Apparatus and method for preparing spherical metal powder based on one-by-one atomization method for uniform droplets

Patent metadata

Field	Value
Publication number	US-11344950-B2
Application number	US-201917280168-A
Country	US
Kind code	B2
Filing date	Sep 25, 2019
Priority date	Sep 25, 2018
Publication date	May 31, 2022
Grant date	May 31, 2022

Abstract

An apparatus includes a housing, a crucible disposed in the housing, and a collection bin. A turnplate disposed in a powder collection area is of an inlaid structure. A concentric circular groove is provided on the atomization plane. An air hole is provided in the turnplate. The present invention combines the pulsated orifice ejection method and the centrifugal atomization method, in cooperation with the turnplate structure and subjecting the turnplate surface to induction heating, so that a metal liquid is allowed to break through the split mode of traditional molten metal, achieves a fibrous split mode that can be implemented only when an atomizing medium is an aqueous or organic solution, and prepares a high-melting-point metal powder that meets requirements, and has a controllable particle size, high sphericity, no satellite droplets, and good flowability and spreadability, and is suitable for industrial production.

First claim

The invention claimed is:

1. An apparatus for preparing spherical metal powder, comprising a housing ( 19 ), a crucible ( 5 ) disposed in the housing ( 19 ), and a collection bin ( 13 ) disposed under the housing,
wherein:
the crucible ( 5 ) is disposed at an upper portion of the housing ( 19 ), and the collection bin ( 13 ) is disposed under the crucible ( 5 );
a transmission rod ( 3 ) connected to a piezoelectric ceramic ( 1 ) disposed outside the housing ( 19 ) is disposed in the crucible ( 5 );
a position where the transmission rod ( 3 ) is connected to a top portion of the crucible ( 5 ) is sealed by a dynamic sealing ring ( 2 );
a lower end of the transmission rod ( 3 ) faces towards a center hole at a bottom portion of the crucible ( 5 ), and a perforated plate ( 20 ) having a plurality of holes is disposed at a bottom portion of the center hole; a resistive heater ( 6 ) is disposed about an outer wall of the crucible ( 5 );
a crucible air inlet ( 27 ) extending into the crucible ( 5 ) and a crucible exhaust valve ( 26 ) are disposed at a top portion of the housing ( 19 );
a diffusion pump ( 23 ) and a mechanical pump ( 22 ) are disposed on a side wall of the housing ( 19 );
a cavity air inlet ( 21 ) and a cavity exhaust valve ( 24 ) are disposed on the housing ( 19 ); and a furnace door ( 8 ) is installed on the housing ( 19 ); and
the collection bin ( 13 ) is fixedly connected with the housing ( 19 ) through a support ( 9 );
a through ring-shaped pipe ( 10 ) is disposed between the housing ( 19 ) and the collection bin ( 13 );
a turnplate ( 11 ) is disposed in the collection bin ( 13 ) and below the through ring-shaped pipe ( 10 ); the turnplate ( 11 ) is connected to a motor ( 16 ); a collection tray ( 15 ) is disposed at a bottom of the collection bin ( 13 );
a collection bin door ( 14 ) is installed on a side of the collection bin ( 13 );
wherein the turnplate ( 11 ) comprises:
a T-shaped base having a receiving portion ( 28 ) connected with a support portion ( 29 ); an upper surface of the receiving portion ( 28 ) is provided with a circular groove with a certain radius which is coaxial with the center of the receiving portion; wherein the base is made of a material with a thermal conductivity of less than 20 W/m/k;
an atomization plane ( 30 ) with a disc structure, matching in interference fitting with the circular groove in the receiving portion; wherein the atomization plane ( 30 ) is made of a material having a wetting angle of less than 90° to an atomized droplet ( 18 ); a center of the turnplate of the atomization plane is provided with a concentric circular groove ( 32 ) disposed below the perforated plate ( 20 );
during operation, molten droplets ( 18 ) drop from the crucible through the ring-shaped pipe ( 10 ) onto the concentric circular groove ( 32 ) in the center of the rotating turnplate ( 11 ), spread across the atomization plane under a centrifugal force generated by the rotation of the turnplate, and drop into the collection tray; and
an induction heating coil ( 17 ) is disposed outside the turnplate ( 11 ), configured to heat an upper surface of the turnplate ( 11 ),
wherein the piezoelectric ceramic ( 1 ), the transmission rod ( 3 ), the crucible ( 5 ), the perforated plate ( 20 ), the ring-shaped pipe ( 10 ), the turnplate ( 11 ), the concentric circular groove ( 32 ), and the induction heating coil ( 17 ) are located on a same axis extending from top to bottom of the apparatus, and
wherein, during operation, a material is melted in the crucible, the induction heating coil heats an upper surface of the turnplate to a temperature higher than a melting point of the metal material, molten droplets drop from the crucible through the ring-shaped pipe ( 10 ) onto the concentric circular groove ( 32 ) in the center of the rotating turnplate ( 11 ), spread across the atomization plane under a centrifugal force generated by the rotation of the turnplate, and drop into the collection tray.

