Page 345 - Handbook of Materials Failure Analysis

342 CHAPTER 13 A concise filtergram wear particle atlas

(a) 100 µm (b) 100µm

FIGURE 13.46
The friction polymer particles (200 ): (a) a friction polymer particle from a new oil
sample; (b) a color friction polymer particle from a gas turbine oil sample.

(a) 100µm (b) 200µm

FIGURE 13.47
The friction polymer fiber particles (200 ): (a) a friction polymer fiber particle from a gearbox
oil sample; (b) a friction polymer fiber particle from a gas turbine oil sample.

12.4 PSEUDO-METAL WEAR PARTICLES
Some varnish particles would appear to be shining due to their angles of orientation
on the optical microscope. In this case, the varnish particles resemble to metal wear
particles. This type of varnish particles is designated as pseudo-metal wear particles.
Figure 13.56a was a pseudo-metal wear particle, which resembles to a metal wear
particle with dark oxide film. However, gentle touching by the tip of a needle can
fragment this particle (Figure 13.56b). Actually, the particle was a brittle varnish
in which some minute metal wear particles were embedded. Hence, the varnish par-
ticle would behave like steel wear particle under the magnetic field. However, this
type of pseudo-metal wear particles should not exist in ferrogram because they would
be fragmented by the micropump in the ferrograph instrument.
Figure 13.57 shows another type of pseudo-metal wear particle. This particle was
from a gas turbine seal oil sample. At 100 magnification (Figure 13.57a), the