Bioceramic Coating on Titanium by Physical and Chemical Vapor Deposition - Biological and Biomedical Coatings: Processing and Characterization - page 315

1100

1050

1000

950

900

: CaO

: CaCO 3

: α-TCP

850

: HAp

: P 2 O 5

800

0 0.5 1.0 1.5

Molar ratio of Ca and P precursor, R Ca/P

2.0 2.5 3.0

FIGURE 7.22
T dep − R Ca/P phase formation diagram of Ca-P-O coatings at P O2 = 0.32 kPa and P tot = 0.8 kPa.

Laser CVD

Laser CVD has been commonly applied to prepare small-scale materials such as thin
films, nanotubes and nanodots, mainly for semiconductor devices. Since the use of a laser
can significantly accelerate chemical reactions, laser CVD can achieve tremendously high
deposition rates at relatively low deposition temperature, which is advantageous for bio-
ceramic coatings on Ti substrates. The present authors first applied laser CVD for biocer-
amic coatings.
The effects of deposition temperature and Ca/P molar ratio on the crystal phase of
Ca-P-O coatings at a laser power of 50W are illustrated in Figure 7.24. (28) Single-phase

(a) (b)

5 µm 5 µm

FIGURE 7.23
Surface morphology of (a) HAp and (b) α-TCP coatings prepared at T dep = 1073 K and P tot = 0.8 kPa.