Method for production of refractory parts

FIELD: refractory industry, in particular corundum parts for ferrous and non-ferrous metallurgy.

SUBSTANCE: on the step of batch preparation surface of fused corundum filler spheroid particles is damped with oleic or stearic acid in amount of 0.5-0.0 mass % in respect to total mass of phosphate binder. During agitation fine dispersed intergrinding mixture containing (mass %): Al2O3 47-80, ZrO2-SiO2 20-53, and phosphate binder (e.g. phosphoric acid or aluminum phosphate) is added. Batch contains (mass %): fused corundum filler 50-70; fine dispersed intergrinding mixture 30-50; phosphate binder over 100 % 5-10. Batch is homogenized, formed, solidified in air, baked at decomposition temperature of zircon concentrate, and cooled with isothermal holding at 1100-9000C.

EFFECT: corundum-based articles with improved strength and heat resistance.

7 cl, 2 tbl

 

The invention relates to refractory industry and can be used for the manufacture of refractory products for ferrous and nonferrous metallurgy.

The intensification of technological processes in thermal units ferrous and nonferrous metallurgy dictates the need to create a fire-resistant structural elements from mixtures that allows you to design the structure of the finished products to the target destination with the given consumer of physico-mechanical properties and heat resistance.

In the information sources from a broad class of refractory materials, produce corundum composition with zirconium bearing components, and technological methods are based on the creation of structures of coarse aggregate and alloying additives of various shapes (SU, ed. mon. 296736. Publ. 02.03.1971,, bull. No. 8; SU, ed. mon. 336312. Publ. 21.04.1972,, bull. No. 14; SU, 346281. Publ. 28.07.1972,, bull. No. 23; SU, ed. mon. 398526. Publ. 27.09.1973,, bull. No. 38).

Known methods do not allow the manufacture of large-size products of complex shapes with improved mechanical characteristics and heat resistance.

Closest to the claimed object is solved by the technical task of the prototype - is a method of manufacturing refractory products (SU, 1326570 from 30.07.1987,, bull. No. 28).

The method includes wetting the grains of the oxide suspension, circa the new concentrate in an aqueous solution of lignosulfonate, sodium and potassium, for rolling use lamellar crystals dispersion 5000-7000 cm2/g, mixed with 0.4-2 wt.% aqueous solution of methylcellulose containing 40-60 wt.% Kremenets. From the prepared mass is formed product is dried and then fired at 1580° C.

The disadvantage of this method is the use of aluminum oxide in the form of lamellar crystals, which are poorly pressed and are sintered, which leads to an increased porosity of the products and degradation of mechanical properties and corrosion resistance at operating conditions under the action of the melt and the slag formed. The use of zirconium concentrate natural grain pattern leads to high residual stresses at the phase boundary, which reduce the strength and heat resistance of the composition in comparison with the possibly achievable in this system.

The aim is to develop a method of manufacture of refractory products, ensuring the achievement of the goal of increasing strength and heat resistance of the products on the basis of corundum.

This goal is achieved in contrast to the known method the fact that at the stage of preparation of the charge surface of spheroid particles electrocorundum filler moisten oleic or stearic acid in the amount of 0.5-1 wt.% of the total number of phosphate binder in the mixing process, enter milked starsnow mixture of a joint grinding, containing components, wt.%:

Al2O347-80

ZrO2·SiO220-53,

and phosphate binder at a content of components in the mixture, wt.%:

electrocorundum filler 50-70

fine mixture of joint grinding 30-50

phosphate binder, in excess of 100% 5-10

the mixture is homogenized, molded, carry out air hardening workpieces, calcined at temperatures of decomposition of zirconium concentrate and cool with isothermal aging in the temperature range 1100-900° C.

The essence of the claimed technical solution is in the range of operations and the sequence of their implementation, which together with the selected components allow you to organize the complex process of obtaining a given material structure in the product, which is the main controlling factor for achieving the objectives of the invention.

The introduction of oleic or stearic acid, which are surface-active substances (surfactants)on the surface of spheroid particles electrocorundum filler allows you to avoid coagulation of the fine-grained fractions, evenly distribute phosphate binder and fine mixture of joint grinding, and boundary conditions of concentration due to the fact that the surfactant content below 0.5 wt.% does not allow you to evenly distribute FOS is atoe binder and fine mixture in the amount of electrocorundum filler, results during pressing to pereprisvoeniem cracks when given a specific pressure molding. The upper limit of the content of surfactants in quantities above 1 wt.% it leads to squeezing the walls of the molds when applying a given unit pressure molding.

