Biomedical Engineering Reference
In-Depth Information
4.22
Detail of the wear track in ZrO
2
-CNF composite - pull-out of CNFs
and smeared transferred film.
4.23
Schematic representation of wear and creation of transferred
carbon film in ZrO
2
-CNF nanocomposite: (a) polished surface before the
wear test; (b) tribofilm formation during the wear test.
due to significantly reduced friction. In Si
3
N
4
-10%CNT, it only reached
values similar to those for Si
3
N
4
-1%CNT.
The micro-mechanisms of wear surface damage were identified by
observation of the wear tracks of composite materials. Microscopic studies
of the worn surface of a ZrO
2
-CNF composite showed pulled-out CNFs
(Fig. 4.22), suggesting the presence of a smeared layer of graphite and
crushed CNFs, the so-called transferred film (Fig. 4.23), which significantly
lowers the friction coefficient, even though a relatively low amount of
carbon (1.07 wt%) was incorporated into the microstructure. The values of
the friction coefficient and wear rates suggest that the CNTs in silicon
nitride based composites were much less effective in creating transferred
