Bioceramic Coating on Titanium by Physical and Chemical Vapor Deposition - Biological and Biomedical Coatings: Processing and Characterization - page 320

TABLE 7.4
Apatite Formation Time on Bioceramic Coatings in SBFs

Apatite
Formation(ks) CoatingMethod PhaseofCoating SBF Reference

Thermal CVD HAp Hanks' solution 21.6 (27)

Thermal CVD α-TCP Hanks' solution 1209.6 (27)

Thermal CVD CaTiO 3

complicated surface

Hanks' solution 259.2 (68)

Thermal CVD CaTiO 3

smooth surface

Hanks' solution 3628.8 (68)

Laser CVD Hanks' solution 259.2 (28)

HAp, β-TCP

Plasma spraying HAp Kokubo solution 86.4 (69)

Sol-gel HAp + TiO 2 Kokubo solution 691.2 (70)

formation in Kokubo solution. (71) In CVD, a spatial gap suitable to apatite formation can be
introduced by controlling the surface morphology of the bioceramic coatings.
The relationship between the crystallographic orientation of HAp coatings prepared by
CVD and apatite formation in SBF has been studied. Apatite formation on an HAp coating
oriented to the c -axis (i.e., the 〈002〉 direction) in Hanks' solution was faster than that oriented
to other directions. Preferential apatite formation on the c -face of HAp has been reported in
the immersion test of a highly oriented HAp sintered body in Kokubo solution. (72) Figure 7.30a
and b show the surface morphology of HAp coatings prepared by laser CVD oriented to
the a -axis (i.e., the 〈300〉 direction) after immersion in Hanks' solution for 259.2 and 604.8
ks, respectively. Although the apatite formation rate on the (300)-oriented HAp coating was
not high, apatite formation was observed at hollow places 259.2 ks after immersion and the
whole surface was covered with needlelike apatite crystallites 604.8 ks after immersion.
These results suggest that the hollow places and (002) preferred orientation in bioceramic
coatings enhance the apatite formation in SBF.

(a) (b)

FIGURE 7.29
Surface morphology of HAp coatings prepared by thermal CVD after immersion in Hanks' solution for (a) 3.6 ks
and (b) 21.6 ks.