Improvement of polymer properties for powder bed fusion by combining in situ PECVD nanoparticle synthesis and dry coating

Abstract

Polypropylene (PP) powders are coated with silica nanoparticles in a fluidized bed to improve the flow behavior of the powders and the processability in powder bed fusion. The nanoparticles are produced in situ via dusty plasma‐enhanced chemical vapor deposition (PECVD) in an atmospheric‐pressure Ar/O2 plasma jet fixed at the distributor plate of the fluidized bed. Hexamethyldisiloxane is used as a precursor of the nanoparticles. The influence of the oxygen concentration in the plasma gas and the number of treatment cycles on the chemical composition of the nanoparticles, the amount of nanoparticles deposited, and the flow properties of the coated PP powders is investigated. The chemical composition of the formed silica particles is determined by X‐ray photon spectroscopy and infrared spectroscopy. The results reveal that the composition of the nanoparticles is SiOxCy, that is, the portion of organic residues introduced by the precursor can be controlled by changing the oxygen concentration in the plasma gas. The mass of nanoparticles deposited on the polymer powder's surface, as determined by inductively coupled optical emission spectroscopy, shows a linear dependence of the number of cycles and the oxygen concentration in the plasma gas. A considerable improvement of the flow behavior of the PP powders is observed after PECVD treatment.

Enhancing Photoelectric Powder Deposition of Polymers by Charge Control Substances

“…This is not surprising, as more guest particles act as spacers between the host particles. It is interesting to note that the improvement in flowability does not increase linearly with the further addition of guest particles, which often is shown [ 11 ] and, therefore, expected up to a maximum flowability. The measured flow factors (ffc) of the formulations are very similar.…”

“…The most widely used polymer in L-PBF is currently polyamide 12 with about 90% of the market share [ 2 ]. Many other materials such as polybutylene terephthalate [ 3 , 4 ]; polyethylene terephthalate [ 5 ]; polyamide 11 [ 6 , 7 ]; polyether ether ketone [ 8 , 9 ]; polystyrene [ 10 ]; and polypropylene (PP) [ 11 , 12 ]; as well as polymer composites, for example, polybutylene terephthalate—polycarbonate [ 13 , 14 , 15 ] are used. However, not all have made it to market maturity yet due to the high demands on the powder properties, such as good flowability and a narrow particle size distribution.…”

Dry powder coating in additive manufacturing

“…By formation of composite particles, i.e., adhesion of nanoparticles acting as asperities on the host microparticles, the total vdW particle-particle interaction forces are considerably reduced (Zhou et al, 2003) and, thus, flowability is enhanced. The schematic in Figure 1A depicts coating of host particles with individual guest nanoparticles e.g., by coating of microparticles in the gas phase with in situ formed nanoparticles (Gómez Bonilla et al, 2021a). However, if dry coating is performed with fumed oxides, the added guest particles are mostly agglomerated.…”

Complicated streamer dynamics in petal‐like patterns formed on the substrate downstream of an argon plasma jet

“…The atmospheric pressure plasma jet, which can produce various reactive particles, offers a chamber‐less delivery of downstream reaction chemistry. [ 1,2 ] Due to these advantages, the plasma jet has great potential for applications spanning from biomedicine, [ 3,4 ] biocatalyst, [ 5 ] nano‐material synthesis, [ 6 ] surface modification, [ 7,8 ] to many other fields. [ 9,10 ]…”

“…The atmospheric pressure plasma jet, which can produce various reactive particles, offers a chamber-less delivery of downstream reaction chemistry. [1,2] Due to these advantages, the plasma jet has great potential for applications spanning from biomedicine, [3,4] biocatalyst, [5] nano-material synthesis, [6] surface modification, [7,8] to many other fields. [9,10] Plasma jet fed with inert gas normally operates in a streamer regime, [11] which is not the same as traditional positive streamer discharges, but features as composed of a plasma bullet propagating with a velocity of 10 3 -10 6 m/s.…”