Biomedical Engineering Reference
In-Depth Information
1180°C, 1154°C, 1145°C, 1100°C, 1052°C, 1045°C and 775°C for β-TCP, β-TCP - 13.26 wt%
Fap composites, β-TCP - 19.90 wt% Fap composites, , β-TCP - 26.52 wt% Fap composites, β-
TCP - 33.16 wt% Fap composites, β-TCP - 40 wt% Fap composites and Fap, respectively. The
addition to Fap additive in the matrix of β-TCP decreasing the sintering temperature of the
pure tricalcium phosphate (Fig. 1b-1f). Indeed, the sintering temperature of β-TCP decreases
when the percentage of Fap increases.
T (°C)
0
0
100
200
300
400
500
600
700
800
900 1000 1100 1200 1300 1400
(a)
-5
(c)
-10
(b)
(d)
(f)
(e)
-15
(g)
-20
Fig. 1. Linear shrinkage versus temperature of: (a) β-TCP powder, (b) β-TCP - 13.26 wt% Fap
composites, (c) β-TCP - 19.9 wt% Fap
composites, (d) β-TCP - 26.52 wt% Fap
composites, (e)
β-TCP - 33.16 wt% Fap
composites, (f) β-TCP - 40 wt% Fap
composites, (g) Fap powder.
Differential thermal analysis studies detected out a potential phase change during the
sintering of a different powder used in this study. Fig. 2a shows DTA curve of β-TCP. The
DTA thermogramme shows 2 peaks relatives to the first and second endothermic allotropic
transformation of β-TCP (1290°C and 1464°C). The last endothermic peak, at 1278°C, was
related to a peritectic between β-TCP and pyrophosphate (β-Ca
2
P
2
O
7
). The chemical reaction
was illustrated in the following:
Ca
3
(PO
4
)
2(s)
+ Ca
2
P
2
O
7(s)
→ Ca
3
(PO
4
)
2(s)
+ liquid phase (3)
This was similar to the result previously reported by Destainville and colleagues
(Destainville et al., 2003).
Fig. 2b and Fig. 2g show the DTA curves of β-TCP - 13.26 wt% Fap composites and Fap
powder, respectively. We notice one endothermic peak around 1180°C. This peak may be
due to the formation of a liquid phase, formed from binary eutectic between CaF
2
and Fap
(Ben Ayed et al., 2000). We can assume that fluorite (CaF
2
) was formed as a second phase
during the powder preparation of Fap.
Fig. 2c, 2e and 2f illustrate the DTA curves of β-TCP - 19.9 wt% Fap composites, β-TCP -
33.16 wt% Fap composites and β-TCP - 40 wt% Fap composites, respectively. Fig. 2c and 2f
are practically similar with the Fig. 2a. Indeed, DTA thermogramme of composites shows
also 2 peaks of tricalcium phosphate allotropic transformations.
