Biomedical Engineering Reference
In-Depth Information
Ti
Ca
P
O
Rt
Rs
Rc
0
100
200
300
400
500
Depth (nm)
FIGURE 1.5
SIMS composition depth profile analysis of HA-Ti6Al4V interface. Three regions can be divided for cross sec-
tions: coating region (Rc), a transitional region (Rt), and substrate region (Rs). Within the transitional region,
Ca and P concentrations decrease drastically from the coating toward the substrate, while the O concentration
decrease gradually toward the substrate; Ti concentration increases gradually from transitional region to the
substrate.
region (Rt) has a thickness of about 85 nm, and within the transitional region, the Ca and P
concentrations decrease drastically toward the substrate, whereas O element decreases
gradually from the coating region (Rc) to the substrate region (Rs), and the concentration
of Ti element increases gradually from the transitional region (Rt) to the substrate region
(Rs). It can be speculated from the existence of the transitional region and the distribution
of the elements along the cross section that certain Ti-P-Ca-O compounds have formed
at/near the interface (Montenero et al. 2000; Hsieh, Perng, and Chin 2002).
Mechanical Properties of Sol-Gel Derived HA Coating
Pull-Out Tensile Adhesion Strength and Interfacial Shear Strength
In view of the successful implantation as well as long-term stable performance, mechani-
cal properties are important for HA-coated metallic implants. Among all the mechani-
cal properties required, adhesion strength (or bonding strength) between the coating
and metallic substrate is the most important property for those load-bearing implants.
Two kinds of pull-out based methods are widely used to evaluate the adhesion strength:
uniaxial pull-out tensile test method (as shown in Figure 1.6a) for the determination of
tensile adhesion strength and shear pull-out test (Figure 1.6b) for the measurement of
shear adhesion strength (Zhang et al. 2008; Ma, Wong et al. 2003; Implants for Surgery-
