SU1405976A1 - Apparatus for quick cooling of metallic particles - Google Patents

Abstract

The invention relates to the field of metallurgy, namely to the production of rapidly precipitated particles of metal alloys. The aim of the invention is to increase the strength properties of alloys due to an increase in the cooling rate during crystallization of metal particles. A melt is fed to the centrifugal disk evacuated and filled with coolant. Under the cooling element inside the disk there is a porous layer that absorbs the coolant, which spreads over the entire surface of the cooling element. When the cooling element is heated and the heat carrier evaporates, the porous layer ensures its closed circulation. 3 hp ff, 1 ill. from 9 (L

Description

ate

with m

Od

The invention relates to metallurgy, ifHH, namely, to the production of fast-h a j a meHHbix particles of metal alloys.

The aim of the invention is to improve the strength properties of alloys as a result of an increase in the cooling rate during crystallization of metal particles.

The drawing shows devices for rapid cooling of metal particles, a general view.

The device comprises a cooling element 1, a housing 2, a cover 3, a sleeve 4, which are connected tightly. The device is mounted on the drive shaft 5. Symmetrically, a balanced vacuum valve 6 and a pressure valve 7 are located in the housing 2. A layer of porous material 8 is located on the inner surface of the cooling element. On the outer side of the cover 3 there are radiators 9.

A device for the rapid cooling of metal particles works as follows.

Through the valve 6, the cavity of the device is vacuumed and the required amount of heat carrier 10 is injected. Through the shaft 5, the device is rotated at the speed required for operation. When the device rotates under the action of centrifugal

forces the heat carrier 10 moves along the inclined wall of the housing 2 and reaches the inner surface of the cooling element 1 and soaks the layer .Q

porous material 8. Under the action of capillary forces, the coolant 10 spreads over the entire surface of the cooling element 1. When molten metal hits the cooling. element 1 causes a considerable overheating of the latter and the temperature of its inner surface becomes greater than the boiling point of the coolant 10. The coolant 10 evaporates and takes heat from the working surface of the cooling element 1. Under the action of centrifugal force, a new

35

50

party heat carrier. The coolant vapor condenses when it comes into contact with the lid 3, the temperature of which is lower than the condensation temperature of the coolant. It is warm, vyde

5 0 5

about

Q

five

0

The condensation of the coolant vapor, which was condensed, is removed by the lid 3, and the formed coolant under the influence of centrifugal force returns to the cooling element 1.

The device is intended for operation of fast-cooled-particle production plants in which a concave cooling element with a taper angle from 0 (flat disk) to 180 (inner surface of the cylinder) is used. In this case, to ensure the rise of the coolant and in accordance with the shape of the cooling element, the taper angle of the inner wall of the casing is 10-172 °, since then the accumulation zone of the coolant near the cooling element has a minimum volume and provides free removal of the coolant vapors from the evaporation zone.

The temperature on the working surface of the cooling element is maintained at the required level and is determined by the boiling point of the heat transfer fluid, which in turn depends on the composition of the latter and on the pressure in the cavity of the device. The pressure is regulated by the amount of coolant and the intensity of the heat sink from the cover.

The choice of heat transfer medium according to its boiling point and heat transfer capacity depends on the required temperature of the working surface of the cooling element, its thickness and thermal conductivity.

Secondary cooling through Krishka can be accomplished by transferring cold water, a pelvis, or other consumable coolant to it, which washes the radiators that increase the intensity of the heat sink.

As heat carriers for various operating modes of the device, the following can be applied: water for a temperature range of 80 — acetone 40–70 ° C; dichlorofluoromethane O - 20 C, trichlorofluoromethane 10 - 4i) C, dichlorodifluoromethane (-40) - (- 20GS.

The cooling rates for images with a thickness of 20–40 µm, depending on the angle of inclination of the cooling surface / DX1Y of the proposed device and the prototype, are given in the table.

The device can be applied to various methods for producing rapidly cooled particles. The maximum cooling rate is achieved in the case of a taper of the cooling element 0 ° (inner surface of the cylinder). However, this causes difficulties with the supply of the melt to the cooling surface and removal of solid metal from it, which leads to a decrease in the performance of the device. High performance is provided in the case of taper angles ensuring the discharge of metal from the cooling surface, but at the same time the cooling rate of the metal is reduced.

In the preparation of rapidly cooled particles from different alloys, the optimal combination of productivity and cooling rate and, consequently, the angle of inclination of the cooling surface is chosen. In the device, it is important the ratio of the angles of taper of the cooling surface (l) and the body

,, o - 10

(d): / Q Q) providing

, Q y Ch- posischss

unimpeded supply of coolant to the cooling surface.

The values of the angle at the top of the cooling element and the corresponding values of the angles of inclination of the wall of the housing and the average values of the increase in the mechanical properties of the samples obtained from their rapidly cooled particles are given.

 B%

OSH15-18

90 170

19-21

22-25

During operation of the device, the melt is supplied in the form of a thin jet with a diameter of 1-2 mm from the dispensing tank, in which an inert gas overpressure of 0.3-0.5 atm is created. at an angle of 90 to the cooling surface. The linear velocity of the cooling surface at the point of contact with its melt stream is 20–40 m / s, which is achieved at a frequency of rotation of the cooling element of 3000–5000 rpm. Height of the cooling element 200 mm; diameter is 300 mm.

The device, in comparison with the prototype, allows to increase the strength properties of alloys by 15-25%. This is achieved by maintaining the temperature of the cooling element at a level of 20-25 ° C by evaporating the intermediate heat carrier with a low boiling point. At the same time, the cooling rate of particles with a thickness of 20 µm increases from 10 to 5 10 K / s.

The simplicity of the device can significantly reduce the cost of its manufacture and operation.

Claims (4)

1. A device for rapid cooling of metal particles, comprising a housing, a conical cooling element and a lid, hermetically connected and mounted on a rotary shaft, characterized in that, to increase the strength properties of the alloys due to an increase in the cooling rate during crystallization of the metal particles, the inner surface of the housing is filled taper with a taper angle with "equal to 10 - 172 °, the taper of the cooling element / J is determined by the formula d -10  about: 9 2. A device according to claim 1, characterized in that the cap is made of a material more thermally conductive than the housing and the inner sleeve. 3. A device according to claim 2, characterized in that the lid on the outside has cooling radiators. 4. The device according to claim 2, about the fact that the inner surface of the cooling element is made of porous material.