利用PDSC考察环境友好润滑油基础油氧化安定性的研究

结合环境友好润滑油产品的开发工作,用加压差热扫描示量法(PDSC)研究了菜籽油、双酯、多元醇酯等几种基础油的氧化稳定性,并与旋转氧弹的结果进行了比较;对菜籽油在不同温度下的氧化反应特性进行了考察,并采用阿仑尼乌斯公式计算了菜籽油氧化反应的活化能,初步研究了其氧化反应机制。试验结果表明,PDSC可用于评价基础油的氧化安定性,合成酯的氧化安定性明显优于菜籽油,且多元醇酯的氧化安定性最好。     

高压差热扫描分析技术在润滑油热氧化研究中的应用

对某型航空润滑油进行热氧化模拟试验 ,应用高压差热扫描分析仪 (PDSC)和GC评价润滑油中抗氧剂N-苯基 -α萘胺 (NPAN)的热氧化衰变程度。结果发现在该润滑油热氧化衰变过程中 ,1nCNPAN与PDSC的OIT (氧化诱导期 )具有极佳的线性相关性 ,表明PDSC是研究润滑油热氧化的理想手段     

PDSC法研究煤转化基础油的氧化安定性

用加压差示扫描量热法(PDSC)研究了煤转化的基础油(CTL)和Ⅲ类油以及Ⅳ类油(PAO)的氧化安定性,并考察了3种基础油对抗氧剂的感受性.结果表明CTL基础油的氧化安定性和Ⅲ类油接近,但是比Ⅳ类差.3种基础油对胺类抗氧剂(AO)的感受性相近,但Ⅳ类油的感受性最好.由煤转化而成的CTL基础油有可能成为Ⅲ类基础油的替代品.     

高压差热扫描分析技术在润滑油氧化研究中的应用

对某型航空润滑油进行热氧化模拟试验，应用高压差热扫描分析仪（PDSC）和GC评价润滑油中抗氧剂N－苯基－α萘胺（NPAN）的热氧化衰变程度。结果发现在该润滑油热氧化衰变过程中，lnCNPAN与PDSC的OIT（氧化诱导期）具有极佳的线性相关性，表胆PDSC是研究润滑油热氧化的理想手段。     

加氢异构基础油的氧化安定性研究

选用几种加氢异构化的基础油作为试验原料,采用核磁共振波谱法分析其烃类结构组成;利用加压差示扫描量热法(PDSC)研究基础油的异构化程度与氧化安定性的关系,考察异构化基础油对抗氧剂的感受性。结果表明,异构化程度高的基础油氧化安定性较好,对抗氧剂的感受性也较好。     

DOI:10.3969/j.issn.0254-0150.2012.08.023

选用几种加氢异构化的基础油作为试验原料,采用核磁共振波谱法分析其烃类结构组成;利用加压差示扫描量热法(PDSC)研究基础油的异构化程度与氧化安定性的关系,考察异构化基础油对抗氧剂的感受性.结果表明,异构化程度高的基础油氧化安定性较好,对抗氧剂的感受性也较好.     

不同加工工艺基础油结构特征对其性能的影响研究(Ⅱ)--芳烃结构等对其氧化安定性的影响

在采用液固色谱将基础油分离的基础上，利用四极杆质谱技术对加氢异构基础油、溶剂精制基础油的芳烃组成进行了详细的分析。在此基础上，将不同类型芳烃、硫氮模型化合物加入到两种基础油的饱和烃中，用DSC法考察了不同芳烃、硫氢模型化合物对基础油氧化性能的影响，将旋转氧弹法与DSC结合考察了添加剂对基础油氧化安定性的影响。     

一种不含硫磷氮硼酸酯的摩擦学性能研究

合成了一种不含硫磷氮的新型硼酸酯,在四球摩擦磨损试验机上研究了它们作为润滑油添加剂的摩擦学性能,用X-射线光电子能谱(XPS)分析了钢球磨损表面典型元素的化学状态,用加压差热扫描示量法(PDSC)评价了其在基础油中的抗氧化性能。实验结果表明,合成的硼酸酯具有良好的抗磨性能,是一类新型无硫磷氮环保型润滑油添加剂;在摩擦过程中,硼酸酯添加剂在钢球表面形成了一层含硼膜,这层膜具有良好的摩擦性性能;硼酸酯添加剂具有良好的氧化安定性,加入添加剂后基础油的起始氧化温度增加18.54℃。     

