Plasma torch nozzle wear after reverse-polarity cutting of aluminum alloys

The paper studies the layer degradation on the nozzle and electrode surface of plasma torches operating at a current with applied reverse polarity. AA5056 and AA2024 aluminum alloy sheets are used for plasma cutting. It is demonstrated that the surface of the nozzle channel and discharge chamber of the plasma torch are covered with the aluminum layer, that can be attributed to its evaporation in the cutting zone. Copper oxides and insignificant aluminum traces are observed on the surface of the discharge chamber and electrode channel. These copper oxides can almost completely block the water injection in the channel making it unusable.