RU2285581C1 - Builtup refractory article - Google Patents

Abstract

FIELD: metal continuous casting processes and equipment.

SUBSTANCE: refractory article has at least two parts: main and erosion resistant. Main part is made of charge containing next ingredients, mass %: melt corundum with fraction size less than 1.0 mm, 46.3 - 63.7; graphite, 15.7 - 21.6; crystalline silicon with fraction size less than 0.088 micrometers, 4.6 - 7.8; silicon carbide with fraction size less than 0.2 mm, 2.8 - 6.9; refractory clay, 1.9 - 5.9; powdered phenol binder, 2.7 - 4.6; liquid organic binder, 0.9 - 2.8; technical lignosulfonate, 0.9 -2.8. Charge of erosion resistant part contains, mass %: melt corundum, 69.3 - 81.0; graphite, 4.8 - 7.9; crystalline silicon, 4.8 - 7.9; refractory clay, 1.9 - 5.9; powdered phenol binder, 1.9 - 4.0; liquid organic binder, 1.0 - 5.0. In second variant of invention charge of erosion resistant part contains in addition melt corundum and reactive alumina at next relation of ingredients, mass %; melt corundum, 61.8 - 69.3; graphite, 4.8 - 7.9; crystalline silicon, 4.8 - 7.9; silicon carbide, 4.8 - 7.9; refractory clay, 1.9 -5.9; reactive alumina, 2.9 - 4.0; powdered phenol binder, 1.9 - 4; liquid organic binder, 1.0 - 5.0.

EFFECT: enhanced strength and erosion resistance of article.

4 cl, 2 tbl

Description

The invention relates to the refractory industry, in particular to the technology of manufacturing refractories for continuous casting of metal, and can be used for casting liquid metal, in particular for regulating the casting of metal.

It is known that during continuous casting of metal, one-piece as well as composite refractory products are used, consisting of two parts: the main part of the product and the erosion-resistant part, which serves to prevent erosion of the product in areas of increased wear. Whole products made on the basis of one composition of the Al ₂ O ₃ -C system are inferior in terms of resistance to composite products with an erosion-resistant layer.

A refractory product for casting metal should have the following properties: the main part should have low porosity, high corrosion resistance, sufficient mechanical strength, erosion-resistant part - high erosion resistance, which is ensured by high mechanical strength and low porosity.

A composite refractory product for casting liquid metal is known, consisting of two parts: basic based on Al ₂ O ₃ -C (chemical composition: Al ₂ O ₃ - 52%, C - 20%, SiO ₃ - 13%) and erosion resistant parts based on MgO-C (MgO - 73%, C - 20%) (Fachberichte Huttenpraxis Metallweiterverarbeitung. Vol. 23, No. 4, 1985, p. 256, Table 3).

The disadvantage of this composite refractory product is the high porosity, low oxidation resistance of the product body, as well as the low erosion resistance of the head part.

Closest to the totality of features (prototype) to the proposed is a composite refractory product for casting metal, consisting of at least two parts: the main and erosion-resistant. The main part is made of a mixture containing the following components, wt.%: Fused corundum fraction 1.0-0 mm 55-75, graphite 15-28, silicon crystalline fraction less than 0.088 mm 1-8, silicon carbide fraction less than 0.2 mm 1-6, borosilicate glass frit fractions of less than 0.088 mm 1-6, phenolic powder binder 2.5-4, liquid organic binder (in excess of 100%) 1-5. Silicon, silicon carbide, and borosilicate glass frit are antioxidant additives. The charge of the erosion-resistant part contains the following components, wt.%: Fused periclase fraction 0.5-0 mm 65-80, graphite 15-25, aluminum fraction less than 0.5 mm and / or silicon crystalline fraction less than 0.088 mm 1-8 , silicon carbide fraction less than 0.2 mm 1-6, phenolic powder binder 2.5-4, liquid organic binder (in excess of 100) 1-5 (RF Patent No. 2226450, 08/06/2002, B / 22 D 41/54)

The main disadvantage of this composite refractory product, as well as the aforementioned analogue, is the tendency to crack during operation due to the difference in the coefficients of thermal expansion of the material of the main and erosion-resistant layer, which leads to an emergency termination of the process of continuous casting of steel and, as a result, a large economic to losses. A composite refractory product, due to the content of the main layer of low-melting borosilicate frit in the material, undergoes only low-temperature heat treatment (1150-1200 ° C), during which it is not possible to identify the tendency of the products to crack along the layer boundary. Used solid and liquid organic binders belong to the group of phenol-formaldehyde resins: phenolic powder binder - novolac type resin, liquid bakelite - resole type resin. During carbonization, these resins form a very strong and rigid carbon frame, unable to withstand the bending loads that arise during the operation of products, which also contributes to their destruction.

