CN112250451B

CN112250451B - Al for blast furnace ceramic cup2OC-AlN solid solution combined corundum refractory material and preparation method thereof

Info

Publication number: CN112250451B
Application number: CN202011009925.4A
Authority: CN
Inventors: 李勇; 吴晓芳; 李宏宇
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2021-10-12
Anticipated expiration: 2040-09-23
Also published as: CN112250451A

Abstract

Blast furnace ceramicAl for cup₂An OC-AlN solid solution combined corundum refractory material and a preparation method thereof, belonging to the field of refractory materials. The raw materials comprise 57 percent of corundum particles with the particle size of 1-3mm, 13 percent of corundum particles with the particle size of 550-600 mu m, 6-26 percent of corundum fine powder with the particle size of 38-45 mu m, 3-18 percent of metal aluminum powder with the particle size of 38-45 mu m, 1-6 percent of silicon nitride powder with the particle size of 38-45 mu m, and additionally, 2-6 percent of bonding agent phenolic resin of the total weight of the raw materials, wherein the content of the metal aluminum is 3 times of that of the silicon nitride. The preparation method comprises the steps of weighing various raw materials according to a formula, uniformly mixing, mixing to obtain pug, then pressing and forming, drying at 200 ℃ for more than 12h, then heating to 550-650 ℃ in a nitrogen atmosphere, keeping the temperature for 6-10h, and then sintering at 1500-1700 ℃ for 3-6 h. The obtained product has apparent porosity of 9-14% and volume density of 2.90-3.10g/cm³And the normal temperature compressive strength is 260-340 MPa. The method has high chemical stability of raw materials, and does not contain carbon and easily hydrated AlN and Al₄C₃The equipment requirement is low, and Al is successfully prepared₂The OC-AlN solid solution is combined with the corundum refractory material, and can be produced in a large scale.

Description

Al for blast furnace ceramic cup2OC-AlN solid solution combined corundum refractory material and preparation method thereof

Technical Field

The invention belongs to the field of refractory materials. In particular to Al for a blast furnace ceramic cup₂OC-AlN solid solution combined corundum refractory material and a preparation method thereof.

Background

Blast furnace iron making is a main iron making mode, and blast furnace refractory materials are corroded by molten iron and slag and also by gas phases such as alkali steam, carbon monoxide and the like in the using process. Meanwhile, the improvement of the iron-making technology and the improvement of the smelting strength of the blast furnace put new requirements on the blast furnace. In order to reduce maintenance cost and avoid economic loss caused by production stoppage, the service life of the blast furnace needs to be prolonged.

The blast furnace ceramic cup hearth furnace bottom structure consisting of the ceramic cup and the carbon brick is a novel hearth furnace bottom structure developed after the comprehensive furnace bottom structure and the water-cooling carbon brick thin furnace structure are combined, has obvious superiority, and is one of comprehensive technologies for realizing the long service life of the blast furnace. As the working surface which is directly contacted with molten iron and slag, the performance of the ceramic cup brick directly influences the long service life of the blast furnace. The ceramic cup brick should have good molten iron erosion resistance, slag erosion resistance and alkali steam erosion resistance, and simultaneously should have a proper heat conductivity coefficient to realize the heat preservation of the furnace hearth on the molten iron, so as to improve the temperature of the molten iron and reduce the energy consumption of ironmaking. At present, the better ceramic cup brick is a foreign ceramic cup brick. Domestic ceramic cup bricks such as composite brown corundum bricks and corundum mullite bricks have obvious effect on improving the temperature of molten iron, but the ceramic cup bricks have poor alkali resistance and slag and molten iron corrosion resistance, and the effect of prolonging the service life of a blast furnace is not obvious. In order to develop the ceramic cup technology better, the ceramic cup brick which can meet the requirement of the blast furnace needs to be developed.

The corundum material has better alkali resistance and slag corrosion resistance, can be used as a base material of the ceramic cup brick, and simultaneously needs to introduce a reinforcing phase with better heat conductivity coefficient to improve the service performance. Al (Al)₂The OC-AlN solid solution has the advantages of high carbide thermal conductivity, small thermal expansion rate, good thermal shock resistance and the like, has high melting point and good high-temperature stability, and is a good reinforcing phase of a corundum material. Early studies by hot pressing AlN, Al at high temperature₄C₃And Al₂O₃Powder mixture of (3) Synthesis of Al₂OC-AlN solid solution, high-temperature high-pressure synthesis conditions, and AlN and Al₄C₃The easy hydration of the sodium silicate limits the industrial production of the sodium silicate. At present, the research shows that the resin is combined with Al-Al₂O₃Al can be obtained from the composite material under the condition of high-temperature nitrogen₂OC-AlN solid solution, but Al with poor high-temperature stability exists in the product₄O₄C. And nitrogen is the only nitrogen source, and uniform nitridation and Al are difficult to realize when the sample size is large₂And (3) synthesizing an OC-AlN solid solution. To obtain large-sized Al₂The OC-AlN solid solution is combined with the corundum refractory material, and a solid nitrogen source needs to be considered to be introduced. Introduction of solid nitrogen source silicon nitride obtains more AlN through reaction with aluminum so as to reduce Al₄O₄C content, and Al is obtained by liquid phase sintering under the action of liquid phase metal₂OC-AlN solid solution. With Al₂The OC-AlN solid solution reinforcing phase is mainly and hardly contains Al₄O₄Al of C₂The OC-AlN solid solution combined corundum refractory material is expected to become a ceramic cup brick meeting the requirement of a blast furnace.

