Page 333 - Handbook of Materials Failure Analysis

330 CHAPTER 13 A concise filtergram wear particle atlas

500µm 100µm
(a) (b)
FIGURE 13.26
The particles mixture oxide scales (200 ): (a) a particle with partial red oxide scale and partial
black oxide scale; (b) a particle with partial black oxide scale and partial red oxide scale.

100µm 100µm
(a) (b)
FIGURE 13.27
The red oxide crystals (like the rust) growth on a wear particle surface (100 ): (a) under white
reflected light; (b) under polarized reflected light.

the lubrication system. Hence, routine oil analysis was a part of the condition mon-
itoring program.
When the Karl Fisher method detected the high level of moisture content
(3970 ppm) in a sample, various color oxide wear particles had also been found
in the oil sample. Figure 13.29 shows the fatigue wear particles with multi-oxide
scales, coloring from yellow to dark brown.
Some tiny red oxide particles (L<10 μm) had also been found in filtergram
(Figure 13.29). Under the polarized reflected light, the red oxide particles remain
their colors and brightness (Figure 13.30b).These tiny red oxide particles could be
broken down from the red oxide scale which had been fully oxidized.