: Plasma projection

Plasma is generally considered the fourth state of matter.

Why Plasma?

Plasma, in its normal state, a gas composed of electrically neutral molecules, does not conduct electricity. By subjecting a gas to high temperatures, it is possible to dissociate its constituent molecules and then ionize the gas, i.e., separate the electrons carrying negative charges from the nuclei carrying positive charges. Applying an electrical potential to the gas therefore allows an electric current to flow between the anode and the cathode, thus maintaining an electric arc.

In the Plasma process, the anode and the cathode between which the arc strikes are constantly cooled. The arc, initiated by high frequency, is maintained by a low-voltage current source in a flow of plasma gas. The high energy delivered by the source allows a temperature of around 50,000°C to be reached at the cathode. However, this temperature will drop rapidly during projection. The substrate will never heat above 120°C.

The plasma gas undergoes considerable expansion (more than 100 times its volume). It is blown at high speed by the anode nozzle. Outside the nozzle, it gradually returns to its normal state.
However, it remains at a very high temperature, and the resulting speed allows for the projection of highly molten alloys at very high kinetic energy.