Page 322 - Handbook of Materials Failure Analysis
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5 Laminar Particles   319












                                                                    EDS




                                            50µm        (b)
                   (a)

                             Label A: SGS Particle TRH75-80
                                            Fe
                                                    Element  Wt.%   At.%
                                                      C K   15.26  45.56
                                                      MnK    1.55   1.01
                                                      FeK   83.19  53.42
                                                      Total  100    100
                               Fe




                              C
                                          Mn
                          (c)    2.00  4.00  6.00  8.00  10.00  12.00  14.00  16.00  18.00  keV
                  FIGURE 13.8
                  A nonmagnetic laminar wear particle from a wind turbine gearbox: (a) under optical
                  microscope (200 ); (b) under ESEM (3000 ), and (c) EDS analysis results indicating low-
                  alloy steel (1.55% Mn) and the results on non-magnetic laminar wear particle indicating that
                  the particle was from the low alloy steel.


                     Figure 13.8a is a nonmagnetic laminar particle which cannot be attracted by a
                  magnetic tip. This particle was found in an oil sample from a wind turbine gearbox.
                  In situ ESEM/EDS (environmental scanning electronic microscope/energy disper-
                  sive spectroscope) analysis results on the particle (Figure 13.8b) to confirm the
                  low-alloy steel, excluding from austenitic (18-8 type) stainless steels.
                     During particle formation, oxide film would form on the particle surface due to the
                  heat affect. The oxide films change the particle colors, appearing from straw-yellow to
                  blue. Figure 13.9 shows two laminar particles with the different colors. The particles
                  were from the oil samples taken from different gearboxes in a paper mill.
                     Generally, red oxide film on the wear particle surface is associated with moisture in
                  theoil[4].Figure13.10displaystwolaminarparticleswithredoxidefilm.Figure13.10a
                  showsalaminarparticle(L50 μm)withthepartialredoxidefilm.Figure13.10bshowsa
                  laminarparticle(L180 μm)withpartialpinkandredoxidefilm.Theparticleswerefrom
                  the oil samples taken from different gearboxes in a paper mill.
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