Page 36 - MSAM-1-3

Materials Science in Additive Manufacturing Photocatalytic PA6/TiO powder for LPBF
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A B

C D

Figure 9. XRD diffraction curves of PA6, P25-type TiO , and their
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composites. Figure 11. EPMA-WDS element mapping of composite powder shows
the distribution of TiO in particle. (A) Microstructure of composite
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A B powder, (B) Ti, (C) O, and (D) C element distribution. EPMA-WDS:
Electron probe microanalyzer-wavelength dispersive spectrometer.
Laser particle size testing showed that the composite
powder exhibited a good normal distribution, although
there were some small particles below 10 μm. The Dv(10),
Dv(50), and Dv(90) of the composite powder were 31 μm,
48.8 μm, and 72.6 μm, respectively. The AOR values of the
C prepared PA6 and its TiO composite powders are at or
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below 30°, indicating good powder flowability and spreading
properties compared with LPBF-graded PA12 and PEEK
powders [25,26] . Therefore, from the perspective of powder
flowability and particle size distribution, the prepared PA6/
TiO composite powder is suitable for the LPBF process [27,28] .
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In addition, from the perspective of rheology properties,
the studies demonstrated that PA6 has a similar melt
flow index to that of the commercial LPBF-graded PA12
material, indicating suitable melt processing properties
Figure 10. (A and B) Typical microstructure of PA6/TiO composite of PA6 [29,30] . As the DPPC process does not change the
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powder and (C) its particle size distribution.
essential macromolecular structure of the raw material, it
As shown in Figures 10 and 11, the PA6/TiO composite can, therefore, be expected that the rheology properties
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powders were near-spherical, and there was a weak inter- of the prepared powders are suitable for the LPBF
process. From the perspective of thermal properties, the
bonding between the particles. The surface of the powder sintering window of the composite powder is broadened
showed an obvious microporous structure, on which TiO
2 from 19.7°C to 26.6°C compared to pure PA6, showing
was evenly distributed, and the specific surface area of the better processability (Figure 12) [31,32] . With the increase
powder reached 240.5 m /kg. Due to the generation of of the initial melting and crystallization temperatures of
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the porous network morphology, the bulk density of the the composite powder, higher powder bed temperature
powder decreased, as shown in Table 2, especially for the and slower cooling control are required to obtain better
composite powders. On the one hand, this may cause large mechanical properties and dimensional accuracy.
shrinkage during the LPBF process, which is not conducive In general, the PA6/TiO composite powder prepared
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to the control of part accuracy. On the other hand, this is by the DPPC method has great potential to be used for the
very beneficial to the uniform absorption of incident light LPBF process to fabricate 3D photocatalytic material with
and the improvement of photocatalytic efficiency. a characteristic macro-micro porous structure.

Volume 1 Issue 3 (2022) 7 https://doi.org/10.18063/msam.v1i3.14