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In this work, nanosized hydroxyapatite (HA) powder was synthesized via mechanochemical method
by a dry mixture of calcium hydroxide Ca(OH)
2
and di-ammonium hydrogen phosphate
(NH
4
)
2
HPO
4
powders. The effect of mechanochemical process on powder properties was
investigated. Three rotation speeds of 170 rpm, 270 rpm and 370 rpm were chose with 15 hours
milling time respectively. Characterization of nanopowders was accomplished by Fourier transform
infra red (FTIR), X-ray diffraction (XRD) and nanosizer analysis. The green compacted powders
with 200 MPa isostatically pressed were prepared and sintered in atmosphere condition at various
temperatures ranging from 1150
o
C - 1350
o
C. The results showed that the rotation speed affected the
obtained powders where the crystallite size was found increased with rotation speed (9 – 21 nm). In
contrast, the particle size distribution decreased with rotation speed (322-192 nm). The sintering
process has influenced the stability of powder by yielding TCP phase at a lower sintering
temperature, 1150
o
C. However, powder synthesized at 370 rpm has showed a significant hardness,
5.3 GPa after compacted and sintered at 1250
o
C with the relative density of 95%. This phenomenon
is believed to be related with the nanosize powder synthesized at high speed which has contributes
the high strength of the sintered bodies.
Hydroxyapatite (HA) is usually used for a number of biomedical applications in the forms of
granules, blocks, coatings, dense bodies [1-4], for bone augmentation and middle-ear implants [4].
HA also has shown the benefits in therapeutic antitumor vaccine [5] and was useful for drug
delivery and antibiotics [6-7]. It naturally contained in human bone as the crystals within collagen.
The high strength is necessary for the reliable work of an implant in the body [8]. Many
improvements have been made earlier to overcome the limitation of HA in loading application by
controlling microstructures via novel sintering technique or utilization of nano powders [9].
Development of dense HA ceramics with superior mechanical properties is possible if the starting
powder is stoichiometric with better powder properties such as crystallinity, agglomeration, and
morphology. A decrease in grain size to nano scale in dense sintered materials is a desired
parameter to enhance the mechanical and biological properties of HA-based bioceramic materials
[10]. There have been several methods applied in synthesized HA nanocrystalline powder consist of
co-precipitation [6], emulsion/microemulsion [11], sol-gel [12], hydrothermal [13] and
mechanochemical [14]. Mechanochemical is a simple and low cost method compared to others. The
chemical processes occurring during mechanical action on solids became to be more specific and
versatile. Besides, mechanochemical treatment has been recently receiving attention as an
alternative route in preparing materials characterized by better biocompatibility with natural bone
Materials Science Forum Vol. 694 (2011) pp 118-122
Online available since 2011/Jul/27 at www.scientific.net
© (2011) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/MSF.694.118
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
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