基础油粘度对磨损自补偿性影响研究

本文对两种载荷下钢－铜摩擦副在不同粘度的润滑介质（其中包括含有和未含自补偿剂ＳＷ４）作用下的摩擦学特性进行了研究。发现自补偿添加剂ＳＷ４与常规润滑添加剂不同,基础油粘度越低,载荷越大,钢－铜摩擦副的磨损越上,其磨损自补偿性能越好,自补偿添加剂ＳＷ４为油品的低粘化提供了一条有效途径     

自补偿摩擦表面微观形貌分析

进行了钢－铜摩擦副的原始表面、常规润滑油和自补偿滑油润滑下的表面微观形貌测试和分析;对自补偿润滑下和常规润滑下钢、铜表面的粗糙度和表面轮廓特征参数进行了比较;研究了载荷、摩擦行程对自补偿润滑下钢、铜表面微观形貌的影响;得出了钢－铜摩擦副的磨损在一定范围内与载荷无关、其磨损不随摩擦行程线性增加、自补偿添加剂ＳＷ４更适应于重载工况和经过大的摩擦行程后仍起作用等结论。     

直链脂肪酸与直链脂肪醇混合对钢—钢和钢—铝摩擦副摩擦磨损性能的影响研究

本文利用四球摩擦磨损试验机和SRV摩擦磨损试验机研究了直链脂肪酸和直链脂肪醇以及其混合物对钢－钢、钢－铝摩擦副的摩擦磨损性能的影响。结果表明，对钢－钢和钢－铝摩擦副的润滑，直链脂肪酸和直链脂肪醇混合物的抗磨性能要优于单独的直链脂肪酸和直链脂肪醇的抗磨性能。     

磨损自补偿的载荷效应研究

通过载荷对磨损自补偿添加剂的性能的影响研究,发现在磨损自补偿添加剂ＳＷ４的作用下,钢－铜摩擦副的磨损量与载荷无关;而且载荷越大,钢－铜摩擦副的磨损自补偿效应越显著,这些结果不同于传统的摩擦学理论。因此。磨损自补偿添加剂ＳＷ４特别适合于重载工况下运行的钢－铜摩擦副,如轧钢厂压下系统的丝杆－螺母副,为提高这类重载钢－铜摩擦副的寿命和可靠性提供了一条有效途径。     

铜对钢摩擦条件下润滑油和极压抗磨剂的抗磨性考察

一般钢对钢摩擦的模拟试验机不能正确反映铜对钢摩擦副的摩擦特性。本文提出了一种简便的铜对钢四球机测试方法，可测出铜磨损值，并对不同粘度的基础油和常用极压抗磨剂作了Ｆｅ－Ｆｅ和Ｃｕ－Ｆｅ的摩擦特性对比。     

自补偿添加剂作用下钢-钢摩擦副的摩擦学特性

在轧机压下装置中的齿轮传动钢-钢摩擦副上,考察了所研制的磨损自补偿添加剂SW4对润滑油承载能力及钢-钢摩擦副摩擦磨损特性的影响。结果表明:磨损自补偿剂SW4加入所试验的4种润滑油中,都不同程度地提高钢-钢摩擦副的最大无卡咬负荷和烧结负荷,其中最大无卡咬负荷提高程度较大;同时钢-钢摩擦副的耐磨性也有很大的提高。     

供油温度对45^#淬火钢滑动摩擦副咬死影响的设计研究

在ＭＨＫ－５００型环块式磨损试验机上，在Ｌ－ＡＮ４６全损耗系统用油的不同供油温度下，对由４５＾＃淬火钢试环、试块组成的滑动摩擦副进行了抗咬死性能试验研究。试验结果表明：供油温度对摩擦副的抗咬死性能有较大的影响。在一定的范围内，提高润滑油的供油温度，有利于提高摩擦副的抗咬死能力。试验还发现：摩擦副失效后表面温度表现出不确定性。润滑油中的磨粒状况对摩擦副咬死影响不可忽视。对摩擦副咬死的研究应考虑润滑油     

冠醚化合物对钢/铜和钢/铝摩擦副的抗磨减摩性能研究

本文利用ＳＲＶ摩擦磨损试验机研究了省代苯并－１５－冠醚对钢／铜、钢／铝摩擦副的摩擦磨损性能的影响。结果表明,溴代苯并－１５－冠－５冠醚对钢／铜摩擦副起到减摩抗磨作用,对钢／铝摩擦副起到加速腐蚀磨损的作用。利用ＸＰＳ对磨痕表面进行了分析,发现铜和铝磨痕上发现了Ｂｒ,金属溴化物的生成减少了铜的摩擦和磨损,但却由于腐蚀而加速了铝合金的磨损。     

