RU2356967C1 - Flux for protective coating of brass melt - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field and can be used at protection of brass melt in ingot-forming equipment of continuous caster. Flux contains frit of fluoric silicate enamel 20-25% and sodium oktaborate is the rest.

EFFECT: defect elimination, appeared during continuous casting of complex alloyed brass.

1 tbl, 3 dwg, 4 ex

Description

The proposed object relates to the field of metallurgy and can be used to protect the brass melt in the mold of a continuous casting machine.

Alloys of heavy non-ferrous metals have a wide variety of properties in the state of melt. This leads to a differentiated approach to the choice of fluxes for melting, as well as casting of these materials. As the chemical composition of copper alloys became more complicated, the question of choosing suitable compositions for protecting the melts from oxidation and gas saturation became more and more difficult. An even more complex issue is the development of flux compositions used for the same purpose not in the furnace space, but in the molds of continuous casting machines. In this case, in addition to protective functions, the composition of the flux should have an additional set of physical and technological properties: the necessary level of thermal conductivity, adhesive and antifriction characteristics. A particularly difficult problem is the selection of flux material for casting brass, since the zinc in their composition is above the temperature of not only melting, but also boiling. That is why in the following review only fluxes used for processing brass melts will be analyzed.

A.S. USSR No. 897876 [1] protected the composition of the coating-refining flux for copper and its alloys. The flux includes sodium fluoride 3-15% and sodium chloride - the rest. The flux is intended for use in a reflective furnace and cannot be used in crystallizers, since its components do not have antifriction ability.

Japanese corporation MITSUBISHI MATERIALS CORPORATION has received Japan patent No. JP7316678 [2] for coating flux for brass-based alloys. The flux consists of zinc oxide and is a chemically stable substance in comparison with copper oxide. Such a flux does not melt on the surface of the melt like glass-based fluxes, the flux does not react with the alloy components like soot and does not pollute the ingot with foreign inclusions. The disadvantage of the flux is the inability to use in molds due to the inability to perform the function of antifriction material.

The firm PROMECOMET in the description of the patent of the Russian Federation No. 2081928 [3] claims the composition of the combined flux for melting brass. Combined flux for brass melting, containing (in bulk parts): chamotte 30-40, expanded vermiculite 30-40, potassium chloride 20-25, borax 5-10. The composition provides an increase in the thermal stability of the flux to 1150-1180 ° C, which leads to a decrease in the content of oxides of heavy non-ferrous metals in the atmosphere of the furnace to 0.40-0.43 mg / cubic meter, the metal content in the slag to 27-28%; the loss of alloying elements is 1.6-2.8% of their content in the composition. The flux is intended solely for the melting process and cannot be used in crystallizers, since its antifriction ability is not known.

The company "FINAO" in the description of the method and device for combined continuous casting and rolling of copper alloys according to the patent of the Russian Federation No. 2188097 [4] mentioned the composition of the protective coating of the melt mirror of the copper alloy. This coating is a calcined petroleum coke and / or pieces of graphite. Judging by the description, the flux is designed to protect the copper melt upon receipt of the copper wire rod. At such plants, semi-finished products from complexly alloyed brass are not obtained; therefore, such a coating composition is not suitable for processing the mentioned materials.

Ural Polytechnic Institute and Revdinsky Non-Ferrous Metals Processing Plant issued USSR No. 1167226 on the composition for the protection of molten copper alloys from oxidation. The flux contains sodium carbonate in an amount of 17-19% and boric acid - the rest. The use of this composition ensured the production of continuously cast billets of acceptable quality from simple brasses such as L63, L68, as well as lead and tin brass. The disadvantage of the analogue is the inability to use flux for the treatment of brass containing such active components as aluminum, manganese, iron, silicon. For example, the presence of sodium carbonate in the flux during interaction with aluminum leads to the formation of complex complexes that excessively increase the viscosity of the flux.

In 2005, the patent of Ukraine No. 8969 [6] protected the production of brass and bronze ingots by continuous or semi-continuous casting. A distinctive feature of this solution is the use of a coating-lubricating flux in the form of carbon black (soot). Soot is a good protective material that creates a reducing atmosphere, but it does not have antifriction properties, especially when casting highly alloyed brass.

