RU2795311C1 - METHOD FOR PRODUCING A LEAD-ANTIMONY ALLOY FROM POWDERS OBTAINED BY ELECTROEROSIVE DISPERSION OF PbSb-3 ALLOY WASTE IN WATER - Google Patents

Abstract

FIELD: powder metallurgy.

SUBSTANCE: invention is related in particular to production of alloys by spark plasma alloying. It can be used in production of lead alloys for gratings of lead batteries. The lead-antimony alloy is obtained by spark plasma fusion of powders obtained by electroerosive dispersion of PbSb-3 alloy waste in distilled water at a temperature of 300°C, pressure of 40 MPa and exposure time of 5 min.

EFFECT: fine-grained structure of the alloy with a uniform distribution of phases and low porosity.

1 cl, 5 dwg, 3 ex

Description

The invention relates to non-ferrous metallurgy and can be used in the production of lead alloys for gratings of lead batteries.

A known method for producing lead alloys for gratings of lead batteries [RU 2224040 C2 (C22C 11/08 (2000.01)]. The feedstock for the production of lead alloy is black lead, scrap lead and lead alloys, primary tin or tin-containing scrap, antimony or lead-antimony ligature, arsenic or arsenic ligature, as well as sulfur, copper and selenium.Black lead and scrap of lead and lead alloys are loaded into the boiler, if necessary, refined (the content of impurities is adjusted to the desired amount).After that, antimony or lead-antimony ligature is introduced into the lead in the required amount, mix the alloy until complete dissolution and analyze the resulting alloy.When the required concentration of antimony is reached, tin or tin-containing scrap is introduced into the alloy, the alloy is homogenized and arsenic or its alloy with lead, as well as copper and sulfur are introduced. tin in an alloy is produced according to the results of an express analysis and the chemical composition of charge materials by calculating and loading into the boiler the required amount for each of the materials. After melting, the alloy is stirred to average the chemical composition. The introduction of the above alloying components can be carried out simultaneously before the selenium loading operation. After obtaining an alloy of the desired composition in terms of alloying components, selenium is introduced into it, pouring it into the hopper of a vertical mixer. The stirrer is installed in the boiler, lowered into the melt, turned on, stirred for 10 minutes, and selenium is loaded into the formed funnel on the surface of the metal melt. After its loading, the mixing of the melt is carried out for 10 minutes, periodically changing the direction of rotation. Upon completion of the operation, the stirrer is removed from the boiler, the alloy is allowed to settle for 5 minutes, after which a sample is taken for express analysis. The temperature during the production of the alloy is maintained within 330...500°C.

This method has a number of disadvantages, namely a high number of operations, the need to constantly maintain the melting temperature in the boiler, which leads to increased energy consumption, low environmental friendliness of the process.

A known method for producing lead alloys for gratings of lead batteries, which is adopted as a prototype [Yap. application, cl. C 22 C 1/2, B 22 D 25/04, 56-47528, Appl. 27.9.79, 54-124409, publ. 30.4.81]. A lead alloy containing 2...3% antimony is melted at a temperature of 310°C, a lead wire containing sulfur, selenium or tellurium in the required amount is added, the autoclave is sealed, the temperature is quickly raised to 420-450°C and the pressure is up to 500 atm., at which the melt is held for 10 minutes.

However, this method cannot be applied to obtain the inventive lead alloy, as it requires complex equipment operating under high pressure. The disadvantage of the known method is the multi-operation process of obtaining an alloy, as well as high energy costs for obtaining melts.

A known method for producing a lead-antimony alloy [RU 2224040 C2(C22C 11/08 (2000.01)], the raw material for the production of which is black lead, scrap lead and lead alloys, primary tin or tin-containing scrap, antimony or lead-antimony ligature, arsenic or arsenic ligature, as well as sulfur, copper and selenium.

Black lead and scrap lead and lead alloys are loaded into the boiler, refined if necessary (the content of impurities is adjusted to the required amount). After that, antimony or lead-antimony ligature is introduced into lead in the required amount, the alloy is stirred until complete dissolution and the resulting alloy is analyzed. When the required concentration of antimony is reached, tin or tin-containing scrap is introduced into the alloy, the alloy is homogenized and arsenic or its alloy with lead, as well as copper and sulfur are introduced. Fine-tuning the content of arsenic and tin in the alloy is carried out according to the results of express analysis and the chemical composition of charge materials by calculating and loading the required amount for each of the materials into the boiler. After melting, the alloy is stirred to average the chemical composition.

The introduction of the above alloying components can be carried out simultaneously before the selenium loading operation.

