Page 322 - Handbook of Materials Failure Analysis
P. 322
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.