Kesan penambahan MgO, Al2O3 dan BaO ke atas hidroksiapatit
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Date
2005
Authors
Noor Hasimah, Marsad
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Abstract
The influence of three additives viz magnesium oxide (MgO), aluminium oxide (Al2O3)
and barium oxide (BaO) on the physical, mechanical and microstructure of
hydroxyapatite (HA) was studied. HA powder was mixed with 1% and 2% MgO (H1M
and H2M), 1% and 5% Al2O3 (H1A and H5A) and 1% and 5% BaO (H1B and H5B).
The powder was uniaxially compacted to form bar-shaped specimens. The specimens
were then sintered at various temperatures (1100-1350C) for 3 hours soaking. After
sintering, the specimens were analysed for physical properties (shrinkage, porosity and
bulk density), mechanical properties (fracture strength), phase analysis (XRD) and
microstructure (SEM). The results showed that MgO slows down the sintering process
of HA. This result has an effect on the microstructure of HA. Both average grain size of
H1M and H2M were smaller than HA. H1M and H2M showed better mechanical
properties than HA. The optimum fracture strength of HA was 68.78MPa whereas the
optimum fracture strength of H1M and H2M were 79.85MPa and 89.69MPa,
respectively. H1A did not show any differences on the physical properties of HA.
However, there was an effect on the microstructure and mechanical properties of HA.
At 1300C, the grain structure of H1A was more homogeneous than that of HA.
Therefore the mechanical properties of H1A were better than HA. The fracture strength
of H1A sintered at 1300C was 85.99MPa. The structure of H5A was more porous
because of the existence of 5%Al2O3 in HA structure. Therefore the fracture strength of
H5A is lower than HA. The optimum fracture strength of H5A is 19.12MPa. H1B and
H5B did not show any differences on the physical, mechanical and microstructure properties of HA. Nevertheless, XRD analysis indicates the presence of Ba-HA phase in
the specimens after sintering at 1100-1300C. This result showed that the cation sites of
HA (Ca2+) can be replaced by Ba2+. The Ba-HA tends to exhibit a better crystallinity. In
conclusion, HA with different additives (MgO, Al2O3 and BaO) clearly show different
effects on the physical, mechanical and microstructure properties of HA.
Description
Master
Keywords
Materials and Mineral Resources Engineering , Hydroxyapatite