Tribological properties of non‐ferrous coating lubricated with rapeseed oil containing lubricant additives

With the increasing requirements of environmental protection, using lead, hexavalent chromium and other heavy metals will be prohibited in different surface coatings. In this paper, the non‐ferrous CrN coatings and the rapeseed oil were chosen as friction pair and biodegradable lubricant. The tribology properties were investigated using SRV‐IV reciprocating friction wear test. The worn surface of CrN coatings was observed and analysed using scanning electron microscopy and X‐ray photoelectron spectroscopy. The results indicate that the rapeseed oil containing 1 wt.% MoZn (MoDTC (molybdenum dithiocarbamate) + ZnDTP (zinc dithiophosphate) (1 : 3)) exhibits better friction‐reducing properties than the rapeseed oil containing 1 wt.% PN (an amine salt of an alkoxylphosphate) additives, whereas the rapeseed oil containing 1 wt.% PN additive exhibits better wear resistance properties than the rapeseed oil containing 1 wt.% MoZn additives. This is partly attributed to the tribophysical and tribochemical reactions between the lubricant and the CrN coating sliding surfaces. Copyright © 2012 John Wiley & Sons, Ltd.     

Applicability of ring‐on‐disc and pin‐on‐plate test methods for Cu–steel and Al–steel systems for large area conformal contacts

This study compares two methods for model scale testing of ferrous/non‐ferrous tribocouples under large area conformal contact condition, the kind existing in engine components such as journal bearings. Results show that the ring‐on‐disc method is better suited to visualise the performance of such tribosystems compared with the pin‐on‐plate method. The former offers greater sensitivity to minor changes in coefficient of friction and contact potential and is able to determine the thermal stability of the tribosystem under given conditions. Post‐test surface characterisation revealed protective phosphorus‐rich tribofilms on the surface of the steel counterparts from both test methods. Copyright © 2012 John Wiley & Sons, Ltd.     

A high throughput inductive pulse sensor for online oil debris monitoring

A high throughput inductive pulse sensor based on inductive Coulter counting principle for detecting metallic wear debris in lubrication oil is presented. The device detects the passage of metallic debris by monitoring the inductance change of a two-layer planar coil with a meso-scale fluidic pipe crossing its center, which is designed to attain high throughput without sacrificing the sensitivity. The testing results using iron and copper particles ranging in size from 50 to 150 μm have demonstrated that the device is capable of detecting and distinguishing ferrous and non-ferrous metallic debris in lubrication oil with a high throughput.     

Synthesis and tribological properties of ferrous octoxyborate as antiwear and friction-reducing additive of lubricating oil

An oil-soluble compound containing ferrous iron and boron–ferrous octoxyborate was synthesized. The antiwear and friction-reducing properties of the compound as a lubricating oil additive were evaluated using a four-ball and a block-on-ring tribotester. Results indicated that both the wear resistance and the load-carrying capacity of a 500 SN base oil were improved and its friction coefficient was decreased by the additive. The wear scar, after being cleaned using an ultrasonic bath in ligroin and in distilled water, was characterized with SEM and XPS. Diboron trioxide, FeB and Fe₂B were all found to have been deposited on the wear-scar surface. It was this deposition that provided the oil with excellent antiwear and friction-reducing properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Non‐varnishing and tribological characteristics of polyalkylene glycol‐based synthetic turbine fluid

Varnish build‐up in heavy duty gas turbines is a leading cause of costly unplanned shutdowns and resulting lost power generation capacity. The culprit is the conventional petroleum‐based turbine oil, which breaks down to form varnish and sludge that cause servo valves to stick. Use of filtration to remove solid degradation by‐products addresses a symptom but not the root cause of varnish formation: the petroleum‐based turbine oils themselves. For the best protection against varnish‐related shutdowns, a switch from petroleum‐based turbine oil to non‐varnishing polyalkylene glycol (PAG)‐based synthetic turbine fluid was undertaken by four power plants in North America. PAG‐based synthetic turbine fluid chemistry, its tribological characteristics and successful trials in GE 7FA heavy duty gas turbines (General Electric Company, Fairfield, CT, USA) are discussed in this paper. PAG‐based synthetic turbine fluid has outperformed the hydrocarbon turbine oil in reduced sludge and varnish formation due to its polar nature and solvating power in plant trials as well as in a modified ASTM D 2893 test. Copyright © 2011 John Wiley & Sons, Ltd.     

