不同氧化条件下柴油机油的氧化降解研究

为探讨氧化温度、时间以及金属催化氧化等因素对柴油机油性能的影响,采用高温烘箱以及氧化测试仪模拟不用的氧化条件,研究柴油机油氧化前后部分理化性能、摩擦学性能的变化,分析不同氧化条件对柴油机油的氧化过程及性能的影响规律.结果表明:高温烘箱试验后发动机油的理化性能、抗氧化性能以及摩擦学性能会有一定程度的劣化,但变化幅度不大,...     

基于综合劣化值的钻井服役柴油机油健康状态评估方法

针对GB/T 7607—2010标准对于钻井服役柴油机油健康状态评估可参考性不强的问题，参照PHM理论中健康状态评估技术建立服役柴油机油健康状态评估的综合劣化值模型；根据对监测数据的统计和实验室经验对综合劣化值与服役柴油机油健康状态对应关系进行分级，按照指标的单调性、相关性、预测性这三项原则选取服役柴油机油健康状态评估指标，给出各类指标数值归一化的方法；基于熵权法确定各项指标的权重，建立服役柴油机油综合劣化值计算公式，计算各样品数据的综合劣化值。通过不同综合劣化值样品的红外图谱中抗氧剂特征峰的比较，验证了方法的可靠性。     

发动机油的碱值保持能力与抗氧化性能关系

为探讨发动机油的碱值保持与抗氧化性能的关系,通过模拟试验和行车试验考察使用过程中发动机油的酸值、碱值的变化,分析发动机油抗氧化性能与碱值保持的关系,并从碱值分析技术缺陷入手初步探讨如何看待和分析发动机油碱值的变化。结果表明:油品氧化过程中碱值降低与酸值增加量之间无明确的对应关系,单纯使用碱值进行发动机油的性能监测和判断油品的抗氧化性能好坏并不科学;由于影响发动机油性能的因素较多,用行车试验来研究碱值的变化与抗氧化性能关系,很难得出理想的结果。     

油酸甲酯对柴油机油热氧化性能影响研究

为研究生物柴油对柴油机油的影响,在柴油机油中分别加入质量分数10%和20%油酸甲酯,研究氧化前后油酸甲酯对柴油机油黏度、酸值和正戊烷不溶物含量的影响,量化了不同油酸甲酯含量对柴油机油各理化性能的影响百分比,从而得到不同油酸甲酯含量对柴油机油热氧化性能影响的总体百分比。结果表明:油酸甲酯的加入加快了柴油机油样品中高分子聚合物、酸性物质和正戊烷不溶物的生成,导致黏度和酸值增加;油酸甲酯对柴油机油酸值的影响最大,对黏度的影响其次,对不溶物含量的影响最小,说明加入油酸甲酯后,易较快地生成酸性物质是其诱导柴油机油氧化变质的主要原因;加入油酸甲酯越多,油酸甲酯对柴油机油热氧化性能的影响越大,这是因为随着油酸甲酯的逐渐加入,它的稀释作用会使柴油机油的性能衰减加剧。     

煤矿用螺杆空气压缩机油劣化试验研究

通过对煤矿用螺杆空气压缩机油每隔一段运行时间的粘度、酸值、机械杂质、闪点、残炭等指标检测,研究了螺杆空气压缩机油劣化规律。结果表明:随着运行时间的增加,粘度、酸值、机械杂质、残炭值逐渐增大,3021h内增长速度较缓,3021h后增长速度明显加快;闪点变化不明显。此外,结合试验数据分析了上述指标变化的原因,指出了煤矿用螺杆空气压缩机油劣化防范措施。     

实际工况下红外光谱法测润滑油总酸值的研究

针对实际工况下采集的在用润滑油,依据ASTM标准试验方法与条件,采用傅里叶红外光谱法与自动电位滴定法分别测得氧化度与总酸值,并研究得到二者之间的相关关系模型。结果表明:从整体上看氧化度与总酸值高度相关,说明用红外光谱测定的氧化度代替电位滴定法测定的总酸值是可行的。但不同类型的油品总酸值与红外氧化度之间的关系存在较大差异,以氧化度理论计算总酸值需要有足够多的样品实测数据基础。     

基于介电常数法的油液监测

提出了基于介电常数法的油液监测方法,分析了介电常数法油液监测的原理,通过试验研究了润滑油的主要理化指标与其介电常数之间的变化规律.结果表明,影响润滑油介电常数的主要理化指标是水分、酸值和金属磨粒;介电常数作为润滑油的劣化评价指标是可行的.     

