This investigation aims at synthesizing and characterizing
a biocomposite
of hydroxyapatite (HA) and titanium (Ti) as a functionally graded
material (FGM) via an economical powder metallurgy route. Ti particles
were produced through drilling and chipping, followed by compaction
and sintering. Ti foams, so obtained, were then infused with varying
volume fractions of HA. The pure Ti foam control sample and the FGM
composite samples were then subjected to various characterizations
to validate their biocompatibility, structural strength, and integrity.
The interface development between the load-bearing Ti implant and
living tissue was resolved through an FGM structure, where the base
of the implant consisted of load-bearing Ti and the outer periphery
changed to HA gradually. HA/Ti specimens of different volume fractions
were tested for density measurements, microstructure, hardness, and
bioactivity. The bioactive behavior was investigated using the potentiodynamic
polarization technique to measure the corrosion rate of the pure Ti
foam (0/100 HA/Ti) and the FGM composite (10/90 HA/Ti) samples in
a simulated body fluid (SBF). The results showed that the hardness
of FGM composites, despite being less than that of 0/100 HA/Ti, was
still within safe limits. The corrosion rate, however, was found to
be decreased by a significant value of almost 40% for the 10/90 HA/Ti
FGM composite sample compared to the pure Ti foam control sample.
It was concluded that the optimum composition 10/90 HA/Ti sample offers
improved corrosion resistance while maintaining a sufficient allowable
hardness level.