Findings from a fleet test on the performance of two engine oil formulations in automotive CNG engines

This work presents a comparative assessment of engine oil performance on field test using urban transport vehicles powered by compressed natural gas engines using two different mineral oil formulations approved by engine manufacturer. The first one is considered as a baseline reference, and the second one is a higher quality formulation in terms of base stock refining and additive content. Higher quality oil has shown a significant enhanced lubricant performance, leading to reach the oil drain interval defined by engine manufacturer on these engines without penalties in maintenance costs. In order to assess oil performance, an oil analysis programme has been established for oil samples collected from vehicles operated under real service conditions in an urban transport fleet. Monitored parameters include oxidation, nitration, aminic anti‐oxidant additives depletion, anti‐wear additives depletion, total acid number, total basic number and remaining useful life number (as an estimation of anti‐oxidant additive depletion including aminic and zinc dialkyldithiophosphate). Results obtained in more than 90 samples from 15 different vehicles have shown higher degradation rates for low quality lubricant oil formulation. This deviation can be explained taking into account factors related with lower anti‐oxidant additives content and lower thermal stability that can be mainly related with the base stock quality. This lower oil performance can be finally converted into higher vehicle maintenance cost and lower engine reliability. Copyright © 2013 John Wiley & Sons, Ltd.     

Interaction of fomblin® lubricant with surface nitrided and/or coated bearing (M50) steel

High‐temperature perfluoropolalkylether lubricants including Fomblin^® are susceptible to degradation and cause corrosion in the presence of ferrous metals such as M50 bearing steel. This paper describes the effect of surface treatment (nitriding), coating chemistry and architecture in preventing corrosion/oxidation of M50 steel and thermo‐oxidative degradation of Fomblin^® fluid. Specifically, Cr‐CrN multilayered coating architecture was used with and without a nitrided steel surface. The oxidation/corrosion tests were conducted by immersing the nitrided and/or coated M50 coupons in Fomblin^® fluid in an oxidative environment at 270°C for 24 h and compared with untreated/uncoated coupons. It is shown that a considerable lessening of the corrosion of the steel and degradation of the Fomblin^® fluid can be achieved by nitriding alone. Nitriding in combination with the multilayered Cr‐CrN coating exhibited the best protection. The results are discussed in relation to the literature data. Copyright © 2009 John Wiley and Sons, Ltd.     

Improvement of thermooxidative stability of non‐edible vegetable oils of Indian origin for biodegradable lubricant application

For environmental reasons, as well as the dwindling source of petroleum, a new class of environmentally acceptable and renewable lubricants based on vegetable oils is available. Even though vegetable oils possess excellent lubricant‐related properties, there are some concerns about using it as lubricant base oil. Still, unmodified and modified varieties of soybean, rapeseed, sunflower and canola oils have been in use in the USA and Europe. In India, with the shortage of edible oil, alternate sources of vegetable oils stocks are being explored. With this aim, a comprehensive study has been conducted earlier in the authors' laboratory. In this study, numerous options of non‐edible vegetable oil sources were explored, and a few potential vegetable oils were studied in the laboratory. It was found that even though the oils performed much better in comparison with other vegetable oils, it still required improvement in thermooxidative stability. Therefore, in the later part of the study, different options were explored to improve thermooxidative stability. With a background on the initial studies of the authors as described above, the present paper deals with the studies on improvement of these non‐edible candidate vegetable oils of Indian origin for lubricant by treating with selected antioxidants for applying them in lubricants. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis of molybdenum polyisobutenyl succinate (MoPIBS) and a study of its tribological characteristics

In view of the increasing awareness of the need for environmental protection, it is considered important to have more low‐ or non‐phosphorus additives in engine oils. To this end, molybdenum polyisobutenyl succinate (MoPIBS) was synthesised and its structure investigated using spectroscopy. The antiwear and friction‐reducing behaviour of MoPIBS as an oil additive was investigated and compared to that of zinc dialkyldithio‐phosphate (ZnDDP) using a four‐ball tester. The results indicated that MoPIBS in white oil exhibits very good antiwear and friction‐reducing properties, better than those of ZnDDP, but that the load‐carrying capacity is poorer than that of ZnDDP. The worn surfaces were investigated using Auger electron spectroscopy (AES) and X‐ray photoelectron spectroscopy (XPS). It was found that the boundary lubrication film on the worn surfaces was mainly composed of MoO₃ and Fe₂O₃, which contributed to improving the tribological properties of MoPIBS as an additive in white oil.     

