Apparatus for producing superfine powder in spherical form

Claim 1

Apparatus for producing superfine spherical powder of diameter of about 5-30 pm from molten multifilaments formed from a molten stream of a metal or ceramic material, comprising a container including an upper gas space, a gas feed inlet, a material inlet, and an outlet for gas and molten material; an axially elongated propellant gas feeder funnel of substantial length extending within said upper gas space to said outlet, said funnel tapering to a zone of most narrow cross-section and defining a rotationally symmetrical Laval nozzle at said outlet, said funnel being formed of a heat conductive refractory material; gas feeding means for feeding a gas, which is nonreactive with the molten material, through said funnel and through said Laval nozzle in a laminar flow exceeding a supersonic rate downstream of said zone of most narrow cross-section; molten material feeding means for feeding a stream of molten material through at least a lower part of said funnel to said Laval nozzle which stream then separates into molten multifilaments downstream of said zone of most narrow cross-section, said molten material feeding means comprising a molten material reservoir having a sidewall tapering to an outlet through which the molten material passes as a stream, said molten material outlet being within and spaced from at least a lower part of said funnel and being spaced above the level of said Laval nozzle; and means for superheating the molten material stream as it passes through at least said lower part of said funnel and said Laval nozzle from the side opposite the molten material reservoir and radiating heat from said funnel and said nozzle to said molten stream prior to stream separation into molten multi-filaments.