SU1286637A1 - Agent for refining aluminium and its alloys - Google Patents

Abstract

The invention solves the problem of cleaning aluminum and its alloys from undesirable impurities, the presence of which affects the final mechanical properties of the metal. According to the invention, the refining agent for aluminum and its alloys consists of hexachlorobenzr and a mixture of inorganic salts. Hexachlorobenzene, under conditions that exist in the molten metal, decomposes with the release of elemental chlorine. Chlorine cleans the molten mass both mechanically (flotation) and chemically, since it combines with some undesirable elements into compounds that go into the spack. Inorganic salts reduce the interfacial tension between the metal and slag, increase the solubility of undesirable impurities in the slag. The recovered some components act as crystallization centers during the casting of aluminum and its alloys, which ensures the emergence of a fine crystalline structure, and thereby improved mechanical properties. The invented remedy may additionally contain additions of fluorides, alkali and alkaline-earth metals, or complex fluorides of rare metals. 1 hp f-ly. C 3 (L

Description

This invention relates to a means for refining aluminum and its alloys.

 The closest to the proposed PS technical essence and the achieved result is a means for refining aluminum and its alloys, containing, wt.%: NaCl 40-55, KC1 40-50, one or more compounds, such as LiCl., BaCl, MgCl2 and CaClj and others (French Application No. 2393071, Cl, C 22 B 21/06, published 02.02.79) 3-15.

However, the known means is characterized by a low quality of the product obtained.

The aim of the invention is to improve the quality of the product.

This goal is achieved by the fact that the agent contains a mixture of hexachlorobenzene and alkali metal chlorides in a ratio of 1: (0.05- -3) and preferably potassium chloride or potassium and sodium chloride in a ratio of 1: 1.

In addition to the above compounds, the agent can contain up to 20% of the compounds from the group consisting of potassium, sodium, calcium, potassium hexafluoroaluminate or sodium fluorides, and mixtures thereof.

An additional component may be up to 40% by weight of additives from the group consisting of sodium or potassium complex fluorides of titanium, boron, zirconium, metallic titanium, an alloy of aluminum and titanium and / or boron, an alloy of aluminum and zirconium, and mixtures thereof. These substances improve strength and ductility. Titanium and zirconium have a positive effect on the evolution of gases, especially hydrogen, from molten aluminum and its alloys.

According to the invention, technical hexachlorobenzene is used, resulting in a number of chlorination processes, where certain polychlorinated hydrocarbons, such as, for example, hexachloroethane, hexachlorobutadiene, hexachlorocyclopentadiene, pentachlorobenzene, octachlorostyrene, etc., can be present as impurities.

The advantages of the proposed solid refining agent lie primarily in the fact that it is stable at normal temperature and the decomposition of hexa

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chlorobenzene in molten aluminum and its alloys is less violent compared to hexachloroethane. As a result, chlorine and aluminum chloride are released in the form of small bubbles, and refining proceeds more perfectly and with higher efficiency, as regards the use of selected chlorine. Particularly good results are achieved when removing dissolved and mainly chemically attached hydrogen. This advantage is manifested in the production of sheets and foils. In the event of incomplete removal of gases, microscopic gas bubbles remain in the casting, which, during rolling, cause rupture of the material and perforation of the foil | Ge produced. Absolutely gas-free aluminum and its alloys acquire the best mechanical properties, such as strength, ductility and corrosion resistance.

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The proposed agent can be applied in solid form in small quantities, best packed in aluminum foil, or, in the case of a complete solution to the problems of equipment, and in the dosage form of a free-flowing mixture. Example 1. 50 wt. including hexachlorobenzene was mixed with 25 weight.h. potassium chloride and 25 weight.h. sodium chloride. The resulting homogeneous mixture was pressed on an isostatic press with a pressure of 150 MPa into 4 kg briquettes. In this form, the agent was used to refine an alloy of aluminum and 2% magnesium. Refining was carried out at 730 C using baskets in which the briquettes were immersed on the bottom of the furnace containing the molten mass. The refining agent was used in an amount of 0.4%. At the end of the refining process, the hydrogen content decreased by

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1 cm kg of alloy. Was obtained material with composition,%: copper 0.02; manganese 0.10) silicon 0.23; iron 0.33j titanium 0.01 magnesium 1.99; aluminum 97.32. The tensile strength increased by 10%, the ductility by 15% compared with the material that was refined using hexa-chloroethane. The alloy had a higher corrosion resistance.

Example 2. 90 weight, h, technical hexachlorobenzene, containing 50

55

chlorobenzene in molten aluminum and its alloys is less violent compared to hexachloroethane. As a result, chlorine and aluminum chloride are released in the form of small bubbles, and refining proceeds more perfectly and with higher efficiency, as regards the use of selected chlorine. Particularly good results are achieved when removing dissolved and mainly chemically attached hydrogen. This advantage is manifested in the production of sheets and foils. In the event of incomplete removal of gases, microscopic gas bubbles remain in the casting, which, during rolling, cause rupture of the material and perforation of the foil | Ge produced. Absolutely gas-free aluminum and its alloys acquire the best mechanical properties, such as strength, ductility and corrosion resistance.