Physical and Tribological Properties Degradation of Silicone Rubber Using Jatropha Biolubricant

This article aims to investigate the degradation of physical and tribological properties (friction coefficients and wear resistance) of a dynamic sealing material (silicone rubber [VMQ]) exposed to Jatropha oil (JO), engine mineral oil (EMO), and a blend (B20; 80% EMO–20% JO), separately. JO has demonstrated better lubricating properties than EMO in various mechanical applications; however, the degradation of elastomers by using this oil has not been studied yet, nor have its effect on their tribological properties. The physical degradation was evaluated by conducting static immersion tests (670 h at 25 °C) based on ASTM-D471 and ASTM-D7216 methods. Hence, the changes in mass, volume, tensile and tear strengths, and hardness of VMQ were measured. In addition, creep compliance tests were conducted to determine the changes in viscoelastic properties and the changes in morphology and topography were measured by scanning electron microscopy (SEM) and optical profilometry, respectively. In addition, the compositional changes were determined by Fourier transform infrared (FTIR) analyses to complement the degradation examination. Changes in the friction coefficients were determined by ball-on-disk tests and changes in wear resistance were obtained by accelerated wear tests (microabrasion tests). Finally, VMQ exhibited no significant physical and compositional degradation due to immersion in the three lubricants. However, considerable changes in the friction coefficients and wear resistance were observed; the change in the friction coefficients was minimal using JO. In addition, the coefficients using JO were 50% lower than those for EMO and the changes in wear resistance were lowest after immersion in JO.     

Tribological degradation of two vegetable‐based lubricants at elevated temperatures

Renewable‐based lubricants are being considered as potential alternatives to petroleum‐based lubricants for various reasons, mainly increased environmental sensitivity. However, understanding the tribological performance of such vegetable‐based lubricants under elevated temperatures is critical for their industrial implementation. This study focuses on the friction and abrasion rate characteristics of soybean and sunflower base oils in comparison to a base mineral oil under sliding wear at elevated temperatures. It was found that the abrasion rate and friction were less severe for the vegetable‐based lubricants up to temperatures around 100°C. The observed performance of the vegetable‐based lubricants was verified using a kinetic reaction mechanism model of lubricant degradation. Copyright © 2007 John Wiley & Sons, Ltd.     

Property blending relationships for binary mixtures of mineral oil and elektrionised vegetable oil: viscosity,solvent power,and seal compatibility index

The present study provides quantitative data on the physicochemical properties of binary mixtures of a special class of bio‐based lubricity additives — elektrionised vegetable oils — with various classes of mineral base oils. A specific emphasis is placed upon viscosity blending relationships, solubility and seal compatibility. Experimental data are rationalised using appropriate theoretical models, which can be readily applied to property blending practice. It is shown that

• For elektrionised vegetable oil/mineral oil binary systems, viscosity blending calculations can be guided by using Roegiers or Grunberg–Nissan blending equations. The Roegiers equation works especially well for systems showing large deviation from ideal behaviour.
• Elektrionised vegetable oils can be used as mild solvency improvers for non‐conventional base oils produced by hydrocracking and isodewaxing technology or through gas‐to‐liquid conversion, Elektrion C (Elektrion s.a., Bruxelles, Belgium) being a more potent solvency improver than Elektrion R.
• Elektrionised vegetable oils demonstrate good seal compatibility in combination with various mineral basestocks. Copyright © 2011 John Wiley & Sons, Ltd.

     

滚动轴承性能退化静电监测方法及试验

采用静电方法对滚动轴承进行在线监测以及退化评估的研究。在滚动轴承寿命强化试验机平台上,使用自研磨损区域静电传感器对滚动轴承进行在线监测,通过多组试验采集得到滚动轴承磨损静电信号,在对滚动轴承磨损过程静电产生机理分析的基础上,进行静电信号的特征提取,通过加速疲劳全寿命周期试验进行滚动轴承性能退化评估,并与振动信号与温度信号进行对比验证。研究结果表明,磨损区域静电监测技术可以实现滚动轴承性能退化的在线监测,该研究是机械系统在线监测以及故障诊断和预测的重要组成部分,并为仪器实现产品化奠定了基础。     

A comparative experimental study on the diagnostic and prognostic capabilities of acoustics emission,vibration and spectrometric oil analysis for spur gears

Prognosis of gear life using the acoustic emission (AE) technique is relatively new in condition monitoring of rotating machinery. This paper describes an experimental investigation on spur gears in which natural pitting was allowed to occur. Throughout the test period, AE, vibration and spectrometric oil samples were monitored continuously in order to correlate and compare these techniques to natural life degradation of the gears. It was observed that based on the analysis of root mean square (rms) levels only the AE technique was more sensitive in detecting and monitoring pitting than either the vibration or spectrometric oil analysis (SOA) techniques. It is concluded that as AE exhibited a direct relationship with pitting progression, it offers the opportunity for prognosis.     