The phosphate content of the binder is less than 5 wt.% does not allow to obtain a satisfactory transport the strength of the workpiece while moving the stage air hardening, and more than 10 wt.% large blanks are deformed under the action of its weight.

Phosphate binder is injected to increase the strength of the workpieces through the formation of phosphate compounds with the components of the charge in the process of air curing and firing.

Fine phase joint grinding of alumina and zircon concentrate is injected to activate the densification process and physical-chemical processes occurring during the decomposition of zircon concentrate. The maximum content of zircon in a mixture of a joint grinding due to the fact that above this amount in the mixture in the process of decomposition of zircon, there is an excessive silicon oxide, which when cooled undergoes a series of modification reactions, defamatory mechanical properties and thermal stability of the products. The content of zircon in fine mixture below 20 wt.% leads to a sharp drop in heat resistance.

p> The concentration limits of the content of finely dispersed mixture is established experimentally, since the content of its above 50 wt.% leads to reduction in strength and heat resistance, and the content below 30 wt.% leads to an increase in strength and decrease in heat resistance.

Homogenization of the mixture to produce a uniform distribution of the components and the build-up of fine-dispersed mixture of particles of filler.

Shaping is done by any known in the refractory industry way depending on the configuration and geometry.

Firing blanks at temperatures of decomposition of zircon concentrate is carried out for the formation of tetragonal Zirconia structure and silicon dioxide, which forms aluminum oxide multitopology material.

When cooled in the temperature range 1100-900° With the Zirconia tetragonal structure undergoes modification changes and transitions in monoclinic form to increase by 7-8%. As a result of volume changes occur tangential stress (see Amelan, Harcus. Thermal stresses caused by stationary temperature fields. Fizmatlit, 1968), leading to the formation of discontinuous ring-shaped microcracks around the inclusions. To not form secondary cracks required soft the heat mode, that is isothermal exposure, the duration of which is determined by the size characteristics of the products.

As a result of implementation of the technological process can be used:

- as a phosphate binder phosphoric acid, aluminum phosphate, magnesium phosphate, or a mixture thereof with a specific gravity of 1.2-1.65 g/cm3;

- fractional composition of a filler with a particle size of 0.1 to 3 mm;

the particle size of the finely dispersed mixture of a joint grinding 0,002-0,005 mm;

the decomposition temperature of zirconium concentrate in the temperature range 1540-1700° C;

- isothermal exposures when cooling is carried out to complete the transition of Zirconia from tetragonal to monoclinic form.

The proposed method is as follows.

1. Electrocorundum filler with a particle size of 0.1-3 mm moisten the estimated amount of oleic acid by spraying with a spray gun while mixing in a Z-shaped mixer.

2. The estimated number of components of a mixture of alumina, marks GC, and zirconium concentrate is ground to particle size of 0.002-0.005 mm in vibrating mill.

3. Fine mixture and phosphate binder discrete add in the Z-shaped mixer with electrocorundum filled with constant stirring. After suggesting the specified number of components of the charge mixture is homogenized for 20-30 minutes.

4. The resulting mixture is moved into the mold of a given shape and deform under specific pressure 80,0-100.0 MPa.

5. Billet kept in air at room temperature for 24 hours and sent to muffle gas furnace for firing.

6. Heat the billet to a temperature of decomposition of zirconium concentrate during isothermal aging, providing uniform heating of the product, and cool.

7. When the temperature reaches 1100° To reduce the cooling rate so that temperatures of 900° passed fully the process of transformation of the Zirconia tetragonal form in the monoclinic modification. In practice, in the manufacture of large-size blocks with a mass of ~250 kg, isothermal interval time was 6-8 hours.

On the proposed technological scheme were produced in the form of direct No. 5 and V No. 22 brick, refractory blocks of size 600× 200× 100, melting crucibles wide range at the request of consumers.

From a finished product from different points of the volume cut out the samples that were exposed to the test chemical and x-ray methods and standard methods for refractory industry was controlled by the strength and heat resistance. At the same time of the prepared blends were made samples-witnesses, which characterized the ticks were compared with tests on the products. Chemical analysis of material products and specimens showed that the deviation of the content components from the settlement is in the range of accuracy of the methods. X-ray phase analysis showed that in addition to the main phase α - Al2O3the material is mullite and monoclinic Zirconia.

