SU1121101A1 - Device for obtaining powder - Google Patents

Description

. t The invention relates to the field of metal powder production by electric arc spraying of a melt. The closest in technical essence and the achieved result to this is a device for producing metal powders by electric arc spraying a melt including a metallographic receiver with a hole for the melt, in the bottom of which an electrode is installed and a lower electrode installed under the hole, in which to increase the dispersion of the resulting powder on the bottom electrode , made in the shape of the hole of the metal receptacle, installed pipe of non-conductive refractory material and entering the hole for Poor with a Cl3 gap. The downside of the device lies in the trace factor. To increase the dispersion of the powder, it is necessary to reduce the length of the jet. However, with a certain jet length, a smaller breakdown gap, between the electrode No. 1 or between the lower electrode and the jet, a stable electric arc is ignited and the crushing efficiency decreases sharply. In addition, since the temperature of the electric arc reaches significant values (more), there is an intense heat erosion of the materials of the electrodes and devices that form the hollow jet. Thus, significant drawbacks are the low yield of fine powder fractions, intensive destruction of electrodes and devices forming a hollow jet. The purpose of the invention is to increase the dispersion of the resulting powder and increase the reliability of the device. This goal is achieved by the fact that a device for producing a powder by arc spraying of melts containing a metal capacity with a melt hole and an electrode installed under the hole, made in the shape of a metal intensity hole and connected to a non-conductive refractory pipe entering the hole in the bottom with a gap. a wire refractory electrode rod made of the same metal as the melt or alloying metal, and one co 12 its contact ruet with the liquid metal, and the other - with the source voltage. The drawing shows a diagram of the proposed device. The device includes a metal consumption 1 with a melt hole 2. Under the hole 2 is the electrode 3, made in the shape of the hole. A tube 4 of refractory non-electrically conductive material is inserted into the electrode 3, which enters the hole 2 with a gap. The electrode 3 is connected to a voltage source 7 by a current lead 8. The device operates as follows. The molten metal from the metal 1 flows through the annular hole 2 to the electrode 3 in the form of a hollow jet. After applying voltage from source 7 to electrodes 3 and 5, an electric current passes through the hollow jet and the rod-electrode 5. Since the current passing through a hollow metal jet and a rod-electrode has the same magnitude, but the opposite direction, repulsive electrodynamic forces arise between them due to the interaction of their magnetic fields, which break the jet, and pulsed electric arcs in its ruptures. The same electrodynamic forces emit ionized particles and droplets from the interelectrode gap and thereby extinguish the arc. The pause of the current lasts until the newly formed jet from the floor, the pad, closes the electrical circuit again. Then the cycle repeats. The dispersion of the powder obtained is increased due to the additional electrodynamic interaction of the currents flowing through the hollow jet and the rod-electrode, and the reliability of the device increases due to the ejection of the arc and: from the interelectrode gap. Example. A hollow stream of tin with a length of mm, an inner diameter (outer diameter of the pipe) of 8.2 mm, an outer diameter of 9.2 mm (diameter of the metal capacity). When a voltage of 150 V was applied to it, it was crushed into particles of the next particle size 11211014

composition (results are averaged over 3 experiments).

The results of the experiments are given in

the table.

As follows from the example, when using the proposed device, the output of the fine fraction of the powder (-0.16 mm) increases more than 5 times, and when the jet length decreases from 20 to 14 mm with the same voltage, 10 times. In this case, during the three experiments, no noticeable erosion of the materials of the device was observed. The known device at a voltage of 150 V and a jet length of 14 mm is destroyed during the first experiment, since in this case the electric arc is stable, in which the refractory materials melt.

forming the jet and used for the manufacture of electrodes (corundum, zirconium di boride, etc.).

Thus, the proposed device differs from the known one, and its application gives a new technical and economic effect — an increase in the yield of fine powder fractions and an increase in the service life. The device is expediently used for the production of powders from reactive metals and alloys, for example, tin, zinc, aluminum alloys and rare earth metals with cobalt.