Mechanical Properties And Bioactivity Of Ti-Nb-Ha Composite Fabricated By Mechanical Alloying
Titanium is the most popular metallic biomaterial for orthopaedic implant owing to their excellent mechanical properties and good corrosion resistance. However, the mismatch of elastic modulus and poor bonding with bones due to its bioinert behaviour has been identified as the major reason that l...
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://eprints.usm.my/47553/1/Mechanical%20Properties%20And%20Bioactivity%20Of%20Ti-Nb-Ha%20Composite%20Fabricated%20By%20Mechanical%20Alloying.pdf |
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| Summary: | Titanium is the most popular metallic biomaterial for orthopaedic implant owing
to their excellent mechanical properties and good corrosion resistance. However, the
mismatch of elastic modulus and poor bonding with bones due to its bioinert behaviour
has been identified as the major reason that lead to the implant loosening and eventual
failure of the implantation. The present work investigates the mechanical performances
and bioactivity of titanium-niobium-hydroxyapatite (Ti-Nb-HA) composite prepared by
mechanical alloying and powder metallurgy. To study effect of HA and Nb , HA and
Nb were varied from 0 to 15 wt.% and 0 to 40 wt.%, respectively. The powders of Ti,
Nb and HA were mixed in a high energy ball mill for 2 hours at 200 rpm and followed
by compaction under 500 MPa and sintering at 1200°C. Due to the brittleness of HA,
the incorporation of HA decreased the compressive strength (1001.24 MPa to 160.94
MPa) and microhardness (300.53 HV to 85.47 HV). Adding HA contribute to the poor
bonding with matrix which is more pronounced to reduce the elastic modulus from
65.10 GPa to 29.91 GPa. With the increasing in HA content, the composite displayed
good bioactivity characteristics evaluation in HBSS for 30 days. The highest bioactivity
was exhibited by composite with 15 wt.% HA due to the highest apatite (3.40%). Factor
affecting the bioactivity are believed to be caused by HA decomposition during
sintering process that produces CaO and CaTiO3. As a result, the presence of these Ca2+
ions increased the calcium concentration and accelerated the apatite growth. Higher Nb
content improved the compressive strength (199.95 MPa to 300.11 MPa) and microhardness (120.97 HV to 269.90 HV) due to solid solution strengthening. However,
the presence of TiO2 and Ti2P decrease compressive strength with 40 wt.% Nb. Apart
from that, the elastic modulus was slightly decreased with the rise of Nb content. The
highest amount of β phase is obtained by 30 wt.% Nb (76%). Increasing in Nb content
to 40 wt.% decreases elastic modulus owing to decrement in β phase as a consequence
of HA decomposition that lead to the formation of TiO2 and Ti2P. The presence of β
phase, high solubility of Ti2P and functional groups of OH- act as favourable site for
apatite growth in composite consisting different amount of Nb. Upon immersion test in
HBSS for 30 days, the highest bioactivity was attained by 30 wt.% Nb and followed by
40 wt.% Nb, 20 wt.% Nb, 10 wt.%. The enhanced of apatite growth in 40 wt.% Nb was
found to be caused by the presence of biocompatibility phases of TiO2 and Ti2P.
Composite with addition of 10 wt.% HA and 30 wt.% Nb displayed the best properties
and holds great potential in providing mechanical support and bioactivity enhancement
in getting similar cortical bone characteristics. |
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