SU1204325A1 - Apparatus for producing metal powders by melt-spraying - Google Patents

Description

The invention relates to powder metallurgy, in particular to the preparation of metal powders by spraying a melt with a stream of energy carrier.

The aim of the invention is to improve the quality of the powder and expand the technological capabilities of the device.

Figure 1 shows the scheme of the working nozzle, longitudinal: section; figure 2 is the same cross section; Fig. 3 is a diagram of spraying and fiber forming chambers, cross section.

The device for producing powders contains an axisymmetric nozzle 1 for supplying the melt, a cavity 2 for supplying the carrier; a working nozzle 3 for accelerating the energy carrier, made in the form of a conical body (not marked) equipped with radially arranged 4 Laval nozzles; a fiber-forming chamber 6, an ejector 7, and a coolant supply device 8. The cavity 2 for supplying the energy carrier is made tapering towards the entrance to the working nozzle 3. Spray chambers 5 and 6 forming the working area of the device with a flow-through part (not indicated), which is a truncated cone with a smaller base facing the working nozzle 3. The ejector 7 is supplied with corrugated water. cooled surface and installed in the fiber-forming chamber 6, with a larger base of the truncated cone made passing into a corrugated cooling surface.

The device works as follows.

Under high pressure, the energy carrier (compressed air, steam or inert gas) is supplied through the cavity 2 to the working nozzle 3. The leakage through the flowing part of the working nozzle 3, the energy carrier is accelerated and enters the metal jet spray chamber 5 at a higher speed. Since the beginning of the spraying chamber 5 coincides with the outlet section of the nozzle 1 (they are located on the same axis), a vacuum is created at the entrance of the nozzle 1 and the molten metal is sucked into the device under the action of the ejection force. In the spray chamber, a disturbed flow of energy carrier acts on the metal stream and destroys the stream into individual droplets. Under the action of aerodynamic forces, metal droplets enter the fiber-forming chamber 6, in which more heavy drops interact with a cooled corrugated surface and are pulled out of the latter thin fibers. Drops of metal that have avoided contact with a corrugated surface, when cooled, become a powder with a spherical surface.

The presence in the device of a working nozzle 3 in the form of a closed system of discrete axisymmetric nozzles 4 allows to obtain a supersonic flow of energy carrier with a high degree of turbulence, which leads to

In this case, the influence of a stable flow of energy carrier on a stream of molten metal is applied. The number of gas jets that make up the disturbed flow of energy in the chambers

5 5 and 6 (spraying and fiber formation), as well as the geometry of the flow path of the nozzles 4 forming these jets, are selected taking into account the maximum effect, the energy carrier on the molten metal stream.

The presence of a device 8 for supplying a cooling medium and an ejector 7 makes it possible to obtain stable intensive cooling of the corrugated

5, the presence of the ejector 7 allows increasing the ejection capacity of the device by an amount sufficient to compensate for losses caused by friction of the energy carrier flux on the corrugated surface, and also improve the uniformity of distribution of the blowing products in the energy carrier flux at the exit of the device. The absence of zones of contact with the molten metal in the device prior to filing it with fiber-forming chamber 6 does not increase productivity, and dividing the working zone into the spray chamber 5 and the fiber-forming chamber 6 coupled to it creates metallic fibers during operation of this device. expiration

5 energy carriers, metal powder with a high percentage of the planned fraction in the finished product. In addition,

0

five

stability in operation with relative simplicity of design.

The table shows the comparative data of the proposed and known devices.

Thus, the use of the proposed device allows improving the quality of the obtained powder (narrowing its size range from 130-800 to 42-260 microns). At the same time, the technological capabilities of the device expand (not only powders are obtained, but also metal fibers of a narrow size range).

Indicators

:: t

Offered- Known I something

Pr he is singleness, kg / h

The diameter range of spherical powders, microns

600

427

42 - 260 130 - 800

Metal fiber length

mm

Diameter of metal fibers, micron

5-16

4-25

iactmS

S

eight

VNIIPI Order 8460/10 Circulation 746 Subscription Branch PPP Patent, g.Uzhgo.rod, st. Project, 4

Claims (1)

DEVICE FOR PRODUCING METAL POWDERS BY MELT SPRAYING, comprising an axisymmetric nozzle for supplying a melt, a cavity for supplying energy, a working nozzle for accelerating the energy carrier, a powder formation chamber with a working zone _f ejector and a device for supplying a cooling medium, characterized in that powder quality and expanding the technological capabilities of the device, the working nozzle is made in the form of a conical body equipped with radially located Laval nozzles, a cavity for the energy carrier door is made tapering towards the entrance to the working nozzle, and the working zone is made in the form of spray and fiberization chambers with a flowing part, which is a truncated cone facing a smaller base to the working nozzle, while the ejector is equipped with a corrugated cooled surface and is installed in the fiberization chamber, and the larger base of the truncated cone is made turning into a corrugated cooled surface. > 1 1204325