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CN-121990815-A - Metal-carbon complex phase-containing magnesia carbon refractory material and preparation method thereof

CN121990815ACN 121990815 ACN121990815 ACN 121990815ACN-121990815-A

Abstract

The invention relates to the technical field of refractory materials, in particular to a metal-carbon complex phase-containing magnesia carbon refractory material and a preparation method thereof. According to the invention, through SiC-Si-C complex-phase particles, siC is utilized to resist slag and residual Si oxidation for self-repair, and at the same time, triethyl phosphate and triethyl borate are used to modify graphite to generate a BPO 4 coating, and the graphite is not damaged by mild modification, and medium-low temperature physical blocking and high temperature liquid phase sealing are performed. The two construct a multi-scale strengthening system, and effectively inhibit carbon oxidation and slag erosion.

Inventors

  • Qi Mingshuo
  • SONG QINGBIAO
  • LI YUXIN
  • LIU FUYU
  • ZHANG QIANG

Assignees

  • 营口光阳耐火材料有限公司

Dates

Publication Date
20260508
Application Date
20260408

Claims (8)

  1. 1. The magnesium-carbon refractory material containing the metal-carbon composite phase is characterized by comprising, by weight, 60-75 parts of fused magnesia particles, 8-15 parts of silicon-carbon composite phase particles, 8-15 parts of modified crystalline flake graphite, 2-4 parts of aluminum powder, 1-3 parts of elemental silicon powder, 1-2 parts of nano carbon black and 0.3-1.0 part of boron carbide; The silicon-carbon composite particles are SiC-Si-C three-phase composite particles obtained by ball milling and mixing silicon powder and crystalline flake graphite, performing surface activation treatment on tetraethoxysilane and performing high-temperature solid phase reaction sintering, the composite particles take SiC as a main binding phase and contain residual simple substance Si phase and C phase, and the modified crystalline flake graphite is crystalline flake graphite which is jointly modified by triethyl borate and triethyl phosphate.
  2. 2. The metal-carbon composite phase-containing magnesia carbon refractory material according to claim 1, wherein the particle size of the fused magnesia particles comprises 5-8 mm size fraction, 3-5 mm size fraction, 1-3 mm size fraction and 0-1 mm size fraction, and the mass ratio of the fused magnesia particles of the four size fractions is 3:3:2:2.
  3. 3. The metal-carbon complex phase-containing magnesia carbon refractory material according to claim 1, wherein the grain size of the aluminum powder is less than 0.074mm, the grain size of the elemental silicon powder is less than 0.045mm, and the average grain size of the nano carbon black is 30-50 nm.
  4. 4. The magnesium carbonaceous refractory material having a metal-carbon composite phase according to claim 1, wherein said silicon-carbon composite phase particles are prepared by a method comprising the steps of: s11, mixing the silicon powder with the flake graphite fine powder, and drying to obtain mixed powder; S12, placing the mixed powder and zirconia balls in a ball milling tank, adding absolute ethyl alcohol, and ball milling to obtain slurry, separating the slurry from the grinding balls, dropwise adding a surface activation solution containing tetraethoxysilane into the slurry under stirring, simultaneously adding deionized water, and adjusting the pH value with glacial acetic acid; S13, adding a polyvinyl alcohol aqueous solution with the concentration of 5% into the mixed fine powder with the surface activated, granulating and then compacting to obtain a blank; s14, placing the green body in a high-temperature furnace, carrying out sectional sintering under the protection of argon, cooling to room temperature along with the furnace to obtain sintered particles, crushing the sintered particles, and sieving to obtain the silicon-carbon composite particles.
  5. 5. The metal-carbon complex phase-containing magnesia carbon refractory material according to claim 4, wherein in the step S12, the ball-to-material ratio of zirconia balls to mixed powder is 2:1, the solid-to-liquid ratio of the mixed powder to absolute ethyl alcohol is 1:3, the addition amount of the tetraethoxysilane in the surface activation solution containing the tetraethoxysilane is 1.5% of the total mass of the mixed powder, and the molar ratio of the tetraethoxysilane to deionized water is 1:4.
  6. 6. The magnesium carbonaceous refractory material having a metal-carbon composite phase according to claim 1, wherein the method for preparing the modified crystalline flake graphite comprises the steps of: S21, drying the flake graphite fine powder to obtain dried flake graphite fine powder; s22, adding the dried flake graphite fine powder into a mixed solvent containing ethanol and deionized water, regulating the pH value by using glacial acetic acid, and performing ultrasonic dispersion to obtain uniform graphite suspension; S23, heating the graphite suspension under the protection of nitrogen, dropwise adding a triethyl phosphate solution, and stirring; S24, after the reaction is finished, carrying out suction filtration on the suspension slurry to obtain a filter cake, washing the filter cake with absolute ethyl alcohol, and drying to obtain dry powder; S25, heating the dry powder to react under the nitrogen atmosphere, cooling, grinding and sieving to obtain the modified crystalline flake graphite.
  7. 7. The metal-carbon complex phase-containing magnesia carbon refractory material according to claim 6, wherein in the step S23, the triethyl phosphate solution is formed by mixing triethyl phosphate and absolute ethyl alcohol according to a volume ratio of 1:4, the triethyl phosphate is 1-3% of the mass of the fine powder of the flake graphite, the triethyl borate solution is formed by mixing triethyl borate and absolute ethyl alcohol according to a volume ratio of 1:9, and the triethyl borate is 2-4% of the mass of the fine powder of the flake graphite.
  8. 8. A method for preparing a metal-carbon complex phase-containing magnesia-carbon refractory material, applied to preparing the metal-carbon complex phase-containing magnesia-carbon refractory material according to any one of claims 1 to 7, characterized in that the method comprises the following steps: S1, sequentially adding fused magnesia particles, silicon-carbon composite particles and modified crystalline flake graphite into a stirrer, dry-mixing to obtain uniformly distributed aggregate, uniformly mixing aluminum powder, simple substance silicon powder, nano carbon black and boron carbide fine powder to obtain composite fine powder, adding the composite fine powder into the stirrer, and continuously dry-mixing with the aggregate to obtain the magnesia carbon refractory material.

