磁流变效应微砂轮的磨粒半固着机理研究

针对磁流变效应微砂轮抛光工艺,理论分析了磁流变效应磁链对磨粒的有效约束使磨粒处于半固着状态的机理。建立了磨粒受磁链约束的模型,研究了磁流变工作液中磨粒的种类、大小、形状和体积分数等特性对磨粒半固着状态以及所形成的磁流变效应微砂轮性能的影响。进行了磁流变效应微砂轮加工沟槽实验,分析了磨粒特性对材料去除率的影响,实验结果与理论分析相吻合,表明所建立的磁流变效应微砂轮磨粒半固着理论是正确的。     

基于分形理论的磨粒磨损模型

本文在M-B接触分形模型的基础上,根据塑变磨损理论导出了基于分形参数的磨粒磨损模型,建立了磨损率与分形维数之间的关系,综合反映了材料的磨损规律和表面特性。根据该模型可知,当分形维数在某一范围时,磨损率随分形维数的减小而迅速增大;而在另一范围时,磨损率随分形维数的增大而增大;当分形维数等于1.5时,磨损率达到最小值。当分形维数一定时,磨损率随尺度系数、磨损概率常数的增大而增大,随材料性能参数的增大而减小;当其余各影响参数保持一定值时,磨损率随接触面积的增大而增大。     

基于分形理论的磨粒磨损类型

本文在M-R接触分形模型的基础上，根据塑变磨损理论导出了基于分形参数的磨粒磨损模型，建立了磨损率与分形维数之间的关系，综合反映了材料的磨损规律和表面特性。根据该模型可知，当分形维数在某一范围时，磨损率达到最小值。当分形维数一定时，磨损率随尺度系数、磨损概率常数的增大而增大。随材料性能参数的增大而减小；当其余各影响参数保持一定时，磨损率随接触面积的增大而增大。     

磨粒磨损的模型化分析

磨粒磨损作为磨损的主要类型之一,影响机械使用寿命。针对犁沟磨损机制,用球形、圆锥形和圆台形磨粒模型分析其磨粒磨损的磨损率和摩擦因数,考虑磨粒数量与磨粒尺寸间的指数关系,分析磨损率随磨粒数量和磨粒尺寸的变化,计算平均摩擦因数随磨粒数量及其参数的变化。研究结果表明,球形磨粒模型的磨损率随着磨粒的减小和磨粒数量的增加而减小,其摩擦因数随着磨粒数量的增多而增大;圆锥形磨粒模型的磨损率随着磨粒的增大与数量的增多而增大,其摩擦因数随着倾斜角的增大而增大;圆台形磨粒模型的磨损率变化趋势与球形磨粒一致,但其摩擦因数变化的趋势与球形磨粒相反。     

氧化铝颗粒增强铜基复合材料的摩擦磨损性能

利用粉末冶金法制备了Al_2O_3颗粒增强铜基复合材料,分析了Al_2O_3含量和转速对复合材料耐磨性能以及摩擦因数的影响。结果表明:复合材料的磨损量随Al_2O_3含量的增加先减小后增大,Al_2O_3体积分数为15%时耐磨性能最好;磨损量以及摩擦因数随着转速的增大先增大后减小,在400 r·min~(-1)时的磨损最严重,摩擦因数最大;磨损主要机制是粘着磨损和磨粒磨损。     

机械密封端面黏着磨损分形模型

在机械密封端面接触分形模型基础上,依据Archard磨损理论,通过引入分形磨损系数及求解塑性和弹塑性变形微凸体的体积,建立了机械密封端面黏着磨损分形模型。得到了机械密封软质环端面磨损率与端面轮廓分形参数、真实接触面积、材料性能参数以及工作参数之间的关系式。对B104a-70型机械密封软质环端面的磨损率进行了计算和分析。结果表明,端面磨损率随着端面比压、转速及端面特征尺度系数的增大而增大;随着端面分形维数的增大先迅速减小后逐渐增大,即存在一个使磨损率最小的最优分形维数。     

