润滑油含磷添加剂结构表征和齿轮机试验中热稳定性研究

利用气质联用、质谱和核磁验证润滑油添加剂T306（磷酸三甲酚酯）和T310A（硫代磷酸酯胺盐）的组成和结构,并采用核磁共振磷谱(31P-NMR)检测齿轮机试验前后润滑油中磷系添加剂结构的变化。研究表明,T306具有优异的热稳定性和抗磨性,适用于高温的工况; T310A具有较好的氧化安定性、抗摩擦能力和磷保持能力,适用于温度高、周期长的苛刻工况。不同的含磷添加剂热力学稳定性不同,所适合的工况也存在差异。利用核磁共振磷谱可以判断不同含磷添加剂所适用的工况以及在该工况条件下添加剂的结构变化情况,从而可通过对含磷添加剂的监测来判断油品的质量。     

Pitting load capacity test on the FZG gear test rig with load-spectra and one-stage investigations

Lubricants in their combination of base oil and additive influence the pitting and micropitting load-carrying capacity of cylindrical gears. The aim of the FVA ‘Pitting test’ research project was to develop and establish a test method on the standard FZG gear test rig with a centre distance a = 91.5 mm. Two different test procedures were proposed, one using a load spectrum and the other a constant load. These tests can be used to determine the relative pitting load capacities of reference and candidate oils. From these results the pitting load-carrying capacity can be calculated.     

Assessing the energy efficiency of gear oils via the FZG test machine

Energy efficient lubricants are becoming increasingly popular. This is due to a global increase in environmental awareness combined with the potential of reducing operating costs. A new test method of evaluating the energy efficiency of gear oils has been described in this report. The method involves measuring the power required by an FZG test rig to run while using a particular test lubricant. For each oil that was being evaluated, the rig was run for 10 minutes at a load stage of 10. Six extreme pressure (EP) industrial gear oils of mineral base were tested. The difference in power requirements between the best and the worst performing oils was 2.77 and 3.24 kW, respectively. This equates to a 14.6% reduction in power, a significant amount if considered in relation to a high powered industrial machine. The oils of superior performance were noticed to run at reduced temperatures. They were also more expensive than the other products of lesser performance.     

Organophosphorus chemistry structure and performance relationships in FZG gear tests

A model investigation was conducted involving several different molecular weight phosphorus compounds prepared in base stocks of various polarities. The study involves two different parts. In one part, the same phosphorus compound was blended into several base stocks of differing polarities and was observed to give differing FZG gear test results. In part two, several different phosphorus compounds of various molecular weights were blended into the same base fluid and were observed to give differing FZG gear test results. Solution properties were studied by dielectric thermal analysis and afforded data as to mobility and surface reactivity. X-ray photoelectron spectroscopy was performed on sectioned gear teeth and provided elemental composition as well as thickness of the reacted surface layer. This data was correlated with the recorded FZG gear test results. A surface interaction mechanism is proposed that accounts for the relative phosphorus content and thickness of the wear protection films. The mechanism is based on correlating the additive molecular weight and base stock polarity as it relates to the FZG gear stage test pass result.     

Evaluation of surface fatigue performance of gear oils

The effect of additive chemistry on the surface fatigue of gears was investigated using an FZG gear tester and fluids based on an API GL-5 grade gear oil. Surface fatigue lives were determined as a function of load and additive chemistry. At 1.52 GPa, the removal of the primary extreme pressure (EP) additive from the fully formulated gear oil decreased the fatigue life of gears slightly (4%). However, the removal of the primary antiwear (AW) additive decreased the fatigue life of gears significantly (83%). At 1.86 GPa, the removal of the EP additive from the fully formulated gear oil decreased the gear fatigue life by 27%. However, the removal of the primary AW additive decreased the fatigue life of gears significantly (75%). Micro-pitting was the dominant surface morphology in the dedendum of the gears tested with two oils at load stage eleven: one using the complete additive package, and a second where the EP additive had been removed. However, spalling was the primary failure mode of gears tested without an AW additive, independent of whether an EP agent was present. Surface analysis of the pinion gears showed the formation of a mixed phosphate/phosphite—oxide layer on the surface of gears tested with fluids containing an AW additive. Formation of this layer seems to be the key to a long fatigue life.     

A scuffing load capacity test with the FZG gear test rig for gear lubricants with high EP performance

Methods for the evaluation of the scuffing load capacity of EP lubricants of API GL-4 and GL-5 performance levels have been developed for the standard FZG gear test rig, which has a centre distance of a = 91.5 mm. Procedure A10/16.6R/90 is capable of discriminating between industrial gear oils and automotive gear oils up to GL-4 performance level while procedure S-A10/16.6R/90 can be applied to GL-4 and GL-5 lubricants. The test methods were verified with reference oils and commercial gear lubricants. The results of the tests can be used to give a relative ranking of reference and candidate lubricants. They can also be used as limiting values in the scuffing load capacity rating method according to DIN 3990 (ISO DIS 6336).     

Influence of Rolling Element Bearing Modeling on the Predicted Thermal Behavior of the FZG Test Rig

A thermomechanical model of the FZG test rig is presented. The numerical model is based on the thermal network method and takes into account power losses due to tooth friction, rolling element bearings (REBs), oil churning, and shaft seals. Some measurements underline that REB rings run at different temperatures. To investigate this difference, several REB models are proposed and compared to measurements. Their influence on the global thermal behavior of the gear unit is discussed and analyzed.     

基于FZG齿轮试验机的润滑油抗点蚀性能评价

在机械传动接触中，点蚀是一种常见的疲劳失效形式。润滑油基础油和添加剂的性能决定着齿轮出现点蚀的时间，以及点蚀的大小和数量。点蚀试验在FZG试验机上进行，选用标准C型齿轮，观测齿面点蚀的面积和时间，计算点蚀寿命，对该油品的抗点蚀能力进行评价。文章介绍了导致出现点蚀的主要原理和油品抗点蚀性能的评价方法。     

Laboratory shearing tests for viscosity index improvers

The relative resistance of VI improvers to breakdown depends on internal structural parameters (chemical type, ratio of monomers, degree of branching) as well as on external factors (test type, duration, severity). Of the many bench tests available to screen shear stability, the 30 cycle CEC injector test is most commonly used for engine oils. Test duration, however, can significantly change the relative ranking of VI improver shear stability. While some polymers stabilise quickly, others continue to degrade when test duration is extended. Some polymers are also more susceptible to the severity of the shearing conditions encountered, e.g. in the FZG and the Tapered Bearing tests. It is therefore important to determine which test, and which set of conditions, will rank shear stability of different VI improver types in the same order as does the field.     

Wear investigation of spur gear teeth

An FZG back‐to‐back gear test machine has been used to investigate the initial wear of spur gears. By making plastic replicas of the tooth surfaces, and measurements of the same using a 3D stylus instrument, the wear pattern has been analysed. The wear tests were run on the machine according to a predefined schedule. During planned stops, negative surface replicas were made. The replicas were measured, and the amount and distribution of wear analysed. SEM pictures were also taken of the tooth surfaces, and several different types of damage were identified. The results were compared with simulated results using identical loading and geometry. It was found that the wear was quite severe at the root of the wheels and also significant at the tip. The wear was also found to form an overloaded wave pattern on the original involute form of the tooth.