Biomedical Engineering – From Theory to Applications

Nanocrystalline Thin Ceramic Films Synthesised by Pulsed Laser
Deposition and Magnetron Sputtering on Metal Substrates for Medical Applications
In our study, residual scratch tracks were observed by SEM and compared to the experimental
load-displacement curves during scratch to get access to the tribological properties of the
deposited bioceramics in function of the used processes of elaboration (MS or PLD).
As observed for MS and PLD 5 samples, the failure and then detachment of the Al2O3
coating result in a abrupt changes in load-displacement curves, shown in Fig. 14(a-b), that
show that critical load were reached. This is characteristic of an important release of an
elastic energy during the propagation of cracks into Al2O3 films and then in the interface
between the film and the underlying substrate, yielding to delamination. By contrast for the
PLD 6 sample (Fig. 14c), no change in the hT versus FN curves is observed, proving that no
ductile-brittle transition occurs for the tested normal load range. Same trend was observed
for the PLD 4 sample but not presented here.
Fig. 14. Penetration depth as a function of the applied load during scratch measurements
numbered 1 to 4 for (a) MS and (b-c) PLD 5 and PLD 6 samples.
SEM observations (Fig. 15), showing the scratch morphologies, clearly indicate that the
initiation of failure occurs at the beginning of the scratch experiments for sample PLD 5
where partial cone track is initiated at the trailing edge of the spherical indenter, rapidly
followed by delamination process of the Al2O3.
Fig. 15. SEM micrographs of the residual groove of scratch experiments 4 for the MS and
PLD Al2O3 coatings
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