Biomedical Engineering – From Theory to Applications

Nanocrystalline Thin Ceramic Films Synthesised by Pulsed Laser
Deposition and Magnetron Sputtering on Metal Substrates for Medical Applications
alternative method to coat metal substrates with HA in order to improve both the chemical
homogeneity and the mechanical properties of calcium phosphate coatings (Nelea et al.,
2006). PLD has successfully produced HA coatings with various compositions and
crystallinity (Arias et al., 2002). Moreover, PLD can synthesize thin HA coatings, adequate
for high fatigue resistance.
Fig. 2. Schematic principle of Pulsed laser deposition (PLD)
4. Experimental details
4.1 Bioinert Al2O3 interlayer
Al2O3 was deposed on stainless steel (grade 304L, Table 1) substrate— square pieces
(1×1×10 mm3). Al2O3 was applied as an inert interlayer to improve the adhesion of bioceramic
films to the metallic substrate. The surgical stainless steel substrate was
mechanically polished and then cleaned with methylene chloride and methanol. A
dynamical pressure of O2 was stabilized inside the PLD chamber and maintained during
the whole deposition cycle. During the deposition, the stainless steel substrate was kept at
200 °C.
Prior deposition the substrates of stainless steel were mirror-polished and then cleaned
ultrasonically in CH2Cl2 and CH3OH. The studied alumina coatings were deposited onto
these substrates by PLD and MS.
Alloy composition
[wt%]
C max Si max Mn max S max Cr Ni N Cu
316 L 0.03 1.0 2.0 0.03 17.5/19.5 8.0/10.0 0.045 ≤0.11
Table 1. Chemical composition in wt of surgical 304L stainless steel
Magnetron sputtered samples were prepared at low substrate temperature (200 °C) by
reactive (O2) direct current sputtering on a planar magnetron. The deposition parameters are
summarized in Table 2. Before deposition, the surface of the substrates was cleaned by a 30
minutes plasma etching.
PLD coatings were produced using an excimer laser KrF* emitting at λ= 248 nm, by 20 ns
pulses at 10 Hz and a sintered alumina target. As for MS samples, the substrates were
maintained at 200 °C during the deposition time. Prior to the deposition, the pressure in the
chamber was 5×10 -6 Pa. Table 3 sums up the deposition parameters.
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