供油温度对 45~# 淬火钢滑动摩擦副咬死影响的试验研究

在ＭＨＫ－５００型环块式磨损试验机上，在Ｌ－ＡＮ４６全损耗系统用油的不同供油温度下，对由４５＃淬火钢试环、试块组成的滑动摩擦副进行了抗咬死性能试验研究。试验结果表明：供油温度对摩擦副的抗咬死性能有较大的影响。在一定的范围内，提高润滑油的供油温度，有利于提高摩擦副的抗咬死能力。试验还发现：摩擦副失效后表面温度表现出不确定性。润滑油中的磨粒状况对摩擦副咬死影响不可忽视。对摩擦副咬死的研究应考虑润滑油中磨粒随时间改变的因素，基于时变的观点来研究摩擦副咬死机理更具有实际意义。     

几种纳米润滑剂的摩擦学特性

采用超速粉碎工艺结合抗凝聚技术研制了三种不溶于水的纳米润滑添加剂：二硫化钼（MoS2）、聚四氟乙烯（PTFE）和滑石粉（talcum）。配方侧重考察了这些纳米级固体润滑剂的摩擦学特性，尤其是针对铜－钢摩擦副的摩擦磨损特性。结果发现在铜－钢摩擦副条件下，纳米级PTFE及滑石粉具有较好的抗铜磨损和降低摩擦系数的减摩性能；含硫的添加剂（包括MoS2）反而对铜引起不良摩擦的润滑作用。     

黄铜全流量在线磨粒静电监测实验研究

为深入了解静电监测方法对黄铜的监测能力,采用自制的全流量在线磨粒静电传感器开展黄铜的静电监测方法研究。研究了润滑条件下轴承钢-黄铜滑动摩擦荷电磨粒的产生机理并设计了磨粒静电监测系统,开展了三种尺寸的轴承钢球和黄铜球的单颗粒注入实验、双颗粒注入实验以及相同载荷、不同滑动速度的轴承钢-黄铜滑动摩擦磨损实验,对摩擦因数、静电感应信号、静电信号均方根值进行相关性分析。研究结果表明:全流量在线磨粒静电传感器具有较好的检测一致性;静电监测方法对黄铜的监测能力强于对轴承钢的监测能力;摩擦因数与静电监测信号具有相关性,在磨损阶段,静电感应信号出现脉冲尖峰与持续上升。     

钢衬铜管在空调产品上的使用工艺性研究

空调行业竞争日益激烈,各空调企业一直在寻求价格低廉、质量可靠的铜管替代品,钢衬铜管具有较好的焊接性能和不错的抗氧化能力得到关注.通过对钢衬铜管和铜管理化性能以及机械性能进行对比试验,对钢衬铜管与铜管的焊接工艺性和加工工艺性进行研究,以期确认钢衬铜管使用在空调产品上可行性.     

材料摩擦因数的可控性研究

在边界润滑状态下采用轴承钢、黄铜等不同摩擦副材料，对一些通用和特殊润滑材料在外加电场作用下摩擦因数的变化进行试验研究，探讨了它们的摩擦控制性能。结果表明：尽管外加电场都能改变这些润滑剂的摩擦因数，但只有BH－1型铁磁流体具有比较理想的摩擦控制性能，说明摩擦可控性并不是润滑材料普遍具有的性质。     

Electrode wear and material removal rate during EDM of aluminum and mild steel using copper and brass electrodes

In the present study an analysis has been done to evaluate the electrode wear along the cross-section of an electrode compared to the same along its length during EDM of aluminum and mild steel using copper and brass electrodes. In an overall performance comparison of copper and brass electrodes, we found that electrode wear increases with an increase in both current and voltage, but wear along the cross-section of the electrode is more compared to the same along its length. This is due to easier heat transfer along the length compared to the same along the cross-section of the electrode. It was also found that the wear ratio increases with an increase in current. That means, though a higher current causes more removal of work material and the electrode, comparatively more material is removed from the electrode. The highest wear ratio was found during machining of steel using a brass electrode. The low thermal conductivity of brass electrodes causes less heat loss, and its low melting point results in fast melting of the electrode material. At the same time, low thermal conductivity of steel results in poor heat absorption, and its high melting temperature causes poor removal of work material. These factors result in the highest wear ratio during machining of steel using a brass electrode. The highest material removal rate was observed during machining of aluminum using brass electrodes. Comparatively low thermal conductivity of brass as an electrode material does not allow the absorption of much heat energy, and most of the heat is utilized in the removal of material from aluminum workpiece at a low melting point. But during machining of steel using copper electrodes, a comparatively smaller quantity of heat is absorbed by the work material due to its low thermal conductivity. As a result material removal rate becomes very low.     

