Page 321 - Handbook of Materials Failure Analysis
P. 321

318    CHAPTER 13 A concise filtergram wear particle atlas
















                                                  100µm                             100µm
                          (a)                              (b)













                                                 50µm                              50µm
                          (c)                              (d)
                         FIGURE 13.7
                         The wear particles had been subjected to different degree of the press (200 ): (a) a
                         fatigue wear particle from a rolling element bearing; (b) a fatigue wear particle from a
                         compressor; (c) a laminar particle subjected severe press; (d) a laminar particle pressed
                         from a cutting wear particle.


                            During the machine’s operation, some wear particles can be further deformed by
                         the machine component’s rolling and pressing, forming the laminar particles. Hence,
                         the thickness ratio of laminar particles depends on severity of pressing.
                            Figure 13.7 displays the wear particles subjected to different degree of press.
                         Figure 13.7a is a fatigue wear particle from an oil sample taken from a rolling ele-
                         ment bearing. The particle surface had been flattened. Figure 13.7b is a fatigue wear
                         particle from an oil sample taken from a compressor. The cracks on the flat surface
                         indicate severe press. Both particles remained both features of fatigue wear particle
                         (thicker) and laminar particle (flat surface). Figure 13.7c and d are the wear particles
                         from an oil sample taken from a rolling element bearing in a Yankee machine. In
                         Figure 13.7c, the laminar particle had been pressed so severely, forming the big
                         cracks and the holes. Figure 13.7d is a laminar particle originally from a cutting wear
                         particle.
                            Some wear particles lose their magnetic properties although the particles are
                         generated from the low-alloy steel components. The mechanisms of magnetic
                         alternation have not been studied. It could be due to the crystal transformation in
                         the particle formation, such as changing from bcc to fcc, or forming amorphous
                         structures.
   316   317   318   319   320   321   322   323   324   325   326