集群磁流变变间隙动压平坦化加工试验研究

为了提高光电晶片集群磁流变平坦化加工效果,提出集群磁流变变间隙动压平坦化加工方法,探究各工艺参数对加工效果的影响规律。以蓝宝石晶片为研究对象开展了集群磁流变变间隙动压平坦化加工和集群磁流变抛光对比试验,通过检测加工表面粗糙度、材料去除率,观测加工表面形貌、集群磁流变抛光垫中磁链串受动态挤压前后形态变化,研究挤压幅值、工件盘转速、挤压频率以及最小加工间隙等工艺参数对加工效果的影响规律。试验结果表明：集群磁流变平坦化加工在施加工件轴向微幅低频振动后,集群磁流变抛光垫中形成的磁链串更粗壮,不但使其沿工件的径向流动实现磨粒动态更新、促使加工界面内有效磨粒数增多,而且在工件与抛光盘之间的加工间隙产生动态抛光压力、使磨粒与加工表面划擦过程柔和微量化,形成了提高材料去除效率、降低加工表面粗糙度的机制。对于2英寸蓝宝石晶电（1英寸=2.54 cm）集群磁流变变间隙动压平坦化加工与集群磁流变抛光加工效果相比,材料去除率提高19.5%,表面粗糙度降低了42.96%,在挤压振动频率1 Hz、最小加工间隙1 mm、挤压幅值0.5 mm、工件盘转速500 r/min的工艺参数下进行抛光可获得表面粗糙度为Ra0.45 nm的超光滑表面,材料去除率达到3.28 nm/min。证明了集群磁流变变间隙动压平坦化加工方法可行有效。     

动磁场磁流变效应抛光垫抛光力特性试验研究

基于动磁场磁流变效应抛光方法,采用微型压电式传感器测试分析动磁场磁流变效应抛光垫法向抛光力特性,研究磁极转速、加工间隙、工件运动方式对动磁场磁流变效应抛光力的影响。结果表明,动磁场磁流变效应平面抛光法向力在抛光垫中心区域最大,pv值在抛光垫的半径6 mm处最大;相对静磁场,在磁极转动的动磁场作用下磁流变抛光力和扭矩呈现大幅度波动的动态行为;动磁场磁流变效应抛光力受到磁极转速影响,大于15 r/min开始产生动磁场,在试验所测得的范围内,磁极转速30 r/min左右有最好效果;工件运动方式是影响磁流变抛光作用力的因素,当工件沿抛光盘径向往复偏摆时扭矩剧烈变化,沿抛光盘法向运动加工间隙减小时抛光法向力会瞬间急剧增大,最大峰值达到稳态值的25倍。     

钎焊金刚石薄壁钻钻磨氮化硅陶瓷的磨损研究

采用钎焊金刚石薄壁钻进行钻磨氮化硅陶瓷的试验,研究了金刚石粒度、壁厚、主轴转速和钻压对钻头寿命的影响。同时,研究了钎焊金刚石薄壁钻的磨损形态,包括金刚石磨粒磨损和粘结剂磨损。结果表明,钻头寿命随金刚石粒度和壁厚的增大而减小,随主轴转速和钻压的增大而先增大后减小;金刚石磨粒的磨损形态包括磨粒磨平、破碎及脱落,且以磨平为主,脱落较少;粘结剂磨损主要包括粘结剂断裂与流沙形态磨损。     

磨粒对ADZ复合陶瓷材料磨损性能的影响

采用块 -块摩擦磨损试验机在不同磨粒的 5 %NaOH泥浆中 ,对氧化铝增强四方氧化锆多晶陶瓷材料 (ADZ)的磨损性能进行了研究。研究结果表明尖锐磨粒对ADZ复合陶瓷材料磨损的影响要比球形磨粒严重的多 ,磨料硬度是影响陶瓷材料磨损率的重要因素 ,磨损率随磨粒硬度的提高而增大。在不同形状的SiO2 磨粒的泥浆中ADZ陶瓷材料的主要磨损机理为塑性变形和微犁削。在高硬度Al2 O3磨料的泥浆中ADZ陶瓷材料磨损表面以断裂机制占主导地位。     

