RU2062811C1 - Method of production of ingots of calcium-containing alloys - Google Patents

Abstract

FIELD: production of ingots of calcium-containing alloys. SUBSTANCE: starting ingredients are alloyed in a metal sleeve placed in a sealed retort filled with inert gas. After cooling to crystallization the overturned sleeve is placed in another sealed retort with inert atmosphere, in which at a repeated heating the alloy is cast into an ingot mould. Alloy casting is accomplished through an intermediate vessel, whose bottom hole is closed by the plug removed by malting, which allows to combine the operations of alloy casting and agitation. EFFECT: facilitated procedure. 1 tbl

Description

 The inventive method relates to the metallurgy of non-ferrous metals and can be used for industrial production of ingots of alloys of active metals, including calcium, oxidized at high temperature.

 Known methods for producing ingots of calcium-containing alloys by reduction from oxides with a carbon-containing reducing agent, submerged-arc alloying, electrolysis of molten salts, followed by discharge into a mold in air or extraction of an alloy with a vacuum ladle into a mold in an atmosphere with a low oxygen content (1,2), These methods are characterized by a low yield the finished product and are applicable to obtain alloys containing up to 46, About at. calcium.

 A known method for producing calcium-containing alloys used in laboratory practice by fusing components in an airtight container in an inert gas environment (2). The method is suitable for the synthesis of alloys with any calcium content, however, it does not solve the problem of extracting the alloy in the form of an ingot.

Another technical solution is known that makes it possible to obtain homogeneous calcium-containing alloys by fusion of the starting components to produce ingots. This is a method of producing a calcium-aluminum alloy, which consists in fusing elemental calcium and aluminum in an inert gas environment by introducing solid dispersed aluminum into a stream of molten calcium at a temperature of 550-1100 ^o C at a certain speed, cooling the alloy to crystallization and obtaining irregularly shaped ingots by knocking out of a melting cup. It is allowed to extract the alloy by casting into a mold or by spraying a liquid alloy in an inert gas stream (3).

Creating a protective atmosphere by displacing air from a melting cup with argon, carbon dioxide or nitrogen with an oxygen content of less than 2 vol. It does not provide complete isolation of a stream of liquid calcium and molten alloy from air, which leads to burning metal. Therefore, the method is applicable to obtain an alloy with a calcium content of not higher than 80 at. with a yield of 85%
The inventive method solves the problem of expanding the upper limit of the calcium content in the ingot of the alloy to increase the yield of the product.

 A method for producing calcium-containing alloys in the form of ingots of a given geometric shape is proposed, which consists in fusing alloy components in a metal cup installed in an airtight retort with an inert atmosphere, cooling to crystallization, removing the alloy into an ingot in a second retort in an inert medium by flowing out of an overturned cup when heated to the mold through an intermediate vessel with a bottom hole closed by a removable plug by melting.

 The difference of the proposed method from the prototype lies in the complete isolation of the metal melt from atmospheric air during alloy formation and casting of the alloy into the mold, and in that the alloy formation process is carried out in static conditions, and the alloy mixing operation is combined with its extraction into the ingot.

 The complete isolation of the high-temperature melt from atmospheric air, achieved by using high-sealed retorts without moving assemblies and mechanisms, allows to obtain alloys with a high calcium content with a yield of more than 95%. Combining the casting and mixing operations leads to the formation of alloy ingots with a uniform composition, and the use of the corresponding molds allows to obtain ingots of a given geometric shape.

 An example implementation of the method.

The preparation of calcium-containing alloys was carried out on equipment designed for the industrial production of calcium ingots, the weight of the charge in each experiment was 60-65 kg The estimated amount of the starting components was loaded into a metal cup, which was placed in a retort. After installing the cover with a sealing gasket, the retort was evacuated to a residual pressure of 0.1 mm Hg. It was checked for leakage, which did not exceed 0.1 mm Hg. Art. per hour, and then filled with argon to a pressure of 0.2 MPa. The assembled retort was installed in a resistance shaft furnace, kept for 2-3 hours at a temperature of 900-1100 ^o C, removed from the furnace and cooled in a vertical rack with subsequent dismantling of the retort and removing the glass with alloy.

To extract the alloy into an ingot, the beaker in an overturned position was placed in a melting beaker with a funnel-shaped bottom, the bottom opening of which was closed with a calcium plug. A melting cup was mounted on the mold and fixed on it with a detachable connection. The assembly was placed in a retort, which was closed by a lid with a sealing gasket. After evacuating the air and filling the retort with argon using the above method, the retort was installed in a resistance furnace heated to a temperature of 1000-1200 ^o C with a glass with alloy placed in the heating zone. Upon reaching the melting temperature, the alloy was poured into a melting cup, kept in it for some time, and then, after melting the cork, merged into the mold.

 During the outflow of the alloy, the alloy was mixed, and holding the alloy in the form of a liquid bath until the cork melted further contributed to the production of a homogeneous alloy.

 After out-of-furnace cooling, the retort was disassembled, the alloy was removed from the ingot mold, and the sample was taken by a single method from the upper, lower, and middle parts of the ingot.

где

среднее арифметическое значение содержания компонентов в слитке сплава,
C₁, C₂, C₃ содержание кальция в верхней, средней и нижней части соответственно,
n количество анализов.The homogeneity of the alloy was estimated by the mean square deviation calculated by the formula

Where

arithmetic mean of the content of components in the alloy ingot,
C ₁ , C ₂ , C ₃ the calcium content in the upper, middle and lower parts, respectively,
n number of analyzes.

 The compositions of the ingots of calcium-containing alloys obtained by the present method are presented in the table.

The table shows that according to the claimed method with the specified temperature and time parameters, it is possible to obtain alloys with a high calcium content, for example 95% homogeneous in composition (the quadratic deviation of the calcium content along the height of the ingot does not exceed 0.9%), with a yield of more than 95%
The possibility of implementing the proposed method is shown by the example of calcium-magnesium and calcium-nickel alloys. However, the above examples do not limit the scope of the proposed method. Obviously, according to the proposed method, it is possible to obtain double and multicomponent calcium alloys with a liquidus temperature of up to 1100 ^o With both from elemental source components and from ligatures.

 The specified method is simple to implement, fireproof, allows you to get ingots of alloys of a given shape with a high content of active metals in high yield. TTT1

Claims (1)

 A method of producing ingots of calcium-containing alloys, including fusion of the starting components in a sealed volume in an inert gas medium, casting into a mold, cooling to crystallization and removing the ingot, characterized in that after the initial components are fused, the melt is cooled to a solid state and re-heated before casting with melting the alloy, while re-heating and casting into the mold is carried out in the same sealed volume.

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