Biomedical Engineering Reference
In-Depth Information
resistance (Ben Ayed et al., 2006b). It revealed that the mechanical resistance increases with
temperature and reaches its maximum value about 14 MPa (Ben Ayed et al., 2006b).
The mechanical properties of the β-TCP and different TCP - Fap composites depend directly
on the properties of the departure powder (granulometric, crystallinity of the powder,
chemical composition, origin of powder) and on the operative conditions of the sintering
process (temperature, heating time, cycle of sintering, atmosphere) (Ben Ayed et al., 2006b).
Each of these parameters has a direct effect on the final properties of the composite.
Resorbable beta-tricalcium phosphate bioceramic is known for its excellent biocompatibility.
However, it exhibits poor tensile strength. Here, we improved tensile strength of β-TCP
bioceramic without altering its biocompatibility by introducing Fap additives, in different
quantities (13.26 wt %; 19.9 wt %; 26.52 wt %; 33.16 wt % and 40 wt %). In this study, we
showed that the presence of Fap with different amounts in β-TCP matrix improves the
mechanical properties of β-TCP-Fap composites. This result was similar to the previous
report by Bouslama et al. (Bouslama et al., 2009).
Table 4 displays several examples of dense calcium phosphates composites mechanical
properties. The values found by mechanical strength were unequalled with the values in
Table 4, because the authors have used different mechanical modes others than the Brazilian
test. Indeed, many factors influence the mechanical properties such as: initial materials, the
process conditions and annealing treatment. So, it is difficult to compare the results of this
study with those found in literature.
Materials
σ
r
(MPa)
a
σ
f
(MPa)
b
σ
c
(MPa)
c
K
1C
(GPa)
d
References
Fap
14.00
-
-
4.5
Ben Ayed et al.,
2006b
β-CTCP
5.30
-
-
-
Bouslama et al.,
2009
β-TCP
-
92.00
-
-
Kalita et al., 2008
β-TCP- Fap
composites
9.60
-
-
-
Bouslama et al.,
2009
brushite
-
-
32.00
-
Hofmann et al.,
2009
Hap
-
-
5.35
3.52
Balcik et al., 2007
TCP-Hap composites (40/60)
-
-
4.89
3.10
Balcik et al., 2007
Hap-
poly-L-lactic
acid
-
-
100.00
6.00
Gay et al., 2009
composites
a
σ
r
: Mechanical strength (Brazilian test),
b
σ
f
: Flexural strength,
c
σ
c
: Compressive strength,
d
K
1C
:Young's
modulus.
Table 4. Literature examples of dense calcium phosphates composites mechanical
properties.
3.3 Characterization of sintered tricalcium phosphate - fluorapatite composites
After sintering, different techniques characterized the samples: X rays diffraction (XRD),
31
P
MAS-NMR, scanning electronic microscopy (SEM) and infrared spectroscopy (IR).
Composites of -TCP with Fap were pressureless sintered at temperatures from 1100 to
1450°C. The reactions and transformations of phases were monitored with X-ray diffraction.
