Page 158 - IJB-9-3

International Journal of Bioprinting LPBF of AKM/PEEK biological composite

Table 2. Thermal performance parameters tested by the DSC
ω (AKM = 0 wt%) ω(AKM = 5 wt%) ω(AKM = 10 wt%) ω(AKM = 15 wt%)
T m (°C) 339.55 340.17 339.37 339.67
peak
∆H (J/g) 53.60 52.33 50.40 46.35
m
S (°C) 20.61 20.74 19.54 21.90
w
(300.67–321.28) (300.84–321.58) (301.65–321.19) (299.59–321.49)
T c (°C) 292.79 291.69 291.30 289.49
peak
∆H (J/g) −45.97 −44.21 −42.28 −40.22
c

Figure 4. Tensile strength and Young’s modulus of pure PEEK samples printed at various laser scanning speeds.

decrease with the increase of AKM content. Because mm/s, the tensile strength decreased to 82.87 ± 3.16 MPa.
the melting point of AKM (1450°C) is far higher than The tensile modulus remained nearly consistent when the
the highest temperature that can be achieved during the speed increased to 2000 mm/s but decreased to 3334.03 ±
HT-LPBF process, the AKM powder did not melt during 97.59 MPa when the speed increased to 2400 mm/s. The
the experiment. Therefore, in the composite powder, the changes in tensile strength and modulus are directly
absorbed heat is reduced since the PEEK content decreases, related to the laser energy density. Obvious smoke could
thus resulting in the decrease of the melting enthalpy and be observed during processing when the laser scanning
crystallization enthalpy. This indicates that under the speed was set to 1600 mm/s and 1800 mm/s (i.e., high
same power bed temperature and laser energy density, the laser energy density), which suggests the degradation of
composite powder with higher AKM content will absorb PEEK and explains lower strength tensile under lower
more heat after completely melting, which may lead to a laser scanning speed. While the speed increased from
higher surface temperature during the sintering process 2000 to 2400 mm/s, the reduced laser energy density
and further decomposition of PEEK. was not sufficient to produce enough melting depth and
resulted in a weak interlayer adhesion. At a laser scanning
3.2. Mechanical properties of AKM/PEEK composites speed of 2000 mm/s, the fabricated sample possesses the
fabricated by optimized HT-LPBF process highest tensile strength, and the tiny error bar proves the
The optimization of the HT-LPBF process of pure PEEK performance stability. Therefore, a laser scanning speed
was performed by adjusting the laser scanning speed. of 2000 mm/s was applied to the processing of the AKM/
Figure 4 shows the tensile strength and tensile modulus of PEEK composites as an optimal parameter.
pure PEEK samples fabricated by different laser scanning
speeds. When the laser scanning speed increased from Figure 5a shows the stress–strain curves of samples
1600 to 2000 mm/s, the tensile strength of the sample first fabricated by pure PEEK and composites with different
experienced an increase from 88.37 ± 9.50 to 98.74 ± 0.49 AKM ratios under optimized processing parameters. All the
MPa. When the speed further increased from 2000 to 2400 samples experienced an initial linear elastic deformation,

Volume 9 Issue 3 (2023) 150 https://doi.org/10.18063/ijb.699