Description

Metal-carbon complex phase-containing magnesia carbon refractory material and preparation method thereof Technical Field The invention belongs to the technical field of refractory materials, and particularly relates to a metal-carbon complex phase-containing magnesia-carbon refractory material and a preparation method thereof. Background The magnesia-carbon refractory material is prepared by using fused magnesia or high-purity sintered magnesia as a main raw material and matching with flake graphite for pressing, has high melting point and high alkaline slag resistance of magnesia, high thermal conductivity and low thermal expansion of graphite, and is widely applied to lining of steel-making key equipment such as converters, electric arc furnaces, ladles and the like. However, under converter converting conditions, the carbon phase is subjected to double erosion of direct oxidation and indirect oxidation, which are mechanically coupled and sequentially progressive in terms of damage. On one hand, the high oxygen partial pressure air flow directly impacts the surface of the furnace lining, and directly burns and reacts with the graphite carbon phase to form an initial decarburization area on the surface layer of the material, on the other hand, feO with high activity in slag permeates into the material along the initial air holes and reacts with the carbon phase in an oxidation-reduction reaction, carbon monoxide gas continuously escapes to break through a matrix structure, a large number of communicated air holes and microcrack networks are formed in the material, and a channel is further provided for deep permeation of slag. With the rapid increase in the interconnected porosity, the infiltrated slag contacts the exposed MgO particles and undergoes a dissolution reaction to form low-melting phases such as calcium forsterite and iron forsterite, which results in a sudden drop in grain boundary strength and exfoliation of the structure. In the prior art, antioxidants such as aluminum powder, silicon powder and boron carbide are generally introduced, so that Al 2O3、MgAl2O4 and other sites can be generated at the matrix level, and a certain oxidation inhibition effect is achieved. However, the reinforcing effect on the phase interface inside the aggregate particles and the improvement effect on the slag wetting resistance of the surface of the aggregate are limited, the interface bonding between the crystalline flake graphite and the matrix depends on phenolic resin carbon, the high-temperature stability of the crystalline flake graphite is inferior to that of an in-situ ceramic bonding phase, and the interface is in preferential failure risk under severe service conditions. Disclosure of Invention (1) Technical problem to be solved The invention aims to provide a magnesium-carbon refractory material containing metal-carbon complex phases and a preparation method thereof, which are used for solving the problems of continuous consumption of double corrosion of carbon phases due to direct oxidation of high oxygen partial pressure air flow and indirect oxidation of FeO in slag under the working condition of converter blowing, and induction of communicated air holes to expand and drive slag to penetrate deeply. (2) Technical proposal In order to achieve the aim, on the one hand, the invention provides a magnesia-carbon refractory material containing metal-carbon complex phase, which comprises the following components, by weight, 60-75 parts of fused magnesia particles, 8-15 parts of silicon-carbon complex phase particles, 8-15 parts of modified crystalline flake graphite, 2-4 parts of aluminum powder, 1-3 parts of elemental silicon powder, 1-2 parts of nano carbon black and 0.3-1.0 part of boron carbide; The silicon-carbon composite particles are SiC-Si-C three-phase composite particles obtained by ball milling and mixing silicon powder and crystalline flake graphite, performing surface activation treatment on tetraethoxysilane and performing high-temperature solid phase reaction sintering, the composite particles take SiC as a main binding phase and contain residual simple substance Si phase and C phase, and the modified crystalline flake graphite is crystalline flake graphite which is jointly modified by triethyl borate and triethyl phosphate. Further, the particle size of the fused magnesia particles comprises 5-8 mm particle size fractions, 3-5 mm particle size fractions, 1-3 mm particle size fractions and 0-1 mm particle size fractions, and the mass ratio of the four particle size fractions of the fused magnesia particles is 3:3:2:2. Further, the particle size of the aluminum powder is smaller than 0.074mm, the particle size of the simple substance silicon powder is smaller than 0.045mm, and the average particle size of the nano carbon black is 30-50 nm. Further, the preparation method of the silicon-carbon composite particles comprises the following steps: s11, mixing the silicon powder with the flake graph