Scanning electron microscopy observations of worn surfaces of metals in tribological contact with loose solid particles

Surfaces of a 40–60 brass worn by three-body abrasion with SiC grits were observed under the scanning electron microscope. Similar observations were carried out on targets of steel and commercially pure aluminium which had been impacted with hardened steel balls. The brass develops alternating bands of hills and valleys when undergoing three-body abrasion. The hills wear by direct rubbing against the steel counterface. The valleys, however, are embedded with grits which are later removed and probably carry an amount of brass during their departure. The impact process creates craters which show severe deformation. Radial plastic flow of metal also occurs in the target around a crater. It appears that under repeated attack these deformed areas produce wear debris by microspalling. Metal may also be removed by nucleation and propagation of cracks.     

Ultrasonic machining of engine lubricating oil during tribotechnical testing

The results of tribotechnical testing of brass–steel and iron–steel friction couples for both their running-in ability and wear resistance have been described. For brass and iron jaws of friction couples, it has been established that the load before tearing increased to 4.3 and 12.3%, respectively, in synthetic oil, while for semisynthetic oil, it increased to 12.5 and 25.0%. It has also been found that ultrasonic machining enabled a decrease in the coefficient of friction for brass and iron jaws in synthetic oil to 13.4 and 15.3%, respectively, and 25.0 and 28.1% in semisynthetic oil. Any features of the residual viscosity of engine lubricating oil after ultrasonic machining, which cannot be measured with a fluidmeter, have been found.     

Note: Development of target changeable palm-top pyroelectric x-ray tube

A target changeable palm-top size x-ray tube was realized using pyroelectric crystal and detachable vacuum flanges. The target metals can be exchanged easily by attaching them on the brass stage with carbon tape. When silver and titanium palates (area: 10 mm(2)) were used as targets, silver Lα and titanium K lines were clearly observed by bombarding electrons on the targets for 90 s. The intensities were the same or higher than those of previously reported pyroelectric x-ray tubes. Chromium, iron, nickel, copper, and zinc K lines in the x-ray tube (stainless steel and brass) disappeared by replacing the brass stage and the stainless steel vacuum flange with a carbon stage and a glass tube, respectively.     

Note on contributors

The influence of an external d.c. magnetic field on the diffusive wear of two rubbing bodies represented by idealized asperities was investigated. The magnetic field affects the fracture characteristics at the asperity junction giving different wear rates owing to the presence of the magnetic field. A simple model predicts how the hardness gradient at the surface of the asperity is of significance in affecting the wear characteristics of a sliding pair. The mass of a wear particle is directly affected by diffusivity, and the application of an external magnetic field to a deforming junction affects it considerably. Numerical calculations and experimental observations for mild steel rubbing against brass support the predictions that the application of an external magnetic field enhances diffusive wear at an asperity junction.     

Signature Response for Friction and Wear

An experimental study of signature response for friction and wear is carried out in a triplane ball-on-peg machine under varying load conditions. Photographs of worn roller test specimens at critical temperatures were taken to determine the nature of the wear surface under boundary lubricated conditions. Acoustic response in the beginning and at the point of scuffing has demonstrated a definite trend which follows a similar pattern as that of friction. The experiment was repeated with a combination of steel and brass and with steel and mild steel using as the lubricants hexadecane, MoS₂ and light stock oil. The scuffing load was accompanied by severe wear of the surface. A critical value for friction and that of acoustic response was observed with variations in temperature. Results obtained contribute to the assesment in the change in friction and wear values on sliding surfaces. This help comes from a knowledge of acoustic emission and the known condition of the surface and both components of the pair. The findings of these experimental results and the mode of signature response provides a good scope for further investigations aimed at understanding the mechanism and establishing a method for diagnostic maintenance.     

Cavitation erosion in a dilute emulsion

The cavitation erosion of mild steel, brass, and pure iron in emulsions made with distilled water and 1.0% NaCl solution was investigated using a vibratory apparatus operating at 20 kHz and 15 μm amplitude. The emulsion reduced the steady-state erosion rate of mild steel in distilled and salt water to about 80% and 30%, respectively, of the values for no emulsion, but had no effect on brass in distilled water. Changes in the microstructures of the eroded surfaces and in the pH of the solution are presented and discussed in relation to the erosion curves.