The American corporation OLIN CORPORATION received US patent No. 4038068 [7], as well as similar patents in Japan No. JP53120626, UK No. GB1552554, France No. FK2384853, Germany No. DE2713639 and Canada No. CA1089652 for the method of smelting copper alloys containing aluminum as the main alloying element the amount of 2-12%. A coating flux containing 10 ... 90% potassium chloride is proposed, the rest is sodium chloride. However, it is possible to use the method for melting more complex copper alloys containing, for example, up to 30% zinc, up to 10% nickel, up to 15% manganese, up to 3% silicon and in small amounts iron, chromium, zirconium, cobalt. The patent materials indicate the possibility of using flux in the melting of complexly alloyed brass, however, the use of flux to protect melts in the mold of a continuous casting machine is questionable due to unsatisfactory thermal conductivity.

The closest in technical essence and the presence of matching features is the composition of the flux given in the book [8, p.647]. The flux for the protective coating of brass melt contains sodium octaborate.

Industrial experiments have shown that the quality of double brass ingots cast using this flux composition is satisfactory. But the use of such a flux in the continuous casting of billets of highly alloyed brass containing easily oxidizable components (manganese, aluminum, iron, silicon) led to the appearance of defects such as large blockages (external and internal), sagging, non-slit, and also internal cracks.

The technical task of the present invention is the elimination of defects that occur during continuous casting of complex alloyed brass.

The flux for the protective coating of the brass melt contains sodium octaborate and is characterized in that it additionally contains a frit of silicate enamel fluoride in the following ratio of components:

silicate enamel fluoride frit - 20-25%;

sodium octaborate - the rest.

According to the terminology of GOST 24405 [9], the frit of silicate enamel is a vitreous product obtained by granulating a fused charge containing oxides of silicon, boron, sodium, aluminum, etc. Thus, the frit is not just a set of charge materials, but a product obtained due to their heat treatment. In addition, the frit is a granular material, which distinguishes it from the coating and makes it convenient to mix it with other components. The set of oxides that make up the frit of silicate enamel fluoride, in combination with the required amount of sodium octaborate, is found to be suitable for creating the necessary complex of flux properties used in the mold for continuous casting of semi-alloyed brass blanks.

Silica enamel fluoride frit differs from other frits in that it contains from 1 to 6% fluorine. Fluorine forms compounds with enamel components that increase the fluidity of the flux melt. The latter circumstance allows you to choose the necessary flux viscosity at casting temperatures, ensuring its flow into the gap between the mold wall and the crystallizing alloy. Due to this effect, the adhesion of the cast material with respect to the material of the mold wall decreases, internal stresses, and the absence of cracks and blockages are reduced.

Figure 1 shows large surface and internal blockages in an ingot cast using flux according to the prototype (half of the template).

Figure 2 shows half of the transverse template of the ingot cast using flux according to the proposed technical solution.

Figure 3 shows the cracks in the ingot cast using a flux with a frit content outside the declared range.

Example 1 (prototype). Smelted brass LMtsAHKS of the following chemical composition (wt.%): Copper 70.45; 5.44 aluminum; iron 1.79; manganese 6.80; lead 0.86; silicon 2.09; zinc - the rest, when the content of impurities is not more than 0.3. Under conditions of semi-continuous casting of an ingot with a diameter of 215 mm at a temperature of 1170 ° C, sodium octaborate was introduced into the crystallizer provided that the melt mirror was closed. After casting, the quality of the ingot was evaluated by the following parameters: surface condition, the presence of internal blockages, the length of internal cracks. The results of experiment No. 1 are presented in the table from where it can be seen that the quality of the ingot was not satisfactory. 1, large surface and internal blockages are shown on the transverse ingot template

Example 2. In experiment No. 2 and subsequent experiments, the casting was carried out with the same parameters, but the flux based on sodium octaborate was introduced into a fluoride of silicate enamel enamel ESP 212 according to GOST 24405-80. The chemical composition of the frit (wt.%): SiO ₂ 47-53; B ₂ O ₃ 9-16, P ₂ O ₅ no more than 3, TiO ₂ no more than 8, Pe ₂ O ₃ 4-11, MgO no more than 1.2, Na ₂ O 15-20, K ₂ O 1-3 , Fe ₂ O ₃ not more than 5. Preparation of the flux as a whole was carried out by mixing the starting components: sodium octaborate and frit.