The problem to which the invention is directed, is to reduce porosity and increase the oxidation resistance of the material for the body, increase the erosion resistance of the head of the composite refractory products and increase the resistance of the products to cracking.

The problem is solved due to the fact that the composite refractory for casting metal, consisting of at least two parts: the main and erosion-resistant, made, in contrast to the prototype, from a material based on Al ₂ O ₃ -C. The main part is made of a mixture containing the following components, wt.%: Fused corundum fraction less than 1.0 mm 46.3-63.7; graphite 15.7-21.6; silicon crystalline fractions less than 0.088 microns 4.6-7.8; silicon carbide fractions less than 0.2 mm 2.8-6.9; refractory clay 1.9-5.9; binder phenolic powder 2.7-4.6; liquid organic binder 0.9-4.6; technical lignosulfonate 0.9-2.8. The charge of the erosion-resistant part additionally contains refractory clay in the following ratio of components, wt.%: Fused corundum fraction less than 1.0 mm 69.3-81.0; graphite 4.8-7.9; silicon crystalline fractions less than 0.088 microns 4.8-7.9; refractory clay 1.9-5.9; binder phenolic powder 1.9-4.0; liquid organic binder 1.0-5.0. The solution to this problem is achieved by adding to the mixture an erosion-resistant part of reactive alumina and silicon carbide, in the following ratio of components, wt. %: fused corundum fraction less than 1.0 mm 61.8-69.3; graphite 4.8-7.9; silicon crystalline fractions less than 0.088 microns 4.8-7.9; silicon carbide fractions less than 0.2 mm 4.8-7.9; refractory clay 1.9-5.9; reactive alumina 2.9-4.0; binder phenolic powder 1.9-4.0; liquid organic binder 1.0-5.0.

The refractory clay introduced into the blends of the main and erosion-resistant parts performs, when pressed, the role of an additional binder, and when fired, an antioxidant additive. The addition of technical lignosulfonate to the batch of the main part increases the binding properties of refractory clay during pressing, and during firing, due to the presence of ash in graphite containing low melting compounds of sodium, potassium and calcium, which reduce its sintering temperature.

The use of a combined organo-mineral binder promotes the formation of two interpenetrating matrices in products: carbon and ceramic, which leads to an increase in the bending strength of the material.

The addition of the erosion-resistant part of reactive alumina to the charge — finely dispersed corundum with an average part diameter of about 2 μm — reduces the onset temperature of mullite formation in the binder, increases the strength, reduces porosity, and ensures high erosion resistance. Introduction to the mixture of silicon carbide - an antioxidant additive increases erosion resistance, respectively increasing strength and reducing porosity of the product.

It turns out a composite refractory product with the necessary set of operational properties. In addition, compared with the prototype, the material of the erosion-resistant part of the claimed composition is more compatible with the material of the main part of the product due to the similarity of their compositions (all of them are materials of the same Al ₂ O ₃ -С system).

The manufacturing process of a composite refractory product is implemented as follows.

The following materials were used for the manufacture of composite refractory products: fused corundum fractions of 1.0-0 mm according to TU 2-036-0224450-022-90, graphite grade GT-1 according to GOST 4596-75, crystalline silicon, grades KR-1, KR- 2 according to GOST 5279-74, fractions less than 0.088 mm, silicon carbide grades 54C with grain size 160-6 according to TU 2-036-0220937-004-90, fractions less than 0.2 mm, TFP - phenolic powder binder TU 6-0575-1768- 35-94 grade SFP-012 A with a free phenol content of less than 1%, refractory clay of the Novorayiskoye field DN-1 according to TU 4322-7-00190503-061-96, reactive alumina manufactured by BKO OJSC, ethyl cello technical solv according to GOST 8313-88, technical urotropin grade C according to GOST 1381-73, technical furfuryl alcohol. All components of industrial production.

