Figure 4
The
color evolution of the PAO and DIOS oil samples with antioxidants (T501,
T531 and Tz516 mentioned in Experimental Section) after oxidized at
175 oC
Both 928 and 50-1-4Φ aviation lubrication oil have the viscosity of
3 cSt at 100 oC, however, the base oil of two
lubrication oils is quite different. The base oil of 928 aviation
lubrication oil is mainly poly-α-olefin (known as PAO), and the base oil
of 50-1-4Φ aviation lubrication oil is synthetic ester (in this paper is
di-iso-octyl sebacate, DIOS), as shown in Figure 3.
In the same appliance, the PAO and DIOS (both kinematic viscosity of the
base oils is 3 cSt at 100 oC) is comparatively
oxidized at 175 oC for the reasons mentioned before.
The oxidation temperature is maintained at 175 oC
which is coincident with the maximum operation temperature of 50-1-4Φ
aviation lubrication oil. As shown in Figure 4, the oxidized PAO and
DIOS oil samples with antioxidants (T501, T531 and Tz516 mentioned in
Experimental Section) have significant color darkening phenomena after
antioxidants were applied in the pure PAO and DIOS. It should be noted
that the antioxidants T501, Tz516 are used in 928 and T531 applied in
50-1-4Φ aviation lubrication oil, respectively.