A Surface Effect Associated with the Use of Oils Containing Zinc Dialkyl Dithiophosphate

It is shown that the operation of engines on crankcase oils containing appreciable amounts of zinc dialkyl dithiophosphate can increase the small-scale roughness of the lifter-foot surfaces. In addition, the small-scale roughness can be reduced by subsequent operation of the same engine parts on oils containing no zinc dialkyl dithiophosphate. This change in roughness coincides with a change in reflectivity that can be detected visually.

A similar effect of the additive has been demonstrated in a bench test machine. The increase in roughness which accompanies the operation on the additive-treated oil occurs rapidly and is maintained to high contact loads although some smoothing may occur at high loads.

The evidence suggests that the change in roughness results from a reaction of additive decomposition products with the metal surface. The mechanism responsible, however, is not completely understood.     

The Influence of Copper-Containing Additives on Oil Oxidation and Corrosion

The effects of transition metals in either catalyzing or inhibiting oil oxidation in the liquid phase have been extensively reported in the literature. However, little attention has been paid to the surface films formed as by-products of these reactions. In this paper, the authors investigated surface films for the important case of copper-containing additives influencing the oxidation of oil that contacts a steel surface. Copper naphthenate in solution was found to inhibit oil oxidation and to form copper-containing precipitates and deposits on the steel surface. The surface films formed were characterized by X-ray photoelectron spectroscopy, Auger spectroscopy and scanning electron microscopy. The precipitates showed a unique morphology of spherical particles several microns in diameter. A high level of copper naphthenate was found to prevent corrosion of the steel surface.     

Study on Sludge Formation during the Oxidation Process of Turbine Oils

Against the backdrop of increased needs for longer operating life of turbine oils, there is a tendency to use amine-type antioxidants for steam turbine oils as well as gas turbine oils. Amine-type antioxidants are known to form sludge during the oxidation process, and the sludge formation from turbine oils involves the high risk for a power plant of bearing temperature rise caused by sludge deposition onto the bearing surface. But currently, there is no global specification to evaluate the sludge formation from turbine oils that have high rotating bomb oxidation test (RBOT) life. In this study, we examined 18 kinds of commercially produced turbine oils and two kinds of originally prepared oils with amine additives on sludge formation under 120°C dry turbine oil oxidation stability test (TOST) accelerated degradation test. Consequently, we found a criterion to check the quality of sludge resistance of turbine oils based on the relationship between the RBOT residual ratio and weight of filter residues(1μ m pore filter).     

Oxidation Stability and Tribological Behavior of Vegetable Oil Hydraulic Fluids

The new generation of vegetable oil hydraulic fluids has a price advantage and provides field longevity comparable to synthetic esters at moderate temperature.

This article investigates the oxidation stability and tribological behavior of fully formulated vegetable oil hydraulic fluids. Differences in origin (canola, soybean, and sunflower oil) and the degree of unsaturation are studied. Modified ASTM D943 (Dry TOST) was found reliable to evaluate the impact on oxidative stability of various additive packages in vegetable oils. Tribological testing utilized laboratory hydraulic pumps such as the Vickers V 104C, Vickers 20VQ, and Vickers PFB-5 under a variety of temperatures, pressures, pump outputs, and speeds. The conditions of aging fluids were monitored by evaluation of TAN, viscosity, wear rate, and depletion of antioxidants. Voltammetric technique was applied to determine the concentration of antioxidant in systems. Based on analysis of antioxidant consumption, the main degenerative process in vegetable oils under demanding pump operations is similar to pyrolytic degradation, rather than oxidation.

By selecting the appropriate synergistic additive packages, a remarkable pump longevity can be obtained for each vegetable base stock studied.     

Protic Ionic Liquids with Ammonium Salts as Lubricants for Magnetic Thin Film Media

The newly synthesized perfluoropolyether (PFPE) whose terminal group is an ammonium salt with a carboxylic acid has better frictional and anti-corrosion properties when compared to the conventional PFPEs. The friction is almost independent of the PFPE structure, but depends on the amine structures. This modified PFPE uniformly covers the magnetic surfaces; this is why it not only reduces the friction, but also has an effect on the corrosion resistance.     

航发叶片有限元建模与罩量优化设计系统开发

以ANSYS为计算分析平台,开发了叶片有限元建模与罩量优化设计系统。该系统将叶片的罩量设计理论、有限元数值计算方法以及现代优化设计技术结合起来,形成了叶片有限元建模与罩量优化设计平台,为叶片的快速有限元建模和罩量优化设计提供了一个强有力的高效设计工具。     

Investigation of nonlinear numerical mathematical model of a multiple shaft gas turbine unit

The development of numerical mathematical model to calculate both the static and dynamic characteristics of a multi-shaft gas turbine consisting of a single combustion chamber, including advanced cycle components such as intercooler and regenerator is presented in this paper. The numerical mathematical model is based on the simplified assumptions that quasi-static characteristic of turbo-machine and injector is used, total pressure loss and heat transfer relation for static calculation neglecting fuel transport time delay can be employed. The supercharger power has a cubical relation to its rotating velocity. The accuracy of each calculation is confirmed by monitoring mass and energy balances with comparative calculations for different time steps of integration. The features of the studied gas turbine scheme are the starting device with compressed air volumes and injector’s supercharging the air directly ahead of the combustion chamber.     

A high accuracy dilution system for generating low concentration reference standards of reactive gases

We have developed a unique dynamic dilution system for generating high accuracy reference standards of reactive gases at concentrations which are unstable in high pressure cylinders. It uses state of the art ‘Molbloc’ flow elements and is capable of generating adjustable reference standards with an estimated relative expanded uncertainty lower than 1%. This is a significant development, improving the accuracy of primary reference gas mixtures used to provide and disseminate traceability for measurements of many key gaseous air pollutants.     

复杂机电产品动态可靠性建模理论与方法研究

分析传统可靠性建模方法在描述时间及系统动态过程等方面存在的缺陷,研究了影响系统动态可靠性的各种因素,给出动态可靠性的定义及理论体系。在评述已有动态可靠性建模方法的特点及其应用的基础上,提出复杂系统动态可靠性建模的发展方向。     

A Simulation Scheme with Coupled Dynamic Models for the Slider and the Suspension Lift-Tab during the Unloading Process of a Hard Disk Drive

A numerical scheme was developed to simulate the interaction between the suspension lift-tab and the ramp of a load/unload-type hard disk drive with consideration of the contact and separation states. The suspension stiffnesses and effective masses were determined based on experiments and finite element analysis. The slider motion was simulated with a degenerated two-degree-of-freedom model, and the results were used as input to a single-degree-of-freedom model for the lift-tab motion. The ramp profile was converted, based on the lateral velocity of the suspension, to a vertical displacement versus time. Computational efficiency was achieved by using a head–disk constraint, instead of a full air-bearing solution, based on dual-scale considerations. The simulation results show that the maximum indentation depth at the tab–ramp engagement increases with an increase in the effective masses, lateral velocity, or ramp angle or with a decrease in the contact stiffness. The bouncing height and bouncing distance of the lift-tab increase with an increase in the contact stiffness, effective masses, lateral velocity, or with a decrease in the suspension stiffnesses. The air-bearing separation time decreases as the suspension stiffnesses, lateral velocity, or ramp angle increases. The coefficient of friction of the tab–ramp interface was found to have a slight influence on the lift-tab behavior on the inclined portion of the ramp.