NUST Institutions Library Catalogue

Hydroxyapatite (HAP) is a very promising bio-ceramic as it resembles the mineral composition
of bones and has excellent capability of bonding to bone tissues. It offers high biocompatibility,
nontoxicity and good osteoconductivity. Therefore, it is an excellent choice for use as a bone
substitute and in orthopedic or dental implants etc. However, its use is limited in biomedical
applications specifically load-bearing implants as HAP exhibits poor mechanical properties.
Alumina, known for its excellent mechanical strength and chemical stability, is added in HAP
to enhance the mechanical properties of the composite while maintaining biocompatibility. The
objective of this research is to synthesize and characterize a modified bio-composite with
enhanced mechanical properties and excellent biocompatibility. For this purpose, an AluminaHAP bio-composite is developed with varying weight percent (wt. %) of Alumina. Two
different processing routes, planetary ball mill which is high energy ball milling (HEBM) and
tumbler ball milling i.e. low energy ball milling (LEBM), are adopted to mix the powders, and
their impact on the mechanical properties is studied. The samples were prepared by using
powder metallurgy techniques such as cold compaction followed by high temperature vacuum
sintering process. The microstructure analysis is carried out using characterization techniques
such as XRD, SEM etc. Mechanical testing of the samples is performed to compare the
mechanical properties including density, hardness and compression strength of the sintered
samples. The experimental results indicate that mechanical alloying using high-energy ball
milling technique has significantly improved mechanical properties. Moreover, the mechanical
properties of the bio-composite enhance with addition of Alumina (Al2O3) with the best results
found for composite consisting of 40%HAP-60%Alumina. Overall, this research contributes
towards the understanding of bio-composite materials for biomedical applications and the
potential of HAP-Alumina bio-composite developed via Powder Metallurgy as a promising
material for orthopedic and dental applications.