At present, 3D printer technology is applied in different fields. Recently, British and German researchers have used 3D printer to explore a new angle, namely screw jet, which is a capacitively coupled RF plasma with double helical electrodes.

In a recent paper, Helicopter: An Innovative Plasma Source for New Generation Additive Manufacturing (3D Printing), the researchers compared laser sintering with their new method, which is digitally manufactured by plasma jet melting powder. This method uses spiral filaments and can be based on materials. The angle or "helicity" of the material is rotated.

[Laser sintered polyamide sphere L1. Photographs of surface morphological details at low (b) and high (c) magnification obtained by secondary electron scanning electron microscopy (a)]

"To provide a proof of principle, the helical jet method was chosen to treat polyamide 12 (PA 12) because PA12 is widely used in least squares methods," the researchers said.

PA 12 is the most common polymer in LS, because of its mechanical properties and good sintering thermal properties, it has high reproducibility for low temperature process, but there are still challenges in efficiency, as well as problems such as elongation at break, porosities leading to failure and low ductility. The researchers studied the following materials:

PA2201 (1)
PA2200 (2)
PA2221 (3)

The main differences between these powders lie in their processability and part performance. The common characteristics of PA 12 have been used to simulate particle heating: density of bulk materials is 1.01 g/cm 3, thermal conductivity is 0.51 W/(m.g), specific heat capacity is 1.75 J/(g.g). It is noteworthy that the mass density varies according to its form (powder or volume). Therefore, the specified density of the powder is 0.93 g/cm 3 (PA1 and PA2) and 0.97 g/cm 3 (PA3).

The sample was printed in 3D on an EOS Fumiga P100 least square system with default parameters. The helical jet engine is powered by argon through a radio frequency power supply connected to two double helical electrodes.

[Specification for plasma source and deposition conditions in plasma printing of polyamide 12]

A bunch of powder is fed into the plasma, and the momentum of the gas forces the particles through the plasma column. Electrodes perpendicular to the filament "accelerate filament sliding in the new plasma source"

"Discharge HS imaging experiments confirm that no filament is formed in the helical jet stream, but a uniform glow discharge column is formed in the tube. Only radio frequency power frequency-induced transmission modulation still exists, "the researchers said.

[In the three-dimensional graph (a) of x-z cutting at y = 0 (b) and X-Y cutting at z = 5.4 mm (d), the predicted electric field of jet cross-section is limited by a circle of rotation of two electrodes. The symbols in (A) denote the equal surface of constant electric field strength | E | equal to 102 KV/m (A), 130 KV/m (B) and 174 KV/m (C1 and C2). The experimental observation shows the axial image taken by high-speed camera P1-MAX4 with exposure time of 3 ns (c) and the 1/80 s side photograph taken by Canon EOS 600D (e).

Experiments show that the heated powder will cause the melting surface temperature and the core temperature to be lower. The team interpreted this as a "self-regulating effect" in which the installation temperature and the resulting evaporation would cause the plasma to "quench" and drop the particle temperature below the melting point.

The researchers concluded: "This effect leads to a combination of morphological features during slow and low-temperature sintering, and enables perspective plasma printing of three-dimensional objects with similar material properties, as shown by scanning electron microscopy and chemical analysis."

"On the basis of feasibility experiments and modelling, it seems possible to use helicopters to speed up the plasma manufacturing process to about 1 cm 3/min, although further work is needed to transform helicopters into full-amplitude-modulation tools, such as the introduction of continuous powder feeding systems and computer control. "

[Photos of helicopters (a) and infrared thermal imaging (b). The high-speed infrared camera focuses on the area marked "zoom" for infrared measurement of particle temperature (compared with Figure 4). High Speed Infrared Ray)

With the rapid development of 3D printing technology, 3D printing has played an important role in a large number of technologies, hardware, software and materials. Nowadays, with the use of different gases, 3D printing plays an increasingly important role in chemistry.

[Temperature Dynamics of Particles. After T1 = 6.6 x 104s (a) and T2 = 9.3 x 103s (b), the particle and gas temperatures obtained by heat transfer simulation at the background temperature of 350 degrees C; high-speed infrared thermal imaging of particles in the effluent at 2,000 feet/second: particle temperatures from the scaling region shown in Fig. 3b (c) to track the movement of a single particle (d). Note that in (c) and (d), particles of different sizes are caused by the focusing of infrared imaging optical devices on the jet axis. The size of out-of-focus particles is different and the temperature is incorrect.