酯类航空润滑油热氧化安定性研究现状

随着航空发动机工作环境温度的不断提高,对润滑油热氧化安定性的要求也越来越严格。介绍了酯类航空润滑油抗氧剂分类及抗氧化机理;综述了氧化试管法、旋转氧弹法和扫描量热法等润滑油热氧化性评定方法,以及航空润滑油热氧化安定性研究现状。最后指出酯类航空润滑油热氧化安定性在发动机补油、换油和故障预测方法都具有现实意义。     

航空润滑油性能衰变影响因素的研究进展

本文结合国内外相关研究现状,根据航空涡轮发动机润滑油的实际工作特点,主要对温度等外界因素对润滑油热氧化安定性等关键性使用指标的影响进行了综述。     

润滑油热氧化安定性试验方法标准比较分析

概述了物质组成、温度、金属和氧气等因素对润滑油高温氧化安定性的影响,将国内润滑油热氧化安定性试验方法标准分为旋转氧弹法、氧化管法、设备模拟法和仪器分析法,并进行分类介绍。     

金属磨粒对航空发动机润滑油氧化安定性的影响探究

从航空润滑油氧化安定性的定义、影响因素、危害等方面入手,对金属磨粒在航空润滑油氧化安定性方面的研究进行了综述,最后对航空润滑油氧化机理和金属作用机理进行了深入探讨。     

PDSC法分析聚α-烯烃航空润滑油基础油的氧化安定性研究

利用高压差示扫描量热法(PDSC),通过测定国产和进口聚烯烃航空润滑油基础油的起始氧化温度,比较两种基础油的氧化安定性,同时考察了两种基础油对三种不同类型的抗氧剂的感受性,确定了抗氧剂最佳配比。从实验结果来看,国产PAO航空润滑油的氧化安定性略低于进口PAO航空润滑油,但二者的氧化安定性相差不大,而对于PAO航空润滑油来说,胺型抗氧剂的抗氧化性能优于酚型抗氧剂。     

航空润滑油使用性能浅析

航空润滑油应具有良好的综合性能,文章对航空润滑油的润滑性、抗腐蚀性、氧化安定性等性能进行介绍,为更好地研究和使用航空润滑油提供帮助。     

航空润滑油关键性使用指标分析

航空发动机润滑油的润滑性、氧化安定性、低温流动性和腐蚀性四个关键性使用指标在评价航空润滑油质量和性能过程中尤为重要,本文从定义、危害、评价因素、常用试验方法和标准等方面进行了分析,为飞机用油安全和航空润滑油性能及质量评价提供保障。     

植物油基润滑油应用研究现状

植物油具有生物可降解性、低挥发性、优良的润滑性和良好的黏温性,但植物油存在热氧化安定性差、低温性能差等缺陷,不能直接作润滑油和润滑添加剂应用,需要对其进行改性。常用化学改性方法有选择性氢化、酯交换和环氧化等,其中环氧化-开环反应引入活性基团和双键上的自由基加成反应是合成植物基润滑油添加剂的两种有效的改性方法。最后,就改性植物油用作可降解润滑油基础油和添加剂提出了研究方向并做了展望。     

酯类润滑油热氧化颜色变化研究

颜色变化是润滑油热氧化安定性最直接的外观表现之一。实验分析了不同温度(120、150、180、210和240 oC)下,癸二酸二异辛酯(DOS)和己二酸二异辛酯(DOA)两种润滑油基础油在无氮气保护、1.5×10~5Pa氧气及1.5×10~5 Pa氧气同时添加0.5%的抗氧剂N-苯基-α-萘胺(NPNA)的颜色变化规律,结果表明NPNA是导致润滑油颜色变黑的主要原因。     

酯类合成航空润滑基础油特性分析

分析了酯类合成航空润滑基础油的结构与性能,重点研究了双酯和多元醇酯的分子结构差异,双酯分子中醇端β碳原子上含有活泼氢原子,而多元醇酯β碳原子位置完全被烷烃羟基取代,因此多元醇酯的化学稳定性得到强化,比双酯具有更高的分解温度、更好的热氧化安定性。     

Deposit formation in liquid fuels. 1. Effect of coal-derived Lewis bases on storage stability of Jet A turbine fuel

The development of reasonably precise techniques for the measurement of storage stability of jet aviation fuel is described. Lewis bases, extracted by ligand-exchange from a coal-derived liquid, are shown to adversely affect storage stability (as determined by an accelerated storage test) when added to Jet A turbine fuel. JFTOT results suggesting slight decreases in thermal stability of fuel ‘spiked’ (i.e. contaminated with a measured quantity of reagent) with extract are reported. Addition to Jet A turbine fuel of individual heterocyclic nitrogen compounds is shown to produce comparable decreases in storage stability.     