For the manufacture of the main part of the product, a mixture of the following composition is prepared, wt.%:

Fused corundum 59.9 Refractory clay 2.9 Graphite 19.3 Silicon 5.8 Silicon carbide 4.9 Phenolic Binder Powder 3.9 Technical lignosulfonate 1.4 Liquid Organic Binder 1.9

Table 1 presents the composition of the charges and the technical characteristics of the samples for the main part of the composite product.

For the manufacture of erosion-resistant parts of the product, a mixture of the following composition is prepared, wt.%:

Fused corundum 74.8 Graphite 6.8 Silicon 7.8 Refractory clay 4.8 Phenolic Binder Powder 2.9 Liquid Organic Binder 2.9

With the addition of reactive alumina and silicon carbide to the erosion-resistant part of the product, the mixture is prepared as follows:

Fused corundum 68.9 Graphite 6.8 Silicon 6.8 Silicon carbide 3.4 Refractory clay 4.8 Reactive Alumina 2.9 Phenolic Binder Powder 3.4 Liquid Organic Binder 2.9

Table 2 presents the compositions of the charges and the technical characteristics of the samples for the erosion-resistant part of the composite product.

Separately prepared blends of the main and erosion-resistant parts were separately poured into the mold, vibrated, and evacuated. Products were formed with a transition layer consisting of masses of compositions for the main and erosion-resistant parts, taken in a 1: 1 ratio. Raw composite refractory products were extruded by hydrostatic molding at a pressure of at least 90 MPa. Raw roasting was carried out in a muffle with coke filling at a temperature of 1450 ° C.

The finished composite refractory product, the monoblock stopper, is used to control the casting of metal in continuous steel casting plants. The products were successfully tested at the largest metallurgical plants in Russia (Severstal, Novolipetsk, Magnitogorsk), providing continuous casting of metal of various grades for 15 hours and in the amount of up to 1900 tons through one stream.

Table 1 The composition of the mixture and the technical characteristics of the samples for the main part of the composite product. Name of raw materials The composition of the mixture one 2 3 four Prototype Melted corundum, fr. 1.0-0 mm 48.1 52.7 59.9 62.5 52,4 Graphite 22.1 21.1 19.3 17.3 26.6 Crystalline silicon, FR. <0,088 mm 7.7 6.7 5.8 4.8 7.6 Silicon Carbide, FR <0.2 mm 6.7 5.7 4.9 3.8 3.8 Refractory clay 6.7 5.7 2.9 4.8 - Phenolic Binder Powder 4.8 3.8 3.9 2.9 3.8 Liquid Organic Binder 2.9 2,4 1.9 1,0 Technical lignosulfonate 1,0 1.9 1.4 2.9 - Borosilicate glass frit, FR <0.088 mm - - - - 1,0 Liquid Bakelite (over 100%) - - - - 4.8 Open porosity,% 10-12 9.5-11.5 8.0-9.0 11-13 11.3 The limit of compressive strength, MPa 38-45 40-48 42-62 35-40.5 23.3 Bending Strength, MPa 10-13 11-14.5 16-18 12-15 There is no data The coefficient of linear thermal expansion, deg ^-1 X 10 ^-7 50.51 49.58 49.49 55.45 56.34 Oxidation 1300 ° С - 2 hours,% 4.8 4.0 2.0 4,5 4.9 Slag resistance,% 4.2 3,5 2.2 5,4 There is no data

table 2 The compositions of the charges and the technical characteristics of the samples for the erosion-resistant part of the composite product. Name of raw materials The composition of the mixture one 2 3 four Prototype Fused corundum, fr. 1.0-0 mm 74.8 68.9 69.1 77.5 - Fused periclase, fr. 0.5-0 mm - - - - 64.0 Graphite 6.8 6.8 7.7 4.9 17.5 Crystalline silicon, FR. <0,088 mm 7.8 6.8 9.6 5.8 5,0 Silicon Carbide, FR <0.2 mm - 3.4 3.8 2.0 6.0 Refractory clay 4.8 4.9 1.9 5.8 - Reactive Alumina - 2.9 - - Aluminum metal (APVP), fr. <0.2 mm - - - 3.0 Phenolic Binder Powder 2.9 3.4 3.8 2.0 3,5 Ethylene glycol - - - - 1,5 Liquid Organic Binder 2.9 2.9 3.8 2.0 - Technical lignosulfonate (over 100%) - - - - - Open porosity,% 12-13 11-12 15-16.5 14-15 14.7 The limit of compressive strength, MPa 63-68 65-70 50-60 45-55 18.3 Bending Strength, MPa 8-9 9-10 8-9 7-8 There is no data The coefficient of linear thermal expansion, deg ^-1 X 10 ^-7 50.11 51.24 59.24 56.19 89.1 Metal Resistance,% 0.7 0.8 1.9 1,6 1,5

