The coating of the layers carried out by thermal spraying technology is composed of many thin, overlapping, basically layered particles. When the material is introduced into the spray gun, the particles return the heat energy towards the high-velocity gas and melt into droplets, which receive kinetic energy from the high-velocity gas and move towards the target, where they hit the surface like a split. When in contact with the target surface, the droplet converter heat transfer is conducted to the substrate and returns to the solid, which is the principle of tungsten carbide spraying, and when they are cooled, the quenched tungsten carbide coating can achieve the same effect as supersonic spraying.

Difficulties in supersonic spraying of tungsten carbide

The difficulty in the supersonic spray tungsten carbide processing process is that the structure of the thermal spray coating tends to be porous. Unlike the ordinary high-speed supersonic flame spraying porosity, which is less than 2%, the porosity caused by the characteristics of tungsten carbide spraying coating is expected to be in the range of 5~30%~461, and the porosity of the flame spraying coating may exceed I5%. The magnitude of the 131 porosity depends on the melted state of the spray, and the melting state of the ED particles is deformed in the ability of the impact to bond the structure. 171 When evaluating dielectric breakdown, porosity plays a major role in the amount of voltage that the insulation layer is capable of occupying. If the coating is exposed to moisture, moisture can accumulate within the structural voids, resulting in a lower breakdown voltage. During the tungsten carbide spraying process, the occurrence of IIS conditions can be prevented, and then the packaging can be sealed. The second consideration that cannot be changed is the fact that the void contains air, and the breakdown voltage of air is much lower than that of the parent insulator.

Low temperature standard for tungsten carbide spraying process

The low temperature of the tungsten carbide spray process limits the early thermal spray processing of thermal spray because they are produced by an oxygen flame or arc. Materials with a melting point of 2700°C or higher cannot be sprayed, and attempts to extend the temperature range of the heat source lead to the development of plasma spraying. Plasma is a highly ionized state consisting of molecules, atoms, ions, electrons, and light quantities, and the 18.9J plasma arc torch began to expand around 1958. Plasma torches have TN type types, they are determined by the arrangement between the electrodes of the electric plasma burning, so the non-transfer arc is the arc that occurs between the cathode and the positive anode inside the cathode, and the transfer arc is 10% when the positive electrode is conducted to the outside.

(The article comes from the Internet)