Nozzle and method for forming microdroplets

Abstract

The invention relates to a nozzle for producing microdroplets of metal using gas flow, to a nozzle for producing microdroplets using electrodispersion, to a combination of a melt spinner for forming elongate metal fibers with a nozzle and to a method of forming microdroplets using at least one of a gas flow and electrodispersion.

1 .- 18 . (canceled) 
     
     
         19 . A nozzle for producing microdroplets of metal, the nozzle comprising a reservoir for molten metal, a nozzle opening for directing the molten metal in a flow direction out of the reservoir and a channel connecting the reservoir with the nozzle opening, wherein the nozzle further comprises an external force generating device configured to apply an external force on a molten metal flow flowing in said channel with a force per unit area generated by the external force generating device at the molten metal being larger than a surface tension of the molten metal. 
     
     
         20 . A nozzle for producing microdroplets of metal using gas flow, the nozzle comprising a reservoir for molten metal, a nozzle opening for directing the molten metal in a flow direction out of the reservoir and a channel connecting the reservoir with the nozzle opening, wherein the nozzle further comprises a gas flow generating device for generating and directing the gas flow to the molten metal through at least one supply opening into the channel, wherein the gas supply opening is located at the nozzle opening, wherein a force per unit area generated by the gas flow at the molten metal is larger than the surface tension of the molten metal. 
     
     
         21 . The nozzle according to  claim 20 , wherein the gas flow generating device is configured to direct the gas flow perpendicular to or at an angle to the flow direction of the channel. 
     
     
         22 . The nozzle according to  claim 20 , wherein the channel comprises two or more supply openings to receive the gas flow from more than one side around the circumference of the nozzle. 
     
     
         23 . The nozzle according to  claim 20 , wherein the gas in the gas flow is air, argon, Helium, N2, Ar2, CO2 or combinations of the foregoing. 
     
     
         24 . A nozzle for producing microdroplets of metal using electrodispersion, the nozzle comprising a reservoir for molten metal, a nozzle opening for directing the molten metal in a flow direction out of the reservoir and a channel connecting the reservoir with the nozzle opening, wherein the nozzle further comprises a first electrode such as a metal piece and a device to apply an electric field between the first electrode and the molten metal with a force per unit area generated by the electric field at the molten metal being larger than a surface tension of the molten metal. 
     
     
         25 . The nozzle according to  claim 24 , wherein the first electrode comprises an essentially cuboid shape. 
     
     
         26 . The nozzle according to  claim 24 , wherein the electric field generated between the first electrode and the molten metal has a field strength which lies in the range of 1 V/cm to 1000 V/cm. 
     
     
         27 . The nozzle according to  claim 24 , wherein the electric field is generated by one of an alternating current and a direct current. 
     
     
         28 . The nozzle according to  claim 20 , wherein a cross-section of the channel in the flow direction of the molten metal comprises one of a square shape, a rectangular shape, a round shape, an oval shape, a polygonal shape and a triangular shape. 
     
     
         29 . The nozzle according to  claim 20 , wherein the cross-section of the channel in a plane perpendicular to the flow direction of the molten metal comprises a circular, rectangular, triangular, oval, or polygonal shape. 
     
     
         30 . The nozzle according to  claim 20 , wherein the channel comprises a length in the range of 0.1 to 100 mm, 
     
     
         31 . The nozzle according to  claim 20 , wherein the nozzle opening comprises a circular, oval, square, rectangular, triangular, polygonal or any other shaped cross-section. 
     
     
         32 . The nozzle according to  claim 31 , wherein a rectangular nozzle opening comprises a length in the range of 0.5 to 10 cm; or wherein a circular nozzle opening comprises a diameter of 10 to 500 μm, preferably 20 to 200 μm, in particular 30 to 100 μm. 
     
     
         33 . The nozzle according to  claim 20 , wherein the reservoir comprises an inner shape, which is connected with the channel via a channel opening in the inner shape, wherein the inner shape of the reservoir is rounded or sloped at the channel opening such that the molten metal is guided to the nozzle opening. 
     
     
         34 . The nozzle according to  claim 20 , wherein the formed microdroplets comprise a size in the range of 0.010 to 500 mm. 
     
     
         35 . A combination of a melt spinner for forming elongate metal fibers with a nozzle according to  claim 20 , wherein the melt spinner further comprises a rotatable wheel with a circumferential surface, at least one rotating planar surface and collection means for collecting solidified fibers formed on one of the circumferential surface and the rotating planar surface of the rotatable wheel from the molten metal and separated from the rotatable wheel by forces generated by the rotation of the rotatable wheel. 
     
     
         36 . A method of forming microdroplets using at least one of an external force field, a gas flow and electrodispersion, wherein the method comprises the following steps:
 providing a flow of molten metal at a nozzle opening; and   applying a force per unit area at said nozzle opening by means of one of the on said flow of molten metal, with said force per unit area being larger than a surface tension of said flow of molten metal.   
     
     
         37 . The nozzle according to  claim 19 , wherein the cross-section of the channel in a plane perpendicular to the flow direction of the molten metal comprises a circular, rectangular, triangular, oval, or polygonal shape. 
     
     
         38 . The nozzle according to  claim 19 , wherein the nozzle opening comprises a circular, oval, square, rectangular, triangular, polygonal or any other shaped cross-section.