Page 42 - May

NEW TECHNOLOGY

The use of plasma in numerous technological processes is based on the following effects:
● thermal and gas-dynamic properties of plasma flows;
● presence and effect of a directed flow of ionized and excited particles;
● emission of infrared, visible and ultraviolet radiation;
● ozone formation;
● presence of low-frequency and high-frequency plasma pulsations;
● inhomogeneity of the temperature distribution and the structure of the plasma flow;
● mixing of turbulent plasma flow with cold ambient gas;
● interaction of the plasma flow with the surface of materials, which always contain ionized dust
particles, a layer of fat and water molecules, an adsorbed layer of oxygen anions and neutral
air molecules.
Let us consider some examples of the use of plasma technologies in the quality of resource-
saving processes depending on gas discharges, associated with the formation of plasma.

Spark discharge
When an electric current passes through a gas, a spark discharge arises, which exists
at atmospheric pressure and is accompanied by a characteristic sound effect - the "crackle" of
a skipping spark. This type of discharge is most effective is used to apply functional coatings
in air when the electrode contacts the product, as a result of which the electrode consumable
material is transferred and deposited onto the surface of the product. This technology is called
electrospark alloying (electrospark or plasma-spark deposition of coatings) [2]. In this case,
a plus is applied to the electrode (Fig. 1) from the source of the pulse generator, and to the
product - minus from the source.

Anode

Cathode

Fig. 1. Schematic diagram of plasma-spark deposition of coatings, where 1 - current pulse generator; 2 - vibrator; 3 -
electrode; 4 - product; 5 - capacitor; 6 - resistance.

42 Stanochniy park