Effect of iron and copper on the thermal oxidation stability of synthetic hydrocarbon aviation lubricating oil

The effect of Cu and Fe sheets on the thermocatalytic oxidation of synthetic hydrocarbon lubricating oils at high temperatures were investigated using various analytic techniques. The fast oxidation rate, low thermal stability, more composition and high relative content of compounds was observed by adding Fe sheets compared to Cu sheets, whereas the high oxidation rate of Cu-bearing oil was observed in the initial heating. With increasing temperature from 230 to 300 °C, the acid number and viscosity of Fe-bearing oil was higher and lower, respectively, than Cu-bearing oil. The oxidation mechanism was attributed to electron transfer and chain reactions of free radical.