油酸甲酯与ZDDP交互作用对柴油机油抗氧抗磨性能的影响

为更好的研究脂肪酸甲酯与柴油机油添加剂之间的交互作用,迚一步揭示生物柴油对柴油机油性能的影响。采用旋转氧弹法、热重法等手段研究了油酸甲酯与ZDDP的交互作用对柴油机油氧化安定性和热稳定性的影响,通过红外光谱分析了氧化前后柴油机油结构组成的变化,利用抗磨性试验考察并探讨了氧化前后油酸甲酯与ZDDP的交互作用对柴油机油抗磨性能的影响规律。结果表明:油酸甲酯显著劣化柴油机油的氧化安定性;油酸甲酯与ZDDP交互作用降低柴油机油的热稳定性;在给定试验条件下,油酸甲酯一定程度上改善了基础油的抗磨减摩性能,油酸甲酯与ZDDP交互作用会降低柴油机油的抗磨性能。     

Soot formation in gas turbines using heavy fuels. 1

The aim of this study was to determine the impact of the broadening of fuel specifications on the performance of a gas turbine combustor, particularly on soot formation and oxidation, and flame tube durability. Tests were conducted with a fully-developed combustor system, the main measurements comprising total radiation, exhaust smoke and temperatures at different locations. Five fuels were used: kerosine, as aviation fuel; gas oil, as the current industrial gas turbine fuel and possible future aviation fuel; R25 (where 25 is the volume percentage of residual fuel oil in the blend with gas oil), as equivalent to crude oil now in use in many utility gas turbines; and also R50 and R70 to represent future heavier fuels. Combustor pressures were 0.3, 0.7 and 1.0 MPa. Inlet air temperatures were 313, 390 and 460 K. Primary zone air/fuel mass ratios were 12, 15 and 25. Total air/fuel ratios were 60 and 120. Attempts were made to develop a mathematical model of the soot formation-oxidation processes that occur in the system, and to include in the model some parameters to represent the change in fuel properties. In this paper, comparison of the soot formation predictions of the model with the experimental data is seen to be favourable, particularly at full power conditions.     

聚α-烯烃润滑基础油热氧化安定性试验研究

文章利用薄层油膜氧化试验与红外光谱分析联用技术模拟试验研究了聚α-烯烃润滑基础油的热氧化安定性能,通过试验研究,得到了油样氧化后沉积物含量、油样质量损失和红外面积比CSI随氧化时间变化的关系,对了解润滑油的氧化稳定性和氧化降解机理具有十分重要的意义。     

聚α-烯烃航空润滑基础油高温裂解衰变研究

随着飞机发动机工作温度的不断提高,在用航空润滑油品质衰变问题越发严重,特别是聚α-烯烃航空润滑基础油在高温作用下会发生严重的裂解衰变,由此引发聚α-烯烃航空润滑油性能改变,难以满足现代飞机发动机使用的要求。从聚α-烯烃的本体结构特点出发,分析了聚α-烯烃润滑基础油在高温作用下热裂解的衰变过程,比较了聚α-烯烃润滑基础油高温裂解前后理化性能的变化,并且论述了聚α-烯烃航空润滑基础油高温热裂解衰变程度评定方法。     

提高润滑油基础油氧化安定性的方法

南阳石蜡精细化工厂由于在南阳稀油中掺炼南阳稠油,使润滑油基础油氧化安定性变差。本文介绍了南阳混合原油润滑油基础油性质及氧化安定性与油品组成的关系。通过对提高糠醛溶剂精制深度、对精制溶剂的改性、糠醛溶剂加入抗氧剂、WSQ—2脱氮剂液相脱氮工艺等方法的比较,探讨了如何利用现有装置改善基础油氧化安定性的途径。     

Soybean oil induced efficient thermal–oxidative degradation of covalently crosslinked styrene butadiene rubber

It has been a technical challenge of recycling tire rubbers due to the covalently crosslinked polymer network structure. Unlike conventional recombination of crosslinked SBR under thermal oxidation, SBR vulcanizate was efficiently degraded by thermal oxidation at 150 °C in presence of soybean oil, resulting in 47.3% sol fraction by weight. The structural evolution of SBR vulcanizates during thermal oxidation was characterized by sol–gel ratio, chemical structure, molecular weight, and oxidative erosion on the rubber surface. It was found that the continuous oxidation process facilitated main chain scission of SBR vulcanizates, resulting in a decrease of molecular weight of the sol fraction. The concentration of carbonyl groups, sol fraction, and surface erosion continually increased with reaction time. The large amounts of soybean oil significantly affect the thermal stability of SBR vulcanizates. Moreover, soybean oil is more efficient in decomposition of the SBR vulcanizates and results in more homogeneous and efficient oxidation reactions than paraffin oil. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48935.     