铜离子对直链烯烃基础油氧化安定性的影响

采用旋转氧弹法、热氧化法研究含Cu~+/Cu~(2+)的直链烯烃基础油的氧化安定性,考察反应温度、金属离子质量分数对氧化反应速度的影响。结果表明:80℃下Cu~+/Cu~(2+)的氧化作用大于120℃下;金属离子在诱导期促进氧化反应速率,其中Cu~+存在时的氧化反应速率大于Cu~(2+),但随着氧化的进行,金属离子抑制烯烃氧化反应速率。红外光谱分析结果表明,Cu~(2+)的存在促进了醛、酮及羧酸类化合物的生成,质量分数低于8×10~(-5)的Cu~+抑制了醛、酮及羧酸类化合物的生成。通过热力学计算解释了含Cu~+时直链烯烃氧化反应速率大的原因并证实了烯烃分子簇结构的存在。     

一种二烷基二硫代氨基甲酸酯抗氧抗磨多功能添加剂的合成及性能研究

以二丁基胺、二硫化碳、二氯甲烷为原料合成了亚甲基双丁基二硫代氨基甲酸酯,采用旋转氧弹法、高压差示扫描量热法、四球摩擦磨损试验法和成焦板等试验,考察了该添加剂在加氢润滑油基础油、合成基础油、CH-4柴油机油和工业齿轮油中的抗氧化性能和摩擦学性能.结果表明此添加剂具有良好的抗氧抗磨效果,和芳胺型抗氧剂具有良好的协同效应,能够降低高档油品中ZDDP的添加量,但铜片腐蚀性能比较差.     

Redesigning alkylated diphenylamine antioxidants for modern lubricants

This paper describes a new alkylation technology that is very effective at synthesizing structurally different alkylated diphenylamine chemistries relative to those currently available to lubricant formulators. Examples are provided showing how this technology can be used in a practical way to produce a variety of chemically modified nonylated diphenylamine types. One example is also provided illustrating the preparation of a higher molecular weight dodecylated diphenylamine. Engine oil performance data utilizing pressurized differential scanning calorimetry (PDSC), the thermo‐oxidation engine oil simulation test, and a bulk oil oxidation test demonstrate that subtle changes in alkylated diphenylamine chemical composition can result in significant oxidation and deposit control performance enhancements or losses. Examples of similar performance responses in industrial oils are demonstrated utilizing PDSC and the rotating pressure vessel oxidation test. These performance changes are directly related to specific structural changes in the modified products. Copyright © 2006 John Wiley & Sons, Ltd.     

Characterization of Model Perfluoropolyalkylethers by Miniaturized Thermal Oxidative Techniques–-Part II: Pressure Differential Scanning Calorimetry

Commercially available and model perfluoropolyalkylether (PFPAE) fluids were characterized by pressure differential scanning calorimetry (PDSC). Details of the PDSC method are described and the stabilities determined by PDSC are compared to those obtained from the constant temperature miniaturized oxidation corrosion test described in Part I of this paper (1). Chemical structure-thermal oxidative stability relationships of the fluids as derived from the PDSC method are discussed. The destabilizing effect of an -OCF2-group is confirmed and other more subtle effects are noted.     

Advanced lubricants for heat engines

An advanced liquid lubricant for heat engines has been developed and tested successfully in a prototype engine. The lubricant possesses superior oxidation stability and high temperature stability. With the advent of new engine designs, stability should be measured in terms of both the temperature and the time for which the lubricant is subjected to it. This lubricant is designed to provide friction and wear protection for three to five minutes at 425°C (800°F) at the ring zone and maintains stability at an oil sump temperature of 171°C. The lubricant has been evaluated by the Cummins Engine Company. Out of a field of several dozen lubricants, six lubricants were selected for a prototype 200 h endurance tests. The NIST lubricant was one of the two lubricants that successfully finished the endurance testing. This paper provides an overview of the key lubricant design considerations, including oxidation and thermal stability, volatility, and deposit control, the prototype engine test conditions and the results.     

Thermo‐oxidative stability of high‐temperature stability polyol ester jet engine oils — a comparison of test methods

Thermo‐oxidative stability in aerospace turbine oils is an important criterion. A new category (HTS) of turbine oil has been introduced, and the present work compares data on the oxidation stability of HTS oils obtained using the FTM 791, method 5308 test, at various temperatures, and PDSC experimental data, to standard class oils (STD). PDSC has become established in recent years as an effective means with which to establish the thermo‐oxidative stability of oils. The purpose of the present work was to find out whether PDSC could identify HTS oils correctly, and also to increase our understanding of some of the chemical processes behind the test results. Analogies in the degradation of the oligomer antioxidants have been confirmed by MALDITOF mass spectra.     

A comparative study of phenol‐type antioxidants in methyl oleate with quantum calculations and experiments

Chemical software (Gaussian 98w) was used to calculate the highest occupied molecular orbital (HOMO) energy level of three phenol‐type antioxidants to evaluate their oxidation resistance performance. The conclusion drawn from the quantum calculations was that the decreasing order of the oxidation resistance effectiveness was 4,4‐methylene‐di(2,6‐di‐t‐butyl‐phenol) (T511)>2,6‐di‐t‐butyl‐4‐methylphenol (BHT)>phenol. Pressure differential scanning calorimetry (PDSC) and the rotary bomb oxidation test were also used to assess the antioxidants in a methyl oleate base oil. According to the experimental results, the oxidation resistance capability of the three antioxidants decreased in the order BHT > T511 > phenol. The results indicated that the quantum calculation method could be used to screen antioxidants with regard to their oxidation resistance effectiveness.     

