偏苯三酸酯基础油的摩擦降解及对抗氧化性能的影响

Tribological Degradation of Trimellitate Esters Base Oil and Its Influence on Anti-oxidation Performance

为研究润滑油在边界润滑条件下的摩擦降解及其对润滑油性能的影响,采用四球试验机考察偏苯三酸三异辛醇酯(TMTO)、偏苯三酸三异壬醇酯(TMTD)以及偏苯三酸三异十三醇酯(TMTT)在边界润滑条件下的摩擦学性能。结果表明:分子结构对偏苯三酸酯在边界润滑条件下的润滑性能有较大影响,链长最长的TMTT的减摩与抗磨性能优于TMTO与TMTD。利用高压差示扫描量热仪(PDSC)及热重分析仪(TGA)研究四球试验前后3种基础油的抗氧化性能及热分解性,并测试摩擦试验前后润滑油的黏度与酸值变化。结果表明:边界润滑条件下的摩擦过程会导致偏苯三酸酯类基础油黏度升高、酸值降低、氧化安定性下降;润滑性能良好的基础油在一定程度上阻止或减缓润滑油本身氧化反应的发生;在边界润滑条件下,偏苯三酸酯一部分在机械剪切及水解作用下分解会生成小分子的化合物,另一部分在氧化作用下聚合生成大分子化合物。

In order to study the friction degradation of lubricating oil and its influence on the performance of lubricating oil,four ball test machine was used to evaluate the tribological properties of tri-isooctyl trimellitate(TMTO),tri-isonony trimellitate(TMTD),tri-isotridecyl trimellitate(TMTD)under boundary lubrication condition.Results show that the tribological performances of the tested oils are highly influenced by the molecular structure.The friction and wear resistance of TMTT with the longest chain length is better than that of TMTO and TMTD.TMTD,which has the longest alkylchain,posses the best friction reducing and anti-wear properties compared with TMTO and TMTD.Pressure differential scanning calorimetry(PDSC)and thermogravimetric analyzer(TGA)were applied to investigate the thermal and anti-oxidation behaviors of the lubricants,and the changes of the viscosities and acid values of the lubricants before and after tribological test were also investigated.Results indicate that the tribological degradation of trimellitate esters has great influence on the viscosity,acid value as well as anti-oxidation properties of the lubricants.The esters with good lubricating performances can prevent or slow down the oxidation process.Under the boundary lubrication condition,some of the trimellitate ester decomposes to the small molecule compounds due to mechanical shearing and hydrolysis,and some of the trimellitate ester is prone to polymerize and generate the high molecular compounds due to the oxidation.