Semi-continuous casting results with various fluxes No.
experience Content
frits in
composition
flux% condition
ingot surface Availability
domestic
blockages Length
domestic
cracks, mm
(in the presence of) one 0 Large blockages Large 350 neslitiny blockages influxes 2 10 Large blockages Large 250 neslitiny blockages folding 3 twenty Defects No 10 are absent four 23 Defects No No are absent 5 25 Defects Single No are absent blockage 0.1 mm 6 thirty Influxes Large 320 blockages

The addition of frit in the amount of 10% (experiment No. 2) was insufficient due to the appearance of large blockages in the ingot, neslitin, folding, and large cracks were also observed.

Example 3 (for the proposed facility). In experiments No. 3-5, a flux with a frit content of 20-25% was used and ingots of acceptable quality were obtained. Figure 2 shows the transverse template of the ingot obtained in this case.

Example 4. In experiment No. 6, 30% of the frit was introduced and the ingot deteriorated by influxes, blockages and cracks. Figure 3 shows the end view of the ingot, where cracks are visible in the central part of the ingot.

In this regard, it was found that in order to obtain an acceptable quality of the ingot, the interval of the frit content of fluorine silicate enamel in the flux is 20-25%.

The technical result from the use of the proposed facility is to eliminate defects that occur during continuous casting of complex alloyed brass.

Literature

1. A.S. USSR No. 897876, IPC C22b 15/00. Coating and refining flux for copper and its alloys. / R.V. Chernov, A.A. Andreiiko, O.A. Tsukurov, etc. // Publ. 1982.02.15.

2. Japan Patent No. JP7316678, IPC B22D 7/10; B22D 11/10; B22D 11/111. Covering flux for brass-base alloy / KOUHATA MASANORI; Applicant MITSUBISHI MATERIALS CORP // Publ. 1995-12-05.

3. RF patent No. 2081928, IPC С22С 1/06. Combined flux for brass melting / S.F. Filippov, V.F. Koloskov, D.P. Lovtsov, V.M. Chursin; applicant LLP "PROMECOMET" // Publ. 1997.06.20.

4. RF patent No. 2188097, IPC B22D 11/10. Method and device for combined continuous casting and rolling of copper alloys. / V.Ya. Alekhin, A.Kh. Kambachekov; the applicant LLC "FINAO" // Publ. 2002.08.27.

5. USSR patent No. 1167226, IPC С22С 1/06. Composition for protecting molten copper alloys from oxidation. / R.K. Mysik, Yu.P. Poruchikov, Yu.L. Bunkov, A.G. Titova; applicants Ural Polytechnic Institute and Revdinsky non-ferrous metal processing plant. // Publ. 1985.07.15.

6. Patent of Ukraine No. UA8969, IPC B22D 21/00. Method for the production of brass and bronze ingots by continuous or semi-continuous casting. / A.P. Klyuyev, S.P. Klyuyev, V.Shpakovsky; the applicants are the same // Publ. 08/08/15.

7. US patent No. 4038068, IPC C22b 15/00. Method of melting copper alloys / TYLER DEREK E; DICKINSON DAVID W; DORE JAMES; Applicant OLIN CORP // Publ. 1980-11-18.

8. Special casting methods: Handbook. / Ed. V.A. Efimova. M .: Engineering. 1991.

9. GOST 24405-80. Silicate enamels (frits). Group U 13.

Claims (1)

A flux for the protective coating of a brass melt containing sodium octaborate, characterized in that it additionally contains a frit of silicate enamel fluoride in the following ratio of components,%:
silicate enamel fluoride frit 20-25 sodium octaborate rest

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