A Chemical Kinetics Model to Predict Diesel Engine Performance. Part II. Bench-Test Procedures

Bench tests have been used to screen lubricants and additives for industrial fluids in machinery applications for a long time. As the cost of engine testing increases dramatically, the need for simple laboratory bench tests increases. Bench tests simulate a particular aspect of the engine operation such as oxidation or wear, but the engine operation blends both mechanical, chemical, and combustion processes together and allows these parameters to interact freely. There are many bench tests providing a measure of oxidation stability under simulated conditions. For a given application, while the generic aspects of the lubricant degradation mechanism may be similar, environmental factors such as oxygen availability, the presence of specific metals (catalytic effects), and residence times of the oil at high-temperature regions may be specific to that application. Universal bench-test procedures that can predict oxidation stability therefore are not feasible. As described in part I of this paper, a computer simulation program has been developed combining a chemical kinetic model and a finite-difference program to simulate the engine operating conditions to predict lubricant performance in a diesel engine. This paper describes the bench-test procedures used to determine the kinetic constants used in the kinetic model to describe the lubricant degradation processes. The bench tests are specifically designed for the determination of kinetic constants in general for a particular reaction path but take into account the particular environmental factors intrinsic in the Caterpillar 1K engine dynamometer test.     

Development of engine crank-case oil formulations for oxidation stability using indigenously blended lubricant base-stocks

With changing engine design putting more emphasis on fuel economy, emissions control and low engine oil consumption, the quality levels of engine crank-case oils are changing fast. With this in view, experimental work has been carried out towards the development of engine crankcase-oil formulations meeting the required levels of oxidation stability. Three lubricant base-stocks meeting the physico-chemical characteristics of engine oils, prepared from lubricant streams obtained from different refined crude oils and one re-refined engine oil base-stock were used. The viscosity index of these base-stocks ranged from 84 to 98, and carbon residue from 0.06 to 2.2. The antioxidant used in the formulation was of ZDDP type, and the detergents were calcium and barium sulphonates. The base-stocks were evaluated using the IIP oxidation stability test, to determine their suitability in the formulation of engine crankcase oils. The base-stocks were then dosed with additives, and tested again by the IIP Oxidation Stability Bench Test, for their additive response. The final formulations were then tested on a CRC-L-38 standard engine test prescribed in Indian Standard 13656:1993 for IC Engine Crankcase Oils with respect to bearing corrosion and piston deposit tendencies. It was observed that higher VI lubricant base-stocks and the re-refined engine oil base-stock gave better test performance in both bench and standard engine tests.     

Mixture of safflower oil and synthetic ester as a base stock for biodegradable lubricants

Biodegradable industrial lubricant applications are gaining popularity with growing environmental concern and stringent government regulations. Plant oils are major base stocks for eco‐friendly green lubricants. However, because of their poor oxidation stability, their applications are restricted to limited usages. Improvements of these plant oils can be made either by addition of functional additives or by chemical/genetic modifications. This paper evaluates the synergistic approach of phenolic and aminic antioxidants in safflower oil. Further, to enhance the oxidation properties of the plant oil, we incorporated and studied synthetic esters (SEs) for thermo‐oxidative stability by using rotating pressure vessel oxidation test and differential scanning calorimeter. The combination of phenolic and aminic antioxidants at a 2 : 1 ratio exhibited the best synergistic effect, when incorporated into a combination of plant oil and SE. In addition to thermo‐oxidative properties, the tribological properties of neat base stocks were also studied. A substitute of mineral oil‐based lubricants can be formulated cost effectively by using an appropriate mixture of plant oil and SE. Copyright © 2013 John Wiley & Sons, Ltd.     

Studies of Rolling-Element Lubrication and Fatigue Life in a Reduced Pressure Environment

Fatigue tests were conducted in a modified five-ball fatigue tester on SAE 52100 steel ball specimens, at atmospheric pressure and at the approximate lubricant vapor pressure with two different lubrication methods, using a super-refined naphthenic mineral oil as the lubricant. Additional tests were conducted with AISI M-50 ball specimens with polyphenyl ether lubricants. Differences in fatigue life, deformation and wear with the mineral oil lubricant were insignificant regardless of the ambient pressure environment or lubrication method employed. Polyphenyl ether lubricants exhibited large amounts of wear both at atmospheric and reduced pressures, indicating a lack of an elastohydrodynamic film with this lubricant under the stresses and sliding velocities present in the five-ball fatigue tester.