After obtaining an alloy of the desired composition in terms of alloying components, selenium is introduced into it, pouring it into the hopper of a vertical mixer. The stirrer is installed in the boiler, lowered into the melt, turned on, stirred for 10 minutes, and selenium is loaded into the formed funnel on the surface of the metal melt. After its loading, the mixing of the melt is carried out for 10 minutes, periodically changing the direction of rotation. Upon completion of the operation, the stirrer is removed from the boiler, the alloy is allowed to settle for 5 minutes, after which a sample is taken for express analysis. The temperature during the production of the alloy is maintained within 330-500°C.

This method has a number of disadvantages, namely, the need for initial refining and the subsequent constant addition of alloying components, the multi-operation nature of the mixing process and constant monitoring of the chemical composition require time and energy costs.

The closest invention in terms of technical essence and the achieved result is a lead alloy for gratings of lead batteries [author's certificate SU 467524, IPC C22C 11/08, published on 15.04.1975], which contains antimony, arsenic, tin, selenium, in the following ratio of components , wt., %: antimony - 1.0…3.5; tin - 0.01…0.05; arsenic - 0.025 ... 0.2; selenium - 0.005…0.1; lead - the rest. The production of the alloy is carried out by casting molds.

The reasons preventing the achievement of the technical result indicated below, when obtaining a known lead alloy, include the low mechanical strength of the alloy, high brittleness, and the loss of casting properties.

The analysis of the analogue and prototype described above revealed that none of them achieves the desired result - obtaining a lead alloy of high corrosion resistance, mechanical strength and ductility.

The closest to the proposed method is the method of manufacturing a composite material based on copper, including mixing the initial powders of copper, metal oxides and graphite in a given ratio, molding from the prepared mixture of contacts by pressing under pressure, followed by sintering in a protective atmosphere of nitrogen, hydrogen or vacuum at a temperature 800...1000°C for 1...2 hours Then the obtained contacts are additionally pressed or calibrated, after which the final annealing is carried out in a protective or neutral atmosphere at 450...500°C [ed. St. USSR No. 139379, C22C 1/05, 1960].

The disadvantages of these methods are multi-operation, low quality of the material of powder products due to the relatively high final porosity and low physical and mechanical properties.

The invention is based on the task of obtaining blanks of a lead-antimony alloy with improved physical and mechanical properties without a significant increase in the cost of their manufacture.

The problem is solved by the fact that the lead-antimony alloy is obtained as a result of spark plasma fusion of powders obtained by electroerosive dispersion of SSu-3 alloy waste (GOST 1292-81) in distilled water.

The process of electrical discharge dispersion (EED) is the destruction of a conductive material as a result of local action of short-term electrical discharges between the electrodes.

By adjusting the electrical parameters of the installation for electroerosive dispersion (EED), it is possible to obtain the required amount of powder of a given size and quality for certain periods of time. The powder materials obtained by the electroerosive method are mainly spherical in shape.

The production of a lead-antimony alloy by spark plasma alloying under conditions of rapid heating and a short duration of the working cycle contributes to an increase in physical and mechanical properties compared to industrial alloys from which the initial powder particles were obtained, by suppressing grain growth and obtaining an equilibrium state with submicron and nanoscale grain. The use of the spark plasma alloying method to obtain a lead-antimony alloy from a powder obtained by electroerosive dispersion of the CCu3 alloy will ensure high performance of parts due to the surface uniformity, favorable structure, and low porosity of the product.

The figure 1 shows a diagram of the EED process of waste alloy SSu-3, figure 2 shows the technique and modes of spark plasma alloying of powders, figure 3 shows the microstructure of the lead-antimony alloy, figure 4 shows the spectrogram of the elemental composition of the lead-antimony alloy, figure 5 - diffraction pattern of lead-antimony alloy.

Lead-antimony powder from the waste of the SSu-3 alloy was obtained in the following sequence.

At the first stage, SSu-3 alloy waste was sorted, washed, dried, degreased and weighed. The reactor was filled with a working medium - distilled water, the waste was loaded into the reactor. Mounted electrodes from the same waste alloy SSu-3. The mounted electrodes were connected to a pulse generator. The required process parameters were set: pulse repetition rate, electrode voltage, and capacitor capacitance.

At the second stage - the stage of electroerosive dispersion of wastes of the SSu-3 alloy, the installation was turned on. The process of EED of the waste of the SSu-3 alloy is shown in figure 1. The impulse voltage of the generator 1 is applied to the electrodes 2 and then to the waste of the alloy 3 (the waste of the grids of current collectors of the acid battery of the SSu3 alloy served as electrodes, respectively) in the reactor 4. When the voltage reaches a certain magnitude, an electrical breakdown of the working medium 5 occurs, located in the interelectrode space, with the formation of a discharge channel. Due to the high concentration of thermal energy, the material at the discharge point melts and evaporates, the working medium evaporates and surrounds the discharge channel with gaseous decomposition products (gas bubble 6). As a result of significant dynamic forces developing in the discharge channel and gas bubble, drops of molten material are ejected outside the discharge zone into the working medium surrounding the electrodes and solidify in it, forming drop-like powder particles 7. The voltage regulator 8 is designed to set the required voltage values, and shaker 9 moves one electrode, which ensures the continuous flow of the EED process.