半合成极压切削液的研究与应用

半合成极压切削液是一种集乳化液和合成液优点于一体并具有良好极压性能的新一代切削液。按照微乳液调配理论,尤其利用HLB值方法,合理选择乳化剂、极压剂、防锈剂、润滑剂、稳定剂和杀菌防腐剂等多种添加剂并进行科学配伍。对产品进行理化性能测试、四球机承载能力试验、切削阻力试验等实验室评价和实际应用考察,研制了一种新型半合成极压切削液,广泛应用于数控机床、加工中心。     

Theoretical characteristics of hydrodynamic journal bearings lubricated with soybean‐based oil

Vegetable‐based oils are not only biodegradable but also environmentally advantageous, and the range of lubrication applications offered by them continues to grow. Recently, vegetable‐based oils have been combined with synthetic esters to produce modified vegetable‐based oils. This paper presents an investigation of the theoretical characteristics of hydrodynamic journal bearings lubricated with non‐Newtonian soybean‐based oil. The soybean‐based oil was mixed with synthetic esters and silicone oil. The relationship between the shear stress and shear strain rate of the oil was obtained experimentally. The time‐dependent modified Reynolds equation including non‐Newtonian effects was formulated for short circular journal bearings. The perturbation technique was applied to the Reynolds equation to obtain zero‐ and first‐order pressure equations. The finite difference method was used to calculate the pressure distribution numerically. The static and dynamic characteristics, such as pressure distribution, Sommerfeld number, attitude angle, and spring and damping coefficients, were obtained numerically. It was found that the nonlinear factors of the non‐Newtonian soybean‐based oil strongly affected the performance characteristics of the journal bearings.     

基于激光扫描的铁谱全谱定量分析系统研究

介绍了最新研制的一种基于激光扫描的铁谱全谱分析系统的工作原理、总体结构和应用实例。该系统利用旋转漏斗结合高梯度磁场制备磨屑的沉积谱片,依靠高精度激光传感器和自动检测装置实现铁谱片的全谱检测,并实时进行数据显示和计算机采集。利用故障诊断软件对全谱数据及其它指标数据进行综合分析,参考设备库和故障库,生成磨损监测和故障诊断报告。     

基于微螺线管电感式传感器的金属颗粒形态对输出特性影响的研究

基于电感测量技术与微流体技术的油液检测芯片, 不仅可以区分出铁磁性和非铁磁性金属颗粒, 还可以对油液中的颗粒进行计数统计和颗粒大小测量,从而判断金属颗粒污染物的来源及设备的磨损状态。通过理论分析、数值模拟及实验验证, 分析不同形态铁磁颗粒退磁场, 研究铁磁颗粒形态对电感式传感器的输出影响。建立理论模型描述不同形状颗粒的退磁因子、磁化场, 以及磁化的金属颗粒产生磁场从而导致线圈电感发生变化。基于模型计算并验证同体积下球形、不同轴长比的圆柱、椭球颗粒的磁场和电感输出, 分析结果显示颗粒越细长、退磁因子越小则越容易磁化, 因此细长颗粒引起传感器的电感变化更大, 另外圆柱形颗粒的电感变化大于旋转椭球型颗粒。     

液压油污染实验与在线监测模型

液压油污染物主要包括水和固体颗粒等。介绍了水污染液压油衰变模型(S-B模型)和固体颗粒污染液压油衰变模型(G-S)模型,以这两个模型为基础,建立了衰变液压油含水率在线监测模型和固体颗粒质量分数在线监测模型,并对其进行了实验验证。结果表明:两个模型能较好地实现衰变液压油含水率和铁粉质量分数的在线监测,有利于降低煤矿维修成本和保证液压系统正常运转。     

Micron Resolution Electromechanical Liquid Level Measurement System

Abstract

A new electromechanical liquid‐level measurement system, able to achieve measurements on micron sensitivity, is presented in this study. A simple stepping motor provides vertical movements to electrodes sensing the water level. A microcontroller installed on the system determines the number of steps executed by the motor when electrodes move between an upper reference plane and the level of the liquid to be measured below the reference plane. This number is transformed, by the micro‐controller, to the depth of the liquid level relative to the reference plane. The system is particularly useful for the detection of liquid level changes. The level sensor can be used, not only for precise water level measurements, but also for other non‐explosive and non‐flammable liquids and for conductive solid surfaces. Besides this, changes in water levels in natural lakes and in dam lakes, and fluctuations of the groundwater in wells can be sensitively detected by this sensor.