Examples of the method of manufacture and the properties of the products are given respectively in table 1 and 2. The analysis of tables 1 and 2 shows that the goal has been achieved, and the method is practically implemented on industry standard hardware security measures for personnel and the environment, objectively controlled by domestic measuring systems in the manufacture of commercial batches of products of a given phase composition.

Table 2.
Feature productsExampleThe placeholder
 123 
The resistance, the number of thermal cycles of heating and cooling 20-1300°, 20° With(water):    
until the first is th cracks 25322714-17
before destruction10712111262-70
The limit of compressive strength, MPa130165152125-145

1. Method of making refractory articles comprising moistening the grains of the oxide surface-active substance, the introduction of zirconium concentrate and binder, obtaining a mixture, molding, drying and firing, characterized in that at the stage of preparation of the charge surface of spheroid particles electrocorundum filler moisten oleic or stearic acid in the amount of 0.5-1.0% of the total number of phosphate binder, the mixing process is administered discretely phosphate binder and fine mixture of joint grinding, containing components, wt.%:

Al2About347-80

ZrO2.SiO220-53

when the content of components in the mixture, wt. %:

Electrocorundum filler 50-70

Fine mixture of joint grinding 30-50

Phosphate binder in excess of 100% 5-10

the mixture is homogenized, molded, carry out air hardening workpieces, calcined at temperatures of decomposition of zirconium concentrate and cool with isothermal aging in which intervale temperature 1100-900° C.

2. A method of manufacturing a refractory product according to claim 1, characterized in that the fractional composition of electrocorundum filler is in the range of 0.1 to 3 mm.

3. A method of manufacturing a refractory product according to claim 1, characterized in that the particle size of the finely dispersed mixture of a joint grinding is 0,002-0,005 mm

4. A method of manufacturing a refractory product according to claim 1, characterized in that as a phosphate binder use phosphoric acid.

5. A method of manufacturing a refractory product according to claim 1, characterized in that as a phosphate binder use aluminum phosphate.

6. Method of making refractory articles according to claims 4 and 5, wherein the phosphate binder is used with a specific gravity of 1.2-1.65 g/cm3.

7. A method of manufacturing a refractory product according to claim 1, characterized in that the isothermal exposure at the cooling is carried out until a full transition of Zirconia from tetragonal to monoclinic form.



 

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FIELD: refractory industry, in particular corundum parts for ferrous and non-ferrous metallurgy.

SUBSTANCE: on the step of batch preparation surface of fused corundum filler spheroid particles is damped with oleic or stearic acid in amount of 0.5-0.0 mass % in respect to total mass of phosphate binder. During agitation fine dispersed intergrinding mixture containing (mass %): Al2O3 47-80, ZrO2-SiO2 20-53, and phosphate binder (e.g. phosphoric acid or aluminum phosphate) is added. Batch contains (mass %): fused corundum filler 50-70; fine dispersed intergrinding mixture 30-50; phosphate binder over 100 % 5-10. Batch is homogenized, formed, solidified in air, baked at decomposition temperature of zircon concentrate, and cooled with isothermal holding at 1100-9000C.

EFFECT: corundum-based articles with improved strength and heat resistance.

7 cl, 2 tbl

FIELD: designs of glass melting furnaces.

SUBSTANCE: melt and cast materials on base of alumina-zirconium - silica contain, mass %: Al2 O3, 45 - 65; Zr02, 10.0 - 29.0;SiO2, 20.0 - 24.0 at relation SiO2/(Na2O + K2O), 4.5 - 8.0, the balance matters, 0.5 - 4.0. Such materials may be made of rejected products or from recovered waste materials and they may be used for making construction of glass melting furnaces, namely cross like members of regenerators.

EFFECT: lowered cost of raw materials, high operational properties of products.

11 cl, 4 tbl

FIELD: production of ceramic materials; methods of treatment of ceramics by high-temperature deformation; electrical engineering; mechanical engineering; manufacture of ceramic articles working at high temperatures under load.

SUBSTANCE: proposed method includes preparation of blank from ultra-dispersed powders of zirconium dioxide and aluminum oxide, preliminary sintering at temperature of 1300-1550C for no more than 1 h, high-temperature deformation at temperature of 1400-1600C and pressure of 3-10 Mpa and recrystallization annealing in vacuum at residual pressure of 5·10-5 mm Hg and temperature of 1500-1700C.

EFFECT: improved thermo-mechanical properties of ceramic articles.

