lubricating Films on the Al-Si Alloy Surface via Laser Surface Texturing

Dimpled textures were prepared by using a pulse solid laser on the surface of Al-Si alloy. The combination of laser surface texturing (LST) and MoS₂ solid lubricant as well as their tribological properties were investigated in this article. The obtained friction and wear data were critically analyzed to investigate how the parameters of texture influence the tribological performance of Al-Si alloy. Furthermore, morphological investigations of the transfer layers on the worn surfaces were performed and the wear mechanisms are discussed. The results show that the combination of LST and solid lubricant improves the tribological characteristics of Al-Si alloy. The friction coefficient of Al-Si alloy: steel friction pairs can be reduced to 0.15 under dry friction. The lubrication mechanism is attributed to a synergetic effect of providing solid lubricant and traps wear debris in the dimples. It was found that the optimum density of structure was 37% for excellent tribological properties.     

人工髋关节织构化表面摩擦学性能研究

为研究微织构形状对人工髋关节表面摩擦特性的影响,在人工髋关节表面分别设计仿生菱形织构、圆柱形织构和圆环形织构,以雷诺方程为理论研究基础建立流体动压润滑模型,用ANSYS Fluent进行数值模拟,得到微织构表面润滑油膜的平均承载力和摩擦因数,并比较不同织构形状的摩擦学性能。结果表明：在所选织构参数、工况参数范围内,平均承载力随着面积率增大以及滑动速度的提高均呈现上升趋势,在面积率为25%、滑动速度为0.3 m/s时达到最大;摩擦因数随着织构面积率的增大而呈下降趋势,在面积率25%达到最小值,摩擦因数与滑动速度的关系则因织构形状的不同存在一定的差异;研究的3种形状微织构中,仿生菱形织构的摩擦学性能最佳。因此合理选择织构形状可以减少人工髋关节摩擦副表面间的磨损。