Hydrothermal Crystallization with Microstructural Self-Healing Effect on Mechanical and Failure Behaviors of Plasma-Sprayed Hydroxyapatite Coatings - Biological and Biomedical Coatings: Processing and Characterization - page 258

Steam pressure
gauge

Valve

PID Controller

Steam

HA coating
specimens

Heater

DI water

FIGURE 6.13
Schematic apparatus of HA-coated specimens within autoclave (Parr 4621) for hydrothermal treatment.

70%-85%) compared with the 600°C to 800°C heat treatments in the air or in vacuum (the
IOC is about 71-80%, calculated from Figure 6.7) [120]. Since the OH − groups can promote
the reconstitution of ACP into crystalline HA [172], therefore the saturated steam-pressure
atmosphere of the hydrothermal treatment can significantly improve HA crystallization
and effectively eliminate ACP through the replenishment of OH − groups.

200°C-12 h

200°C-6 h

200°C-3 h

150°C-12 h

150°C-6 h

150°C-3 h

100°C-12 h

100°C-6 h

100°C-3 h

Plasma-sprayed HACs

28 30 32 34 36 38

2 θ (deg)

FIGURE 6.14
X-ray diffraction patterns of various hydrothermally treated HACs (HT-HACs).