Magnetic field-generating nozzle for atomizing a molten metal stream into a particle spray

摘要

A molten metal spray-depositing apparatus employs a magnetic field-generating nozzle for atomizing a molten metal stream into a spray of metal particles. The magnetic driving field generated by the magnetic atomizing nozzle generates eddy currents which produce an induced field in the metal stream opposing the driving field and creating a torque which causes the stream to break up upon exiting the driving field. The nozzle has one of two configurations for generating one of two generic magnetic field geometries. In one configuration the nozzle utilizes a pair of spaced magnetic poles, such as provided by Helmholtz coils, for generating a transverse magnetic field geometry across the stream. In the other configuration the nozzle employs a solenoid coil for generating a solenoidal magnetic field geometry parallel to the stream. Preferably, the magnetic field of each geometry is a high frequency AC field since better coupling between the field and stream occurs and more eddy currents are induced at higher frequency.