At the third stage, the working fluid with powder is unloaded from the reactor.

At the fourth stage, the solution is evaporated, dried, weighed, packed, packaged. Then the resulting powder was subjected to fusion.

Fusion of lead-antimony powder was carried out in the system SPS 25-10 "Thermal Technology" (USA).

This achieves the following technical result: obtaining a workpiece of lead-antimony alloy with improved physical and mechanical properties without a significant increase in the cost of their manufacture.

Example 1

Lead-antimony powders from the waste alloy SSu3 obtained by electroerosive dispersion in distilled water at the EED [US Pat. 2449859 Russian Federation, IPC C22F 9/14, С23Н 1/02, B82Y 40/00. Installation for obtaining nanodispersed powders from conductive materials [Text] / Ageev E.V. and etc.]; applicant and patent holder Yugo-Zap. state un-t. - No. 2010104316/02; dec. 02/08/2010; publ. May 10, 2012, Bull. No. 13]. When obtaining the powder, the following setup parameters were used: electrode voltage 150–170 V, capacitance of discharge capacitors 45–65.5 μF, pulse repetition rate 75–100 Hz. As a result of the local impact of short-term electric discharges between the electrodes, the material was destroyed with the formation of dispersed powder particles.

The fusion of the obtained powder was carried out in the SPS 25-10 "Thermal Technology" system (USA) at a temperature T=300°C, a pressure P=40 MPa and a holding time t=5 min.

The resulting workpiece lead-antimony alloy was investigated by various methods.

The microstructure of the alloy was studied using a scanning electron-ion (scanning) microscope with field emission of electrons QUANTA 600 FEG (Netherlands). An analysis of the microstructure of the alloy showed that the new alloy has a fine-grained structure, with inclusions in the form of oxygen, a uniform distribution of phases and the absence of significant pores, cracks and discontinuities.

X-ray spectral microanalysis of the alloy was carried out on an energy-dispersive X-ray analyzer manufactured by EDAX (Netherlands) built into a scanning electron microscope QUANTA 200 3D (Netherlands). Based on the analysis of the spectrograms of the elemental composition, it was established that oxygen is contained on the surface of functional alloys, and all other elements Pb, Sb are distributed relatively evenly.

The phase analysis of the alloy was performed on a Rigaku Ultima IV X-ray diffractometer (Japan). An analysis of the diffraction patterns of the phase composition of the alloy under study showed the presence of oxide phases in it: Sb ₂ O ₅ , Pb ₅ O ₈ , and the pure metal phase Pb.

A lead-antimony alloy with improved physical and mechanical properties has been obtained without a significant increase in the cost of its manufacture.

Example 2

Lead-antimony powders from CCu3 alloy wastes were obtained by electroerosive dispersion in lighting kerosene at an EED installation at an electrode voltage of 100–200 V, a discharge capacitor capacitance of 25–65 μF, and a pulse repetition rate of 25–50 Hz. As a result of the local impact of short-term electric discharges between the electrodes, the material was destroyed with the formation of dispersed powder particles.

The fusion of the obtained powder was carried out in the SPS 25-10 "Thermal Technology" system (USA) at a temperature T=260°C, a pressure P=20 MPa and a holding time t=5 min.

Under these conditions, the powder material is not sintered.

Example 3

Lead-antimony powders from SSu3 alloy wastes were obtained by electroerosive dispersion in lighting kerosene at an EED installation on electrodes of 100–200 V, discharge capacitor capacitance 25–65 μF, and a pulse repetition rate of 25–50 Hz. As a result of the local impact of short-term electric discharges between the electrodes, the material was destroyed with the formation of dispersed powder particles.

The resulting powder was fused in the SPS 25-10 Thermal Technology system (USA) at a temperature T=380°C, a pressure P=60 MPa, and a holding time t=10 min. Under these modes, there were shells and friability on the surface of the workpiece.

Claims (1)

A method for producing a lead-antimony alloy from powders obtained by electroerosive dispersion of CCu-type alloy waste in water, characterized in that said alloy is obtained by spark plasma fusion of powders obtained by electroerosive dispersion of SSu-3 alloy waste in water distilled at a temperature of T=300°C , pressure Р=40 MPa and exposure time t=5 min.

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