SU1002096A1 - Apparatus for producing metallic powders from melts - Google Patents

Description

The invention relates to the field of powder metallurgy, in particular, to devices for producing metal powders by spraying melts.

A device for producing metal powders is known, consisting of a pouring nozzle mounted in the housing of a rotating bowl, an annular nozzle mounted in the upper part of the spray chamber, and a deflector located above the bowl Cl.

The disadvantages of this device are the considerable oxidation of the powder obtained, due to the collision of melt particles with a stream of water coming from the annular packing.

The closest to the invention in technical essence and the achieved result is a device for obtaining metal powders from melts, including a metal receiver, a ring nozzle, a heated crushing device with a concave working surface and a replaceable central one.

The disadvantages of this device include the low intensity of the melt dispersion process and the low yield of the fine fraction of the powder.

The aim of the invention is to intensify the process of dispersing the melt and increasing the yield of the fine fraction of the powder.

To achieve the goal, a device for producing metal powders from melts, including a metal receiver, an annular nozzle, a heated crushing device with a concave surface and a replaceable central liner, the crushing device is made with curvilinear channels

15 of its working surface, wherein the area of the channels is half the area of the working surface.

FIG. 1 schematically shows an embodiment of the proposed device; in fig. 2 - a splitting device, top view; in fig-. 3 is a section A-A in FIG. 2

A device for producing metallurgical powders consists of a heated metal reservoir 1 of a heated crushing device.2 with an interchangeable central aperture 3 and curvilinear channels 4 made on the concave working surface of the device 2, an annular nozzle 5 (Laval nozzles with blades for twisting sparks gas) and a removable ring screen 6. The device for producing powder works as follows. During free flow from the metal receiver 1, the melt jet falls on the central liner 3 of the crushing device 2, where under the action of its own kinetic energy it is divided into separate strands formed by curvilinear channels 4. When moving along the channels, the melt twists in the direction opposite to the direction of rotation of the supersonic gas flow coming from the nozzle 5. The final dispersion of the particles occurs when the individual melt strands collide with the flow of the spraying gas, after which the dispersion During the collision with the annular screen 6, the melted drops of the melt acquire a scaly shape and enter the powder receiving {receiver in FIG. J is not shown; To obtain spherical powder particles, the melt is sprayed with no screen 6. By changing the drop height and the melt stream diameter, the speed and flow rate of the dispersing gaea energy carrier, as well as the diameter of the ring screen, it is possible to produce metal powders of any size from 1-10 microns to 2-3 mm of the most various form. - from pr.vilnaya spherical to fragmentation and scaly. As a gas-energy carrier can be used any gas or mixture of gases. Example. The crushing device was made of siliconized graphite, the bowl diameter was 60 mm, and the radius of curvature of the working surface was 75 mm. To obtain a uniform distribution of the jets Γ, the number of channels was chosen equal to 12. The geometric axes of the channels were spaced 15 ° apart. Channel marking was performed as follows. The circumference of the working surface was divided into 12 points 15 from each other, then a line connecting the geometric center of the crushing device with one of the points on its surface was sequentially from each point with a radius equal to half the working diameter of the crushing device. circle. The resulting curve was the axis of the channels. The width of the channels was determined by the diameter of the working surface of the crushing device; the total area occupied by the channels should be equal to half the total area of the working surface of the crushing device. The depth of the channels is 2-3 mm, which is due to the best conditions for the formation of the jet; at a depth of less than 2 mm, the flow is disrupted and no uniform melt jets are formed. If the depth of the channels exceeds 3-4 mm, metal freezing on the bottom of the channel is detected, and this process continues until the depth decreases to 2-3 mm. This phenomenon is due to the fact that this second melt flow rate corresponds to a well-defined channel cross section; for this particular case, it corresponds to a depth of 2-3 mm. The metal receiver is lined with a refractory gasket; a refractory bushing with a calibrated orifice with a diameter of 6 mm is inserted into its bottom. Air was used as a dispersing gas in comparative tests. The pressure was maintained constant and equal to 500 N / m. The Laval annular nozzle provided a flow velocity of 520 m / s. Vanadium cast iron was used as the sprayed alloy. The ring screen was not installed. During the tests, the following results were obtained Lsm. table).

Known device

8.6. 10.2 31.5 28.7 11.4 8.1 (prototype)

Proposed

1.4 b; 1 10.3 26.3 .29.7 device The obtained results indicate that the proposed device is 5

0.3 1.2

8.9 17.3 compared with the device prototype provides an increase in the output of tails

Claims (1)

Claim A device for producing metal powders from melts, including a metal receiver, an annular nozzle, a heated grinding device with a concave working surface 15 and a removable central liner, characterized in that, in order to intensify the process of dispersing the melt and increase the yield of fine powder fraction, the grinding device is made with curved channels on its working surface, while the area of the channels is half the area of the working surface.