Page 323 - Handbook of Materials Failure Analysis
P. 323

320    CHAPTER 13 A concise filtergram wear particle atlas


















                          (a)                  50µm         (b)                    50µm
                         FIGURE 13.9
                         The laminar particles with different colors (200 ): (a) a laminar particle with straw-yellow
                         color; (b) a laminar particle with pink-blue color.













                                                   20µm                           100µm
                          (a)                               (b)

                         FIGURE 13.10
                         The laminar particles (200 ) with partial red oxide surface. (a) a laminar particle with
                         striations and partial red oxide film; (b) a laminar particle with partial red oxide and partial
                         pink oxide film.


                         CASE 1: THE CATASTROPHIC WEAR IN A RACE CAR GEARBOX
                         The race car gearbox operates in extremely harsh conditions due to both high speed and
                         the impact loads. The lubricant for the gearbox was a special oil containing the solid EP
                         additive suspension. The solid EP dispersion can cushion gear teeth for preventing
                         tooth breakage and allow the use of the lower viscosities for the high speed.
                            The special oil had been lubricating the race car gearbox properly. In the racing
                         history, the recorded maximum oil temperature was 94.1 °C. However, another non-
                         solid EP type of gearbox oil was tested in a qualifying racing. The oil temperatures
                         reached to 168 °C during the racing, noticing improper lubrication.
                            After the qualifying racing, the gearbox was stripped down for an inspection
                         (Figure 13.11a). The gear damages were identified (Figure 13.11b). An oil sample
                         from the failed gearbox had been collected for the analyses. Wear particle analysis
                         identified the catastrophic wear. Figure 13.12 displays some of the catastrophic wear
   318   319   320   321   322   323   324   325   326   327   328