Flammability hazards of typical fuels used in wind turbine nacelle

This study aims to develop a complete methodology for assessing flammability hazards of typical fuels (ie, transformer oil, hydraulic oil, gear oil, and lubricating grease) used in a wind turbine nacelle by combining different experimental techniques such as thermogravimetric analysis and cone calorimetry. Pyrolysis properties (onset temperature, temperature of maximum mass loss rate, and mass residue) and reaction‐to‐fire properties (ignition time, heat release rate, mass loss rate, and smoke release rate) were determined and used for a preliminary assessment of thermal stability and flammability hazards. Additional indices, for ignition and thermal behavior (effective heat of combustion, average smoke yield, and smoke point height, heat release capacity, fire hazard parameter, and smoke parameter, were calculated to provide a more advanced assessment of the hazards in a wind turbine. Results show that pyrolysis of transformer oil, lubricating grease, hydraulic oil, and gear oil occur in the range of 150°C to 550°C. Lubricating grease and transformer oil show the higher and lower thermal stabilities with maximum pyrolysis rate temperatures of 471°C and 282°C, respectively. The measured relation between ignition time and radiant heat flux agrees well with Janssens method (a power of 0.55). The aforementioned indices appear to provide a reasonable prediction of performance under real fire conditions according to a full‐scale fire test documented by Declercq and Van Schevensteen. The results of the study indicate that transformer oil is the easiest to ignite while lubricating grease is the most difficult to ignite but also has the highest smoke production rate; that transformer oil has the highest heat release rate while gear oil has the lowest; and that the fire hazard parameter is the highest for transformer oil and the smoke parameter is the highest for lubricating grease. The potential of this type of work to design safer wind turbines under performance‐based approaches is clearly clarified.     

Synthesis and characterization of vinyl‐polyhedral oligomeric silsesquioxanes‐reinforced silicone resin with three‐dimensional cross‐linking structure

A novel thermal stability and highly transparent silicone resin‐type material was prepared via hydrosilylation of vinyl‐polyhedral oligomeric silsesquioxanes (POSS)‐grafted methylhydrosilicone oil and vinylmethylsilicone oil in the presence of Karstedt catalyst. The morphology, mechanical property, thermal stability, optical transmittance, thermal‐oxidation resistance of the vinyl‐POSS‐reinforced silicone resins were systematically investigated. Scanning electron microscopy showed that the vinyl‐POSS‐reinforced silicone resins had good compatibility with polydimethylsiloxane (PDMS) systems. The mechanical analysis and thermo gravimetric analysis indicated that the mechanical properties and thermal stability increased with increasing quantity of vinyl‐POSS. However, the optical transmittance increased with the increasing amount of vinyl‐POSS rather than decreased. In addition, the incorporation of vinyl‐POSS did not improve the thermal resistance of the PDMS polymers. The product has the potential application for LED packaging. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42187.     

Oxidation stability of methyl esters studied by differential thermal analysis and rancimat

The oxidation stability of methyl esters derived from fresh rapeseed oil and waste frying oil, used as alternative biodiesel fuels, both distilled and undistilled, unstabilized and stabilized by pyrogallol and BHT, was studied by differential thermal analysis (DTA) under nonisothermal conditions at various heating rates and by the Rancimat test under isothermal conditions at 110°C. The results obtained by both techniques are compared. Both techniques show that oxidation stability increases considerably with the addition of antioxidants and that pyrogallol is very efficient. Distillation of the methyl esters prepared from rapeseed oil decreases their oxidation stability, obviously owing to the removal of natural antioxidants. The stability of methyl esters prepared from the waste frying oil is determined mainly by the history of the oil. From the DTA measurements, the kinetic parameters of an Arrhenius-like equation describing the temperature dependence of the oxidation induction period were obtained. The parameters enable one to assess the protective factor of antioxidants for temperatures outside the measuring region, estimate the residual stability, and model the process of biodiesel oxidation under nonisothermal conditions.