3 cl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention pertains to production of fireproof products, mainly for glass-melting furnaces. The charge mixture consists of the following components in the given percentage mass ratios: ZrSiO4 8.5-10.5; Al2O3 72.0-75.0; TiO2 5.0-6.5; Cr2O3 5.5-7.0; ZnO 3.5-5.0; H3BO3 0.5-1.0. The products reach breaking point under pressure of 123-128 MPa, and have effective porosity of 0.15-0.2%.

EFFECT: increased durability and lower effective porosity of the products.

1 tbl

FIELD: construction.

SUBSTANCE: invention pertains to composition of charge materials for production of stoves, thermal generating units, and metallurgical equipment. Charge material for production of refractory products contains the following components, wt %: mullite 31.0-34.0; corundum 30.0-32.0; kaolin 21.0-23.0; caustic magnesite 3.0-4.0; zircon 10.0-12.0.

EFFECT: enhanced heat stability of refractory products.

1 tbl

FIELD: construction.

SUBSTANCE: method for production of heat resistant zircon-containing material includes mixing powder of zircon and aluminium represented by powder with fraction of less than 80 micrometre, in ball mill in liquid glass for 1-3 hours, moulding initial stocks and sintering at the temperature of 1600C. Components in charge are in the following ratio, wt %: zircon concentrate 80-90, aluminium powder 10-20.

EFFECT: moulding certain phase composition in ceramic material, providing for high resistance to corrosion.

1 tbl, 3 dwg

FIELD: construction.

SUBSTANCE: charge for production of an alloyed spinel material contains alumina, periclase, magnesium-alumina spinel, chrome oxide and zirconium dioxide, at the following ratio of components, wt %: alumina - 52.8-64.3; periclase - 22.7-25.2; magnesium-alumina spinel - 8.0-10.0; chrome oxide - 2.0-6.0; zirconium dioxide - 3.0-6.0. The alloyed spinel material contains a phase of alloyed spinel with the following composition Mg0.91-1.08(Al0.91-1.01Cr0.019-0.061)2O4 and phase of zirconium dioxide ZrO2, at the following ratio of phases, wt %: Mg0.91-1.08(Al0.91-1.01Cr0.019-0.061)2O4 - 94.0-97.0; ZrO2 - 3.0-6.0.

EFFECT: increased density and strength and reduced porosity of items.

2 cl, 5 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to a method of making articles from refractory ceramic material for use in microwave electronic equipment: furnace muffler, trays and components thereof. The surface of aluminium oxide particles is moistened with a surfactant, the aluminium oxide particles are mixed with kaolin in ratio of 3:1 (by weight) to obtain a homogeneous mixture of given composition, workpieces of the articles are formed by cold moulding, dried at normal temperature and fired in an oxidative medium as follows: raising temperature to 165020C at a rate of 505C/h, isothermic aging at that temperature for 3.00.5 hours and cooling to normal temperature at the same rate. Zirconium hydroxide sol with density of 1100-1180 kg/m3 and thickness of 1-3 mcm is applied onto the fired workpieces, completely dried at normal temperature and fired in an oxidative medium as follows: raising temperature to 165020C at a rate of 1005C/h, isothermic aging at that temperature for 3.00.5 hours and cooling to normal temperature at the same rate.

EFFECT: high thermomechanical strength and, consequently, longer life of articles made from refractory ceramic material when used in microwave electronic equipment and ensuring stability of electrical properties thereof.

4 cl, 11 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to the fireproof industry. It can be applied for making of protective plasters, as well as monolithic linings of high temperature heat units. A fireproof mass for lining of the heat units includes electrocorundum, high-aluminous cement, zircon concentrate, a water solution of sodium polysilicate with the silicate modulus 6.5 with the following component ratio, wt %: electrocorundum 65-87.5; high-aluminous cement 5-10; zircon concentrate 5-20; water solution of sodium polysilicate 2.5-5.

EFFECT: increase of the thermal stability and mechanic properties.

FIELD: chemistry.

SUBSTANCE: method involves anodic dissolving the metallic aluminium in the sodium chloride solution with the concentrationof 290.5 g/l in a coaxial electrolytic cell with electrode areas differing on two or more orders with the anodic current density of 20-160 A/m2 in the presence of zirconium ions in an amount providing the zirconium oxide content in the formed precipitate from 5 to 20 wt %, maintaining the resulting precipitate in the mother liquor for at least 48 hours, filtering and drying the sediment.

EFFECT: method allows to obtain highly dispersed aluminium-zirconium oxide systems with an average particle size of 20-50 nm, which can be used for producing ceramics of special purpose.

2 cl, 1 dwg, 1 ex, 1 tbl

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