2. The apparatus according to claim 1 , wherein a diameter of the center hole of the crucible ( 5 ) is greater than that of the small hole of the perforated plate ( 20 ), and the plurality of holes in the perforated plate have diameters ranging from 0.02 mm to 2.0 mm.

3. The apparatus according to claim 1 , wherein a wetting angle between a material of the perforated plate ( 20 ) and a molten material ( 4 ) in the crucible ( 5 ) is greater than 90° .

4. The apparatus according to claim 1 , wherein a rotational speed of the turnplate ( 11 ) is 10000 rpm to 40000 rpm.

5. The apparatus according to claim 1 , wherein a heating thickness of the induction heating coil ( 17 ) ranges from 5 mm to 20 mm, the induction heating coil ( 17 ) is connected with a converter and a regulated power supply that are disposed outside the housing ( 19 ).

6. A method for preparing spherical metal powder using the apparatus according to claim 1 , comprising the following steps:
S1. charging: grinding a raw material to a preset average particle size and then charging the raw material into the crucible ( 5 ) for sealing;
S2. vacuumizing and heating: vacuumizing the crucible ( 5 ) and the housing ( 19 ) by using the mechanical pump ( 22 ) and the diffusion pump ( 23 ), and filling the crucible ( 5 ) and the housing ( 19 ) with a high-purity inert gas; setting a heating power of a resistive heater ( 6 ) based on a melting point of the raw material to-be-heated, and after a heating temperature reaches the melting point, keeping the temperature to melt the raw material into a melt ( 4 ) completely; manually adjusting a position of the transmission rod ( 3 ), until a preset distance exists between the transmission rod ( 3 ) and the perforated plate ( 20 );
S3 induction heating: with a rotational speed preset, enabling the turnplate ( 11 ) to rotate at a high speed by using the motor ( 16 ), followed by heating an upper surface of the turnplate ( 11 ) rotating at the high speed to a temperature higher than the melting-point of a metal material by using the induction heating coil ( 17 );
S4. preparing the powder: firstly, manually adjusting the position of the transmission rod ( 3 ) to the preset distance from the perforated plate ( 20 ); secondly, injecting a high-purity inert protective gas into the crucible ( 5 ) by using the crucible air inlet ( 27 ) disposed on the housing ( 19 ) and extending into the crucible ( 5 ), to form a positive pressure difference between the inside and the outside of the crucible ( 5 ), thereby driving the melt ( 4 ) to fill the center hole at the bottom of the crucible ( 5 ); and finally, inputting a pulse signal with a wave pattern to the piezoelectric ceramic ( 1 ), wherein the piezoelectric ceramic ( 1 ) produces a downward displacement that is transferred by the transmission rod ( 3 ) connected to the piezoelectric ceramic ( 1 ) to the molten metal in the vicinity of the center hole, so that the molten metal is ejected from the perforated plate ( 20 ) at the bottom of the center hole to form uniform droplets ( 18 );
S5. forming the powder: the uniform droplets ( 18 ) dropping freely on the turnplate ( 11 ) rotating at a high speed through the ring-shaped pipe ( 10 ); the molten uniform droplets ( 18 ) first dropping in the concentric circular groove ( 32 ) in the center of the turnplate ( 11 ), and gradually spreading over the groove; because centrifugal force is small at this time, the droplets will not disperse immediately, but spread in a circle on the turnplate ( 11 ); when the droplets spread in a certain range and the centrifugal force is large enough, spread metal will disperse on the turnplate ( 11 ) in a fiber line shape to an edge of the turnplate ( 11 ) under the action of centrifugal force, and finally split into tiny droplets to fly out; the tiny droplets solidi

Assignees

• Wang Xiaoming
• Zhao Yang
• Chang Qing
• Ren Zhiqiang
• Zhu Sheng
• Wang Wenyu
• Shi Jing
• Han Guofeng
• Teng tao
• Wang Dongyang
• Peng Zhanwu
• Qin Zhiyong
• Univ Dalian Tech
• Dalian Universtty Of Tech

Inventors

• Wang Xiaoming
• Zhao Yang
• Chang Qing
• Dong Wei
• Xu Fumin
• Ren Zhiqiang
• Zhu Sheng
• Wang Wenyu
• Shi Jing
• Han Guofeng
• Teng tao
• Meng Yao
• Bai Zhaofeng
• Wang Yanyang
• Han Yang
• Li Guobin
• Wang Dongyang
• Peng Zhanwu
• Qin Zhiyong

Classifications

• B22F1/065

  Spherical particles · CPC title

• B33Y70/00 Primary

  Materials specially adapted for additive manufacturing · CPC title

• B22F2301/10

  Copper · CPC title

• B22F9/10 Primary

  using centrifugal force · CPC title

• B22F2201/11

  Argon · CPC title