Plasma spray working gas

       1) The choice of plasma working gas mainly depends on the material to be sprayed. The selected gas should have stable performance and no harmful reaction with the sprayed material. Therefore, the plasma working gas must be inert, and argon is usually used. In addition to materials that are susceptible to nitrogen contamination and cause embrittlement, nitrogen is also often used, and hydrogen can be used as a secondary gas.



     2) Gas with high enthalpy should be selected. High enthalpy is especially suitable for spraying refractory materials such as oxides, but too high enthalpy will cause serious ablation of the nozzle. , diatomic gases such as nitrogen and hydrogen are chosen, mainly because these gases have a higher enthalpy than argon or helium at the same high temperature.

     3) Gases that do not chemically interact with electrodes and nozzles should be selected.

     4) The selected gas should be cheap and easy to supply.