汽车发动机润滑油劣化规律的试验研究

应用理化性能指标快速检测法和铁谱分析法，对在用车润滑油每隔一定里程抽取油样，检测了其含水量、酸值、闪点、燃点以及铁屑浓度等指标，研究了在用车润滑油的劣化规律。结果表明，随着行车里程的增加，在用发动机油的含水量和酸值增高，闪点和燃点降低，铁屑浓度缓慢增加；应用润滑油理化性能指标快速检测法，能够定量地评价发动机润滑油品质的变化程度，实现按质换油，应用铁谱分析法对发动机的状态进行监测，能够定量地评价发动机机件的磨损程度，实现发动机视情维修。     

基于红外光谱的在用润滑油衰变信息的快速确定和关联性分析

分析了某合成的在用航空润滑油的组成和需检测的指标项目,研究了润滑油红外光谱信息与检测项目之间的关系。采用偏最小二乘法、人工神经网络法等建立红外光谱和运动粘度、闪点、酸值和水分等理化指标的多元校正分析模型。根据朗伯-比尔定律,建立红外光谱峰面积或峰高与被测组分的工作曲线,实现了燃油、抗氧剂、抗磨剂的定量分析。针对基础油酯基降解程度无法定量检测的特点,将酯基降解与酸值、粘度值进行关联性研究,酸值与酯基降解红外谱峰相关性很好,可通过酸值变化确定酯基降解程度。     

紫外光谱作为车用润滑油失效判断的研究

提出基于紫外光谱法的油液监测方法,通过试验研究润滑油的主要理化指标酸值与其紫外吸光度之间的变化规律,建立紫外吸光度的威布尔模型。结果表明,紫外光谱法作为润滑油的劣化评价指标是可行的,并给出了不同可靠度下的紫外吸光度变化量作为指标的油液失效阈值。     

基于红外光谱技术的两用燃料发动机油抗劣化性研究

应用红外光谱技术,根据润滑油组分中各官能团的红外光谱吸收峰的出现和变化,研究了开发的CNG/汽油两用燃料发动机润滑油与参比油在运行期间,润滑油的氧化值、硝化值、硫化值的变化程度,发现CNG/汽油两用燃料发动机润滑油运行18 000 km后,其氧化值变化范围为2.45(ABS/0.1 mm)、硝化值变化范围为2.03(ABS/0.1 mm)、硫化值变化范围为3.85(ABS/0.1 mm)。结果表明CNG/汽油两用燃料发动机润滑油有着良好的抗劣化性能,红外光谱技术是研究润滑油抗劣化性的有效方法之一。     

甲醇汽油对汽油机油氧化和硝化的影响

应用红外光谱技术,根据不同物质在红外光谱仪中的吸光度不同,研究了在汽油机油中加入不同配比和含量的甲醇、甲醛和甲酸对汽油机油的抗氧化性和抗硝化性的影响。结果表明,加入甲醇、甲醛和甲酸后的油样和汽油机油相比,氧化和硝化程度都增大了;加入甲醇汽油的油样和加入甲酸或甲醛的油样相比,硝化值和氧化值都比较大,表明甲醇汽油对汽油机油的抗氧化性和抗硝化性的影响最大,甲醛和甲酸的影响较小。     

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.     

