| dc.description.abstract | The trend in the applications of biomedical has been increasing for biodegradable
implants material and the performance of an implant is highly related to the properties
of the material. Relying on an excellent properties in high mechanical strength, metallic biomaterials is preffered to assist with repair or replacement of bone tissue that has become diseased or damaged. However, previously metallic biomaterials (stainless steel(316L), cobalt chromium alloy (Co-Cr-Mo and Co-Ni-Cr-Mo) and titanium alloy
(Ti6Al4V)) are limited in terms of degradability and the presence of long term implants
will leads harmful effect to human body due to mismatch between modulus of implant
materials and surrounding bone tissue. Thus, magnesium (Mg) alloy is attractive to
serve as implant materials due to its favorable properties such as, biodegradability and
biocompatibility, its mechanical strength comparable to natural bone and light weight.
Recently, porous material have attracted significant attentions in biomedical
applications. The application of porosity into the implant will reduce the mismatch
between metallic materials and surrounding bone tissue, as the porous structure able to
provide stable biological fixation and enhance bone ingrowth through porous network.
The present study was carried out to develop porous Mg alloy from elemental powder
(Mg alloy and ammonium bicarbonate (NH4HCO3) through powder metallurgy method
based on the space holder technique. This technique utilized two phase of sintering
process which is to heat treated the sample at low temperature to burn out the space
holder to create pores and eventually sintered at high temperature. The aims of this
research are to investigate the effect of processing parameters on the porosity, density,
microstructure and mechanical properties of fabricated porous Mg alloy body. An in
vitro test was conducted using simulated body fluid (SBF) solution to determine the
corrosion and biodegradable behavior of fabricated porous Mg alloy. A design of
experiment (DOE) using Taguchi method was initially used to determine the effect of
processing parameters (sintering temperature, heating rate and sintering time) on the
mechanical performance of porous Mg alloy and the desired setting parameters to set up
the experiment. It was found that sintering temperature contribute to the highest
percentage followed by heating rate and sintering time. Higher sintering temperature, on
the other hand, leads to a better mechanical performance of porous Mg alloy which is
comparable to the cancellous bone. This observation is supported by compression,
hardness, microstructure and x-ray diffraction (XRD) analysis. It should be noted that
the range of compressive strength (1-15MPa), pore size (200-500μm) and porosity
percentage (42%-64%) exhibited in this study for the fabrication of porous Mg alloy
showed the typical range of values noted for materials used in biomedical applications.
In vitro test demonstrated the ability of porous Mg alloy to degrade gradually under pH
control. These findings suggest that, porous Mg alloy is suitable for biomedical
applications. | en_US |