Claims (4)

1. Composite refractory product for metal casting, containing at least the main and erosion-resistant parts, the main part is made of a mixture including fused corundum fractions of less than 1.0 mm, graphite as a carbon-containing material, an antioxidant additive of silicon the crystalline fraction is less than 0.088 μm and the silicon carbide fraction is less than 0.2 mm, the liquid binder and powder phenolic binder, and the erosion-resistant part is made of a mixture including graphite as a carbon-containing material, antioxidant a silicon excipient with a crystalline fraction of less than 0.088 μm, a liquid binder and a phenolic powder binder, characterized in that the charge of the main part additionally contains refractory clay as a plasticizing additive and technical lignosulfonate in the following ratio of components, wt.%: Fused corundum 46.3-63.7 Graphite 15.7-21.6 Crystalline silicon 4.6-7.8 Silicon carbide 2.8-6.9 Refractory clay 1.9-5.9 Phenolic Binder Powder 2.7-4.6 Liquid Organic Binder 0.9-4.6 Technical lignosulfonate 0.9-2.8 and the charge of the erosion-resistant part additionally contains fused corundum and refractory clay in the following ratio of components, wt.%: Fused corundum 69.3-81.0 Graphite 4.8-7.9 Crystalline silicon 4.8-7.9 Refractory clay 1.9-5.9 Phenolic Binder Powder 1.9-4.0 Liquid Organic Binder 1.0-5.0 2. The composite refractory product according to claim 1, characterized in that the liquid organic binder is a solution of novolac resin with the addition of urotropine in a complex organic solvent, including furfuryl alcohol and ethyl cellosolve in the following ratio, wt.%: Phenolic Binder Powder 15-20 Urotropin 5-8 Furfuryl alcohol 40-60 Ethyl cellosolve 20-40 3. Composite refractory product for metal casting, containing at least the main and erosion-resistant parts, while the main part is made of a mixture comprising fused corundum fractions of less than 1.0 mm, graphite as a carbon-containing material, an antioxidant additive of silicon the crystalline fraction is less than 0.088 μm and the silicon carbide fraction is less than 0.2 mm, the liquid binder and powder phenolic binder, and the erosion-resistant part is made of a mixture including graphite as a carbon-containing material, antioxidant exemplary silicon additive of crystalline fraction less than 0.088 microns and silicon carbide fraction less than 0.2 mm, liquid binder and powder phenolic binder, characterized in that the charge of the main part additionally contains refractory clay as a plasticizing additive and technical lignosulfonate in the following ratio of components, wt .%: Fused corundum 46.3-63.7 Graphite 15.7-21.6 Crystalline silicon 4.6-7.8 Silicon carbide 2.8-6.9 Refractory clay 1.9-5.9 Phenolic Binder Powder 2.7-4.6 Liquid Organic Binder 0.9-4.6 Technical lignosulfonate 0.9-2.8 and the charge of the erosion-resistant part additionally contains fused corundum and reactive alumina in the following ratio of components, wt.%: Fused corundum 61.8-69.3 Graphite 4.8-7.9 Crystalline silicon 4.8-7.9 Silicon carbide 4.8-7.9 Refractory clay 1.9-5.9 Reactive Alumina 2.9-4.0 Phenolic Binder Powder 1.9-4.0 Liquid Organic Binder 1.0-5.0 4. The composite refractory product according to claim 3, characterized in that the liquid organic binder is a solution of novolac resin with the addition of urotropine in a complex organic solvent, including furfuryl alcohol and ethyl cellosolve in the following ratio, wt.%: Phenolic Binder Powder 15-20 Urotropin 5-8 Furfuryl alcohol 40-60 Ethyl cellosolve 20-40