两种航空润滑油高温氧化条件下抗泡性能对比分析

Comparative Analysis of Anti-foaming Performance of Two Kinds of Aviation Lubricating Oils under High-temperature Oxidation Condition

为探讨润滑油在高温高压等苛刻工况下的抗泡性能,以某型国产航空润滑油和进口酯类航空润滑油为研究对象,采用高温模拟氧化装置在175~290℃下进行氧化试验,测定不同温度下氧化后油样的100℃运动黏度和酸值,利用GC/MS分析油样氧化组分和主要产物,并分别对高温氧化油样的泡沫特性和空气释放值进行测定。试验结果表明:2种航空润滑油的黏度随着氧化温度的升高先增大后减小,且均在250℃达到黏度的最大值,但进口油由于极性分子间作用力的存在,其黏度值更加稳定;进口油在氧化温度过高时发生水解和热氧化,导致其酸值在高温下急剧增大,因而腐蚀性明显差于国产油;国产油在起泡倾向和空气释放性能方面均比进口油差,这是由于国产油中的PAO分子的表面聚合以及高温氧化条件下表面活性吸附层的形成,均增大了起泡倾向,并延长了空气释放时间,进而导致抗泡性能变差。

The oxidation tests of a certain type of domestic aviation lubricating oil and a imported ester aviation lubricating oil were carried out in the high temperature simulation oxidation device under the oxidation temperature from 175 ℃ to 290 ℃,to study the antifoaming property of lubricating oil under high temperature and pressure.The kinematic viscosity at 100 ℃ and acid value of the oil samples after oxidation at different temperature were measured,the oxidation component and main product were analyzed by using GC/MS,and the high temperature oxidation bubble characteristics and air release value were determined.The results show that the viscosity of two kinds of aviation lubricating oils is first increased and then decreased with the increase of oxidation temperature,and it reaches the maximum at 250 ℃.The viscosity of the imported oil is more stable due to the existence of polar intermolecular forces.The acid value of imported oil is increased sharply at high temperature due to hydrolysis and thermal oxidation when the oxidation temperature is too high,so its corrosion is worse than that of domestic oil.The foaming tendency and air release performance of domestic oil are worse than that of imported oil,this is due to the surface polymerization of PAO molecule of domestic oil and the formation of surface active adsorption layer under high temperature oxidation conditions,which increase the foaming tendency and prolong the air release time,resulting in the deterioration of anti-foaming performance.