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Materials Science in Additive Manufacturing Photocatalytic PA6/TiO powder for LPBF
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of most photocarriers. This greatly limits the practical composite powders has not been studied in-depth. How to
application range of TiO in research and production . regulate the DPPC process parameters, control the porous
[5]
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From the perspective of material modification, morphology and size distribution of precipitated powders,
different methods have been studied to improve the and prepare PA6/TiO composite porous powders suitable
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photocatalytic performance of TiO , such as semiconductor for LPBF warrants some in-depth investigations.
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compounding, dye sensitization, noble metal deposition, 2. Experimental section
and carbon (C) compound modification [7-10] . Among these
methods, the research on C-modified TiO is particularly 2.1. Materials preparation
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attractive. C-TiO composite can increase the specific Commercial PA6 granules with the trade name Zytel 7331J
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surface area of the material, which is conducive to the were obtained from Dupont, USA. P25 type TiO was
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adsorption of reactive species and the occurrence of a highly dispersed gas phase nanoparticle produced by
catalytic reactions. The composite of C-TiO can also make Degussa Company in Germany. The reaction kettle with
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the photogenerated carrier electrons transfer to C and the capacity of 10 L was used for DPPC powder preparation
reduce the recombination of photogenerated electrons and (Figure 1A), which mainly includes the reaction unit and
photogenerated hole pairs, thereby improving the catalytic its temperature control unit. The schematic of the DPPC
efficiency. method is shown in Figure 1B. First, the reaction kettle was
From the perspective of structural design, the heated to 150°C for 2 h to ensure that the PA6 granules
researchers proposed to prepare a porous TiO were completely dissolved in a high-temperature and
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photocatalytic material to provide a three-dimensional high-pressure alcohol solvent. Afterward, the solution was
(3D) network structure with a large specific surface cooled, and the cooling conditions were controlled so that
area, which is beneficial to improve the photocatalytic the PA6 macromolecules were uniformly precipitated to
efficiency and also provides a way for the rapid transfer realize the nucleation and the coating of TiO . The stirring
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of photogenerated electrons and holes to reduce their speed was 300 rpm. Finally, the reactor was cooled to room
recombination probability . Furthermore, the 3D porous temperature. After discharge, vacuum filtration, drying,
[11]
structure is beneficial to generate light scattering channels and ball milling, the powder materials can be obtained.
and enhance the absorption of incident light. At present, 2.2. Characterization
the preparation of 3D TiO structure mainly adopts ionic
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liquid, nickel foam, and template methods [12-14] . The The powder morphology and element mapping were
prepared 3D porous photocatalytic materials usually have carried out by environmental scanning electron microscope
disordered structures, unavoidable structural defects, (ESEM, FEI Instrument, Netherlands), electron probe
and poor experimental repeatability, which are the main microanalyzer 8050 g, SHIMADZU, Japan, and WDS. The
limitations restricting their applications . specimens were vacuum-coated with platinum for 300 s to
[15]
avoid charging. The morphology and crystalline structure
Laser powder bed fusion (LPBF) additive manufacturing of nano-TiO were analyzed by field emission transmission
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is an effective technique for fabricating 3D ordered porous electron microscope (TEM, Talos F200X, FEI Instrument,
photocatalytic materials [6,16-19] , which provides a new Netherlands) using high resolution TEM (HRTEM) and
idea for solving the problems existing in traditional TiO selected area electron diffraction modes. The particle size
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photocatalytic materials. LPBF also provides an effective distributions of PA6 and composites powers were tested on
technical means for the preparation of ordered porous Mastersizer 3000 (British Malvern). The angle of repose
structures with controllable and repeatable photocatalytic was tested according to the standard ASTM C 1444-00.
properties [20-22] . Although additive manufacturing has Four groups of experiments were performed for each kind
significant advantages in the fabrication of complex ordered of powder, and the diameter of each group was recorded
structures, its application in the field of photocatalysis 4 times and the mean value was taken. The AOR was
is very limited. In this paper, a new polyamide 6 (PA6)- calculated using the following equation:
coated TiO composite porous material is prepared for
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LPBF using the dissolution precipitation polymer coating φ= arc tan 2h/D a (1)
(DPPC) method. As a polymer material, PA6 provides a Where φ represents AOR, h is the vertical distance
carbon source for the carbonization preparation of C-TiO between the top height formed by powder accumulation and
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porous photocatalytic material. Carbon-complexed porous the bottom end of the funnel (38.1 mm in this experiment),
TiO can increase the efficiency of photogenerated carrier and D is the average value of powder packing diameter
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a
separation and thus improve the photocatalytic efficiency. obtained after four groups multiplied by 4 measurements
However, the DPPC method for PA6 and its TiO 2 of each powder. The measurement of powder bulk density

Volume 1 Issue 3 (2022) 2 https://doi.org/10.18063/msam.v1i3.14