Comparison of engine oil degradation observed in laboratory alteration and in the engine by chemometric data evaluation

The influence of ethanol in gasoline and its partial combustion products on the engine oil performance was investigated by joint use of IR spectroscopic data and chemometrics. Oil samples obtained from artificial alteration in the laboratory and engine alteration in a chassis dynamometer were compared. Quantification of residual amounts of antioxidant and antiwear additive (ZDDP) in the oil samples by FTIR spectroscopy showed depletion of phenolic antioxidant during engine alteration but ZDDP degradation during artificial alteration. Different chemometrical models using principal component analysis (PCA) elucidated similarities and differences between both alteration types, proving the findings of FTIR spectroscopy. Additionally, laboratory-based artificial alteration was mainly driven by oxidative processes whereas engine alteration showed higher amounts of both oxidation and nitration products.     

Polyfunctional PIB succinimide type engine oil additives

The physical and chemical properties of polyisobutylene (PIB) succinimide and polyisobutylene polysuccinimide type dispers‐ants for engine oil have been studied. Differences in the enhancement or diminution of detergent‐dispersant, viscosity‐index‐improving, and antiwear effects were observed for different combinations of various functional additives and succinimide dispersants, depending on their chemical structure. Owing to the higher concentration of performance packages presently required for engine oils, the detrimental interactions of additives might increase, resulting in a reduction of the detergent‐dispersant, viscosity‐index‐improving, and antiwear efficiency, as well as unfavourable gelation processes. Fourier‐transform infrared spectrometry, gel permeation chromatography, and bench tests for screening engine oil additives were used to determined relationships between the properties of lubricating oils and the composition of additives. The advantages of well balanced and selected succinimide combinations in a performance package with high detergent‐dispersant efficiency were demonstrated.     

Oxidation stability of gasoline engine lubricants: Effect of base-oil chemistry in laboratory and engine tests

This paper presents a laboratory test called the Iron Catalysed Oxidation Test (ICOT), where air is bubbled through an oil sample at 165 °C. This test, shorter than the CEC L-48 test, provides an easy method of gasoline engine lubricant screening. A basic study has shown that this kind of test is suitable for the discrimination of base-oil properties and that the oil viscosity increase at the end of the test is highly indicative of the oxidation processes at work. In this study, the base-oil assessment is carried out with an API SG SAE 15W-40 oil, and the results depend directly on the aromaticity of the base oil. Several engine test sequences, including CEC L-55-T-95: TU3M HT, were also applied to these formulations, which differ only in their base oils. The results of those sequences where oil consumption was low roughly correlated with the laboratory test results. However, when there was a high loss of volatile matter in the engine tests, the oil viscosity increase was greatly modified, and this parameter can override the effect of oxidation.     

Studies on the effects of temperature on the chemical characteristics of automotive crankcase oils and their base oils

The effects of varying temperature regimes on the chemical characteristics of commercial mineral-based automotive crankcase oils and their base oils have been studied experimentally. This was achieved by simulating the hot-spot temperatures of parts of the engine surfaces, in an oxidizing atmosphere, using a modified version of the turbine oil oxidation test apparatus developed in our laboratory. The changes in the chemical characteristics of the engine oils and their base oils were studied with infrared spectroscopy, and tests of the oil-soluble acids, the acidity of the volatiles, the carbonyl peak index and the deposit formation.All the oils studied were found to possess high sensitivity to changes in temperatures. The types and nature of the hydrocarbons found in the base oils determined the nature of the volatiles and deposits formed. It has also been found that at temperature above 260°C, polymerization reactions in the fully formulated engine oils were greatly accelerated. In contrast, the base oils showed increases in carbonyl peak index but yielded low deposits. Thus suggested that under these conditions, the products of additive breakdown, may be catalysing the polymerization reactions.     

红外波谱技术在轴承润滑脂分析上的应用

探讨了红外波谱分析技术在轴承润滑脂分析及鉴别中的应用。除了分析脂中各类基础油、添加剂及稠化剂的特征波谱外，还讨论了利用波谱技术的结果来表征轴承润滑脂化学劣变参数，研究不同环境、试验条件及各类污染物对脂润滑机械部件失效的影响。波谱分析技术是一种快速、可靠和极为有效地分析手段，可应用于各类脂润滑的磨损监测及轴承的失效分析。