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The proposed agent can be applied in solid form in small quantities, best packed in aluminum foil, or, in the case of a complete solution to the problems of equipment, and in the dosage form of a free-flowing mixture. Example 1. 50 wt. including hexachlorobenzene was mixed with 25 weight.h. potassium chloride and 25 weight.h. sodium chloride. The resulting homogeneous mixture was pressed on an isostatic press with a pressure of 150 MPa into 4 kg briquettes. In this form, the agent was used to refine an alloy of aluminum and 2% magnesium. Refining was carried out at 730 C using baskets in which the briquettes were immersed on the bottom of the furnace containing the molten mass. The refining agent was applied in the amount of 0.4%. At the end of the refining process the hydrogen content decreased by

I am -1

1 cm kg of alloy. Was obtained material with composition,%: copper 0.02; manganese 0.10) silicon 0.23; iron 0.33j titanium 0.01 magnesium 1.99; aluminum 97.32. The tensile strength increased by 10%, the ductility by 15% compared with the material that was refined using hexa-chloroethane. The alloy had a higher corrosion resistance.

Example 2. 90 weight, h, technical hexachlorobenzene, containing 0

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Go,%: Hexachlorobenzene 85, Hexachloroethane 10, Hexachlorobutydien 3, Pentachlorobenzene 1, Hexachlorocyclopentadiene 0.5, Octachlorostyrene 0.5 was mixed with 8 wt. including potassium chloride and 2 wt. including sodium chloride. The mixture was compressed with a pressure of 80 MPa in a briquette weighing 3 kg. The refining of the molten mass of the crude aluminum was carried out as in Example 1 with such a difference that 0.3% of the agent was used and the refining temperature was 740 C. After refining, the aluminum was cast into ingots and the castings were rolled into foils thick 0.10 mm. The porosity of the foil has decreased by 20% compared with a material that has been refined with a similar agent containing hexachloroethane.

Example 3. 60 wt. Part of technical hexachlorobenzene with the composition given in Example 2 was mixed with weight.h,: sodium chloride 15, potassium chloride 15, sodium hexafluoroaluminium 20, and the resulting mixture was compressed by pressure of 60 MPa into briquettes weighing 3 kg. The briquettes were used to refine molten crude aluminum in an amount of 0.45% of the weight of the batch. The refining temperature was in the range of 740-750 C. The briquettes were immersed in molten aluminum using baskets on the bottom of the furnace. By slow decomposition of the refining agent, complete removal of gases from the alloy was achieved (1 content

the prenod has decreased from 3 to 1 cm - kg of aluminum) and the removal of most metallic and non-metallic impurities. A high-quality material with a fine-grained crystal structure, containing, in addition to aluminum, 0.12% silicon, 0.18% iron and 0.023% titanium, was obtained by casting.

: which was more resistant to corrosion and had a higher tensile strength of 188.5 MPa

Example 4. 20 wt. including hexachlorobenzene containing 1% pentachlorobenzene was mixed with parts: potassium chloride 50; potassium hexafluorotitanate 15, powdered metallic titanium 5; tetrafluoride potassium 10. The resulting homogeneous mixture was compressed by pressure 40 MPa into briquettes weighing 3 kg. The tool is specified

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The foot of the composition was applied for refining molten aluminum in an amount of 0.25%. The temperature was within 740-750 ° C. After refining, the hydrogen content decreased by 0.8 cm kg aluminum, silicon by 0.08%, iron by 0.16%. The titanium content was 0.03%, and boron 0.003%. The molten aluminum mixture was processed on -continuous equipment into strips, and rolled onto a 0.006 mm-thick foil. The average degree of porosity was 500 holes per m, which is 10% less than when using such a tool based on hexa-chloroethane.

Example 5. 70 weight.h. hexachlorobenzene was mixed with weight. h. t potassium chloride 10J potassium hexafluorotitanate 10; hexafluoro-aluminum sodium 5; calcium fluoride 5. The resulting mixture was pressed on an isostatic press with a pressure of 50 MPa into 1 kg briquettes. Briquettes were used to refine an aluminum-magnesium alloy. The temperature of refining kept: in the range of 725-735 C. 0.3% of the means per weight of the load was applied. Hydrogen content

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decreased from the original amount of 6 to 1.2 cm. alloy. Alloy composition,%: copper 0.01; magnesium 4.90; manganese 0.10 j silicon 0,27; iron

5 0.32, titanium 0.02 j aluminum 94.38 was molded in the form of ingots and processed by rolling into 7 mm thick tapes. The surface of the rolling tapes was clean, without bubbles, and the edges of the tapes were smooth, without cracks. Tensile strength was 284 MPa.

Claims (2)

1. Means for refining aluminum and its alloys, containing a mixture 5 solid alkali metal chlorides, characterized in that. it additionally contains solid hexachlorobenzene with its relation to alkali metal chlorides, equal to 0 1: (0.05-3.00), in the following ratio of ingredients, wt.%: Hexachlorobenzene Alkali chlorides metals 2. The tool according to claim. 25-96 one, with by that 4-75 tons of l and - as a high-grade alkali metal chloride, it contains potassium chloride or potassium and sodium chlorides at a 1: 1 ratio.