GCr15微动磨损转向往复滑动磨损特性的研究

对GCr15金属球和平面试块在300N的法向力作用下作了从微动磨损向往复滑动磨损转变的试验研究，对摩擦磨损过程中的磨损系数、摩擦力变化特性、磨痕的轮廓进行了分析研究。结果表明，在微动磨同往复滑动磨损转变前后，除磨损系数出现突变外，摩擦系数和磨痕的轮廓形貌也发生了比较大的变化，磨损转变过渡区的范围为70－100μm。     

深井、超深井套管磨损机理及预测技术研究

概述了近年来深井、超深井套管磨损机理及预测技术的研究动态，讨论了套管磨损主导机理及其影响因素的几种观点，重点分析了磨损效率模型的特点，明确了深井、超深井套管磨损研究的主要发展方向。     

Characterization of wear scar surfaces using combined three-dimensional topographic analysis and contact resistance measurements

In this paper, a technique for the quantitative characterization of wear scar surfaces, using combined three-dimensional topographical analysis and contact resistance measurements, is introduced. Parameters for the characterization of wear surfaces, developed during sliding of pin-on-disk specimens in oxygen at high temperature, such as wear volume, roughness, average wear depth on the disk specimen, surface coverage by wear-protective oxide layers and their distributions over the wear surface, are presented and calculated. Such analyses provide more effective data for the analysis of wear processes and wear mechanisms.This method has been applied to the analysis of dry reciprocating sliding wear of a nickel-base alloy, N80A, at temperatures to 600°C. It was found that there was usually a difference between the wear rates of the pin and the disk. This difference increased with increase in temperature, the wear of the pin being much less than that of the disk at the higher temperatures. Although the total wear of both the pin and the disk decreased considerably with increase in temperature, the damage to the disk, judged by the wear depth of the scar, was much higher at elevated temperatures than at low temperatures. The roughnesses of the wear surfaces generally increased with increase in temperature. Less than 50% coverage of the scar surfaces by wear-protective oxide layers was sufficient for the severe-to-mild wear transition. However, the distribution of the wear-protective layers over the wear surfaces was non-uniform. Most of them were concentrated near the centre of the scar, along the sliding direction, under the present conditions. These features of the wear scar surfaces were mainly related to the adhesion and compaction of wear debris particles onto the wear surfaces, leading to development of the wear-protective layers at the various temperatures.     

A Finite Element Approach to Modeling Abrasive Wear Modes

Machine components operating in sandy environments will wear because of the abrasive interaction with sand particles. In this work, a method is derived to predict the amount of wear caused by such abrasive action, in order to improve the maintenance concept of the components. A finite element model is used to simulate various tips scratching a smooth surface. The model is verified by comparing the obtained results with a set of experiments performed earlier (M. Woldman, et al., 2013, Wear, 301(1–2), pp 76–81).     

陶瓷材料磨损机制及磨损程度评价方法综述

综合分析陶瓷材料摩擦磨损的机制和影响摩擦磨损的各种因素,如表面加工状况、载荷、速度、时间、温度、润滑等。介绍几种陶瓷材料摩擦磨损程度的评定方法,如用量纲一化参数(最大赫兹接触压力、最大表面粗糙度和断裂韧性的函数Sc,硬度、最大表面粗糙度和断裂韧性的函数S*)大小评价磨损程度,用磨损表面的粗糙度Ry与平均粒径Dg的比值评价陶瓷材料磨损程度,用磨损率评价陶瓷材料磨损程度等。以期指导人们进一步认识陶瓷摩擦磨损的本质规律,有目的地调整材料的性能以提高其耐磨性。     

