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322    CHAPTER 13 A concise filtergram wear particle atlas
















                          (a)                   100µm      (b)                    200µm













                                                                                  50µm
                          (c)                    200µm     (d)                    50µm
                                                           (d)
                         FIGURE 13.12
                         The catastrophic wear particles from a race car gearbox (200 ): (a) a laminar particle
                         with the color oxide film; (b) a laminar particle with the color oxide film; (c) a sliding
                         wear particle with color oxide film; (d) a laminar particle with blue-green color.



                            Some fatigue wear particles appear as smooth surface on one side and rough sur-
                         face on another side. Figure 13.15a was a fatigue wear particle (L140 μm) found in an
                         oil sample taken from a rolling element bearing lube in a Yankee machine. The smooth
                         side with sliding marks (Figure 13.15a) could be from the rolling-sliding contact sur-
                         face, whereas the rough side (Figure 13.15b) could be from the subsurface fatigue.
                            Oxide film can also form on the fatigue wear particle surface due to the heat
                         affect. Figure 13.16 displays both sides of a fatigue wear particle (L180 μm). This
                         particle was found in an oil sample taken from a rolling element bearing lube in
                         another Yankee machine. As the particle surfaces were rough in both sides, the par-
                         ticle could be generated from the secondary microcrack in the subsurface.
                            Different color oxide films can form on fatigue wear particles. Figure 13.17
                         displays the fatigue wear particles with the color variations. In 13.17a, the major
                         oxide film was straw-yellow. This particle was from a gearbox oil sample.
                         Figure 13.17b–d displays the fatigue wear particles from the roller element bearings
                         in the different Yankee machines. Figure 13.17b was a fatigue wear particle with
                         partial dark blue and partial yellow; Figure 13.17c was a fatigue wear particle
                         (L650 μm) with partial red oxide and partial dark oxide; Figure 13.17d was another
                         fatigue wear particle (L320 μm) with dark oxide.
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