Page 156 - IJB-9-3

International Journal of Bioprinting LPBF of AKM/PEEK biological composite

Figure 1. SEM micrographs of (a) PEEK and (c) AKM powders. Particle size distributions of (b) PEEK and (d) AKM powders.
A stable initial decomposition temperature was beneficial corresponding to the peak melting temperature (T m peak ),
to the HT-LPBF process because the increase of AKM and an exothermic peak at around 290°C corresponding
content will not exacerbate the decomposition caused by to the peak crystallization temperature (T ). The initial
c
peak
high-temperature laser action. This allows the process to crystallization temperature and initial melting temperature
remain stable under the same temperature parameters. remain at around 300°C and 321°C, respectively, with
The residual mass fractions of composite powders after the increasing content of AKM. This suggests that the
the complete decomposition of PEEK are 4.96 %, 10.72%, composition of AKM has little effect on the initial processes
and 15.35%, respectively. The mass fractions are very close of crystallization and melting. In the HT-LPBF process, the
to that of the added ratios of AKM, which proves that the powder bed temperature (T ) is required to be kept in the
b
distribution of AKM is uniform. As shown in the primary sintering window (S ), which is schematized by the blue
w
differential curve of Figure 3a, PEEK and its composites area shown in Figure 3b. According to the calculation, the
mainly show a two-stage degradation form. All powders S remains nearly consistent as the AKM content increases.
w
reached a maximum rate in the temperature range of This result indicates that the addition of AKM powder does
619°C–621°C, in which 15 wt% AKM/PEEK powder not change the requirements of temperature control for the
presented a delayed temperature at 621°C. This suggests powder bed in the HT-LPBF process, and will not increase
that the AKM content is beneficial for slightly improving the difficulty of fabrication. On the contrary, the addition
the thermal stability of the composite. of AKM reduces the difficulty of fabrication because the
peak crystallization temperature delay slows down the
The melting and crystallization properties are vital factors part warping. Combined with the results of TGA, it can
to evaluate the HT-LPBF processability of the powders, be inferred that with the increase of AKM proportion in the
which are analyzed through the DSC curves, as shown in powder, the processing temperature can still be set to the
Figure 3b. Specific parameters are shown in Table 2. The same parameter as that of pure PEEK powder. The melting
DSC curves show an endothermic peak at around 340°C enthalpy and the crystallization enthalpy of powders

Volume 9 Issue 3 (2023) 148 https://doi.org/10.18063/ijb.699