A facile route for hydroxyapatite densification with an increased heating rate

- Influence of heating rate on HAp nanorods densification is studied.
- Fully dense material is prepared even with heating rate of 50 °C/min.
- Faster heating influenced microstructural refinement.
- The level of optical translucency is also increased with heating rate.

The densification behavior of hydroxyapatite nanorods prepared by chemical precipitation method in open reactor conditions was investigated by application of different heating rates. The non-isothermal processing was performed with 2, 10, and 50 °C/min up to 1200 °C and yielded fully dense ceramics. The implementation of the higher heating rate provided grain size refinement from micrometer level for the slowest ramp, down to 250 nm in the case of processing with 50 °C/min, without any drawbacks regarding final density. The relative amount of retained structural hydroxyl groups in sintered ceramics was gradually increased with the heating rate. Furthermore, the qualitative level of optical translucency was increased with a higher heating rate which can be explained by the beneficial alignment of HAp nanorods during the fast heating rate processing, achieved microstructural refinement, and higher amount of structural hydroxyl groups.

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