Apparatus for electric-erosion dispersing of metals

FIELD: powder metallurgy, namely apparatuses for producing powders of electrically conducting materials.

SUBSTANCE: apparatus includes dielectric vessel with opening in lower portion for supplying working liquid in it, additional bottom of dielectric material made of mutually parallel rods or prisms, plate-type electrodes connected with electric pulse generator. In order to decrease breakdown voltage of inter-electrode gap apparatus includes three plate electrodes connected in parallel with electric pulse generator and movable dielectric blinds covering electrodes for controlling electric current density. Mean electrode serves as cathode; boundary electrodes serve as consumable anodes.

EFFECT: enhanced efficiency, lowered specific energy consumption, improved stability of process.

3 dwg, 1 tbl, 1 ex

 

The invention relates to powder metallurgy, in particular to a device for the production of fine powders of electrically conductive materials, and can be used to produce metal powders of oxides, carbides, nitrides, catalysts, chemical processes, pastes and slurries.

The known device for electrical discharge dispersion of metals electrical discharges in dielectric liquids, intended for the production of fine powders of metals and other electrically conductive materials.

A device for electrical discharge dispersion (AED) metals spark discharges between the two plate electrodes are installed in the reactor, through which the bottom-up pumped working fluid that is designed to produce fine powders of metals and other electrically conductive materials. The device has additional mesh plate, made of a dielectric material, in which Neverlin holes with a diameter of 1-2 mm, the Electrodes are lowered into the vessel by a dielectric guide at an angle 70-85° and pressed against the mesh plate spring plungers, through which the electrodes are connected to the output terminals of the generator of electrical impulses. Between the electrodes on the mesh bottom fall asleep pieces dispersible what about the metal. When applying to the electrodes an electric pulse between the pieces of metal with sparks in the working fluid, leading to erosion of the metal. The products of erosion in the form of fine metal powder are carried by the flow of the working fluid in cumulative capacity [1].

A disadvantage of this device is the wide distribution curve particle size, as the distance between the lower ends of the electrodes is less than that between the upper and the electrical resistance of the lower layer dispersible metal is much less than the top layer, which creates unequal conditions for the dispersion in height of the layer of metal pieces. The device has a low productivity, high specific energy and instability as a result of constant clogging of the mesh of the bottom of the small pieces of the worked metal and metal powder.

Closest to the claimed known technical solution (prototype) is a device for AED metals consisting of a dielectric vessel (reactor) and two plate electrodes connected to a generator of electric pulses. The reactor has an additional dielectric plate, composed of parallel rods or prisms tapering part up, slot gap between the have them, directed from one electrode to the other. The inclined surface of the rods and prisms form tapering to a slit gaps grooves that roll pieces dispersible metal, forming a conductive chains between the electrodes to which the shortest path skips spark discharges, causing erosion of the metal. The products of erosion in the form of fine powder are carried by the flow of the working fluid in cumulative capacity [2].

A disadvantage of this device is the limited possibilities of controlling the degree of dispersion of the obtained powder selected by the reactor power from the generator of electrical impulses, and consequently, performance in the dispersion of materials with different conductivity or even with different geometric dimensions of the pieces of metal.

The invention solved the problem of the expansion of technological capabilities of the dispersion process, improve productivity, reduce energy consumption, improve the stability of the process.

This is achieved by a device for electrical discharge dispersion of electrically conductive material containing a dielectric vessel with a hole in the bottom to feed him working fluid, an additional plate made of a dielectric material in the form of steam is lennyg rods or prisms, plate electrodes connected to a generator of electric pulses, according to the invention to reduce the breakdown voltage of the interelectrode gap are three plate electrode, closing movable dielectric shutters to regulate the current density, and the middle electrode is a cathode, and consumed at the anode and is connected to the pulse generator in parallel.

The proposed device comprises a vessel 1, made of a dielectric material (reactor) (figure 1), which sets out three plate electrode made of the same material and subjected to dispersion. The middle electrode is the cathode 2 and the side mounted around the walls of the reactor are the anodes 3 and connected to the pulse generator in parallel. The cathode is closed on both sides of the movable dielectric shutters 4, with a small sliding friction in the guide grooves milled in the wall of the reactor, and the anodes are closed shutters facing the cathode. Blinds are a plate thickness of 3-6 mm, made of dielectric material, having a porous structure (vinyl plastic, polyamide, polystyrene) (figure 2). The mesh bottom is made from the same dielectric material. Monolithic structure barndoors bottoms necessary to prevent the formation of conductive areas on the shutters and the bottom in the clogging of pores in such materials as fiberglass, what causes short circuits in the reactor and the failure of both the reactor and the pulse generator. In the upper part of the blind drilled a number of holes 5 to prevent overflow of the working fluid through the top edge of the reactor in the electrode chambers. On the side edge of the curtain marked scale 6 to set the value of the current density. The mesh bottom is made of a thick plate, which is cut trench 7 depth to the middle of the thickness of the bottom and a width larger than the pieces of dispersible material in the direction from electrode to electrode. At the bottom of the gutters propylene through the slit 8 of a width of 0.5-1.0 mm, the working fluid is pumped from the storage tank through the opening 9 of the reactor and makes the products of erosion in the form of fine powder in cumulative capacity through hole 10.

Installation of the cathode in the middle of the reactor allows twice to lower the breakdown voltage for the layer dispersible material, is poured between the electrodes, which enables dispersing clubalektrablue or covered with a thick oxide film materials, keeping the power selected by the reactor from a generator of electric pulses, and therefore, to maintain productivity dispersion. The overlapping part of the surface of the movable dielectric shutters allows the reg is on the current density through the layer of dispersible material and thus to modify the dispersion and the range of dispersion of dispersion of the material obtained.

Thus, the proposed device allows you to narrow the distribution of dispersion, to obtain a high productivity, reduce energy consumption during the production of fine powders.

Example 1.

The proposed device is shown in figure 1, has the following parameters: the width of the electrodes 300 mm, the distance between the electrodes 300 mm, the height of the fluid level from the slotted plate 500 mm Electrodes connected to the pulse generator with a capacity of 50 kVA. Dielectric barndoor set sequentially to a height of 100, 200 and 300 mm above the slotted plate. In the reactor fall asleep granules titanium size 5-12 mm in height from the level of the gap of the bottom 300 mm of Conduct dispersion granules of titanium in air for 2 hours at each position of the shutters. The results of the experiment are given in table. 1. For comparison, the results obtained for the known device (prototype). Granulometric composition of the obtained powder is shown in figure 3 the curves 1, 2, 3, and 4, respectively, the number of the experiment. In the known device (prototype) mode options are not regulated.

Literature

1. Inventor's certificate SU 663515, 23 P 1/02. Fominsk, L.P. the Device for electrical discharge dispersion of metals.

2. Russian Federation patent RU 2002589 C1, 5 22 F 9/14. V.I. Tarasov, Kozarek I., Fominsk, L.P. the Device for electroerosion dispersion of metals.

Device for electrical discharge dispersion of electrically conductive material containing a dielectric vessel with a hole in the bottom to feed him working fluid, an additional plate of a dielectric material made of parallel rods or prisms, plate electrodes connected to a generator of electric pulses, characterized in that for reducing the breakdown voltage of the interelectrode gap it contains three plate electrode connected to the pulse generator in parallel, and provided with a movable dielectric shutters covering the electrodes to control the current density, and the middle electrode is a cathode, and at - consumable anodes.



 

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