Biomedical Engineering Reference
In-Depth Information
implants, the decrease of modulus of elasticity is very favorable.
Materials for such implants should have a modulus of elasticity as
close as possible to the modulus of elasticity of bone.
Fracture behaviors vary with the rise of HA content (Fig. 7.6)
[4]. In the HA rich composite, HA matrix presents intergranular
fracture without macroscopic plastic deformation. Most Ti particles
protruding from the fracture surface are intact and HA matrix has
numerous cracks and large pore left behind due to the pull-out of
titanium particles. This conirms that the HA matrix is very weak
and the pull-out of titanium particles is result of crack propagation
along the interface, which indicates the interface bonding appears to
be weak. In contrast, in the Ti-rich composite, the fracture behavior
is controlled by Ti matrix and many pores among the Ti particles can
also be observed.
Figure 7.6
SEM fractograp of different composition regions in HA-Ti
microcrystalline material with: (a) 20, (b) 40, (c) 80, (d) 100
vol% Ti [4].
7.2.3 CorrosionProperties
One of the main factors for determining the suitability of a
biomaterial is corrosion resistance, which is very closely linked to
biocompatibility. Corrosion of implants may lead to pathological
changes in the body, caused by changing the chemical composition
of tissues. Initially, the corrosion resistance is determined mainly