Wear prediction for metals

In spite of the large number of wear models found in the literature, no model can predict metal wear a priori based only on materials property data and contact information. The complexity of wear and the large number of parameters affecting the outcome are the primary reasons for this situation. This paper summarizes the current understanding of wear modelling for metals. Several recent approaches such as wear mapping and wear transition diagrams have suggested some future possible directions for improvement. Some success has been achieved in describing severe wear of steels under unlubricated conditions using thermomechanical approaches. However, modelling of mild wear remains problematic, especially under lubricated conditions. In mild wear, asperity contact events dominate the wear processes. A single asperity collision simulation apparatus has been used to study asperity-asperity contact phenomena. Shear strain and strain accumulation were found to be the dominant underlying causes for wear. It is proposed that future research in wear prediction for metals incorporate the following aspects: wear mapping, temperature, shear strain response, boundary lubricating film strength, and surface roughness.     

Wear reducing effects and temperature dependence of tribolayer formation in harsh environment

Certain materials show a tribolayer formation especially at enhanced temperatures in abrasive environment, building a wear protection layer with the abrasive on the surface. Three materials with different microstructures were tested in three-body abrasive and impact/abrasive environments at temperatures up to 700 °C to investigate tribolayer formation. Optical and electron microscopical methods were used for wear qualification. Furthermore, hot hardness tests were performed up to 700 °C to investigate the influence of hardness drop on tribolayer formation.It was shown that no significant tribolayer formation occurs on grey cast iron, whereas other materials form tribolayers. Generally, tribolayer formation increases with increasing testing temperature, especially for austenitic and ferritic materials. This entails a self-protecting effect and thus superior wear resistance in abrasive environment.     

ZTA陶瓷刀具连续切削淬硬T10A时的切削性能研究

研究两种自主研制的新型ZTA(Al2O3/Zr O2)陶瓷刀具切削淬硬T10A时的切削性能。刀具后刀面磨损量随切削深度和切削速度的增加而增大;刀具的主要磨损形态为后刀面磨损;主要磨损机理为后刀面磨粒磨损和部分粘结磨损。     

Fretting Wear Behavior of UHMWPE—Influence of Load and Stroke

In this study, the tribological behavior of ultra-high-molecular-weight polyethylene (UHMWPE) against a GCr 15 steel ball during fretting wear conditions was investigated using an oscillating reciprocating tribometer. The aim of this study was to characterize the critical value of normal load and stroke corresponding to this transition in UHMWPE worn surface at room temperature. Results showed that there existed a critical value of load or stroke at fixed condition. The friction coefficient and wear volume loss of UHMWPE at or near the critical values of load and stroke exhibited extreme changes. Based on observation of the worn surface by scanning electron microscopy (SEM) and 3D surface profiler measurements, it can be found that damage to the worn surface can be linked to the contact load and stroke. In addition, results showed that during the process of fretting wear under different load or stroke conditions, the gross slip regime dominated throughout the whole test period.     

Microstructure and Wear Behaviors of Plasma-Sprayed FeCrNiMoCBSi Coating with Nano-Grain Dispersed Amorphous Phase in Reciprocating Sliding Contact

A novel FeCrNiMoCBSi amorphous/nanocrystalline coating was fabricated using a plasma spraying process. The coating was dense with a low porosity of approximately 0.99%. The coating consisted of a 67.8 vol% amorphous phase coupled with many nanocrystalline grains that were approximately 5?nm in diameter. The mechanical properties of the as-sprayed coating were determined by nanoindentation measurement, and the tribological behaviors were systematically investigated in a reciprocating sliding contact. The results show that FeCrNiMoCBSi coatings possess superior wear resistance compared to other typically similar Fe-based amorphous coatings. The tribological behaviors evolve with the combination of normal load and sliding velocity. Herein, the dominant wear mechanisms are delamination wear and oxidation wear. With an increase in normal load and sliding velocity, the abrasive wear is gradually weakened, the formation of oxide films on the worn surfaces is facilitated, and wear debris is ground to powder. The oxide films suffer from fatigue wear with induced cracks undergoing reciprocating sliding effects.