A multi-functional micro-arc plasma spraying system was developed according toaerodynamics and plasma spray theory.The soft switch IGBT(Insulated Gate Bipolar Transistor)invert technique,micro-computer control technique,convergent-divergent nozzle structure andaxial powder feeding techniques have been adopted in the design of the micro-arc plasma sprayingsystem.It is not only characterized by a small volume,a light weight,highly accurate control,highdeposition efficiency and high reliability,but also has multi-functions in plasma spraying,weldingand quenching.The experimental results showed that the system can produce a supersonic flame ata low power,spray A1203 particles at an average speed up to 430 m/s,and make nanostructuredAT13 coatings with an average bonding strength of 42.7 MPa.Compared to conventional 9Mplasma spraying with a higher power,the coatings with almost the same properties as those byconventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with alower power plasma arc due to an improved power supply design,spray gun structure and powderfeeding method.Moreover,this system is suitable for working with thin parts and undertaking onsite repairs,and as a result,the application of plasma spraying will be greatly extended.
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