Disclosure of Invention

The invention aims to provide Al for a blast furnace ceramic cup₂OC-AlN solid solution combined corundum refractory material anda preparation method. More AlN is obtained by introducing a solid nitrogen source, namely silicon nitride reacts with aluminum, so that Al is reduced₄O₄C content, and synthesizing Al by liquid phase sintering under the action of liquid phase metal₂OC-AlN solid solution.

Al for blast furnace ceramic cup₂The OC-AlN solid solution combined corundum refractory material is characterized in that: the raw materials comprise, by weight, 76-96% of corundum, 3-18% of metal aluminum powder, 1-6% of silicon nitride powder and 2-6% of binding agent phenolic resin of the total weight of the raw materials, wherein the content of the metal aluminum is 3 times of that of the silicon nitride. The grain proportion of the refractory material will affect the structure and performance, and the pug with reasonable grain composition is not only beneficial to molding, but also beneficial to sintering, and can obtain the refractory material with higher density. In the invention, the granularity of the metal aluminum powder is as follows: 38 μm<Particle size<45 μm; the granularity of the silicon nitride powder is as follows: 38 μm<Particle size<45 μm; the corundum has the following granularity and corresponding weight percentage: 57 percent of corundum particles with the particle size of 1-3mm, 13 percent of corundum particles with the particle size of 550-600 mu m and 4-26 percent of corundum fine powder with the particle size of 38-45 mu m.

Al for blast furnace ceramic cup as described above₂The preparation method of the OC-AlN solid solution combined corundum refractory material is characterized by comprising the following steps: weighing various raw materials according to a formula, uniformly mixing, mixing to obtain pug, then pressing and forming, firstly drying for more than 12h at 200 ℃, then heating to 550-650 ℃ in nitrogen atmosphere, preserving heat for 6-10h, and then sintering for 3-6h at 1500-1700 ℃ to obtain Al₂OC-AlN solid solution is combined with corundum refractory material.

The invention solves the problems of large loss caused by low melting point of Al and large loss of Al and Si in one-step sintering through two-step sintering₃N₄Insufficient reaction, etc. The two-step sintering method disclosed by the invention has the advantages that the surface of Al is nitrided to form AlN by keeping the temperature at 550-650 ℃ for 6-10h, so that an Al @ AlN structure is obtained. With the rise of the temperature, the Al @ AlN structure is damaged, refined Al liquid drops are obtained, and Al and Si are increased₃N₄More AlN is obtained, thereby increasing Al₂Content of OC-AlN solid solution. The designed high-temperature sintering temperature is higher than 1400 ℃, and the reaction activity is improvedProperty, increase Al₂Content of OC-AlN solid solution.

Positive effects of the invention

1. The invention takes silicon nitride, aluminum and corundum which are not easy to hydrate as raw materials to replace aluminum carbide and aluminum nitride which are easy to hydrate to synthesize Al₂OC-AlN solid solution. Al reduction by reaction of solid nitrogen source silicon nitride with aluminum to yield more AlN₄O₄C content, and Al content is reduced by liquid phase sintering under the action of liquid phase metal₂And (3) synthesizing OC-AlN solid solution.

2. The invention replaces one-step sintering by two-step sintering, thereby solving the problems of loss caused by low Al melting point and Al and Si in one-step sintering₃N₄Insufficient reaction, etc. In the two-step sintering, the temperature is kept at 550-650 ℃ for 6-10h, so that the surface of Al is nitrided to form AlN, and an Al @ AlN structure is obtained. At higher temperature, the damage of the Al @ AlN structure introduces refined Al liquid drops, and increases Al and Si₃N₄More AlN is obtained, thereby increasing Al₂Content of OC-AlN solid solution. The sintering temperature is higher than 1400 ℃, the reaction activity is improved, and more Al is obtained₂OC-AlN solid solution.

3. The product obtained by the invention has excellent physical performance indexes, the apparent porosity of the product is 9-14%, and the volume density is 2.90-3.10g/cm³And the normal temperature compressive strength is 260-340 MPa. The product does not contain easily hydrated AlN and Al₄C₃And the reinforcing phase is Al with better high-temperature performance₂The OC-AlN solid solution is mainly almost free of Al with poor high-temperature stability₄O₄C. The product has better high-temperature stability, alkali resistance and slag corrosion resistance, and is expected to become a ceramic cup brick meeting the requirements of blast furnaces.

Drawings

FIG. 1 shows diffraction results of a product obtained in example 1 of the present invention;

FIG. 2 shows diffraction results of the product obtained in example 2 of the present invention.

Detailed Description

Example 1: al for blast furnace ceramic cup₂OC-AlN solid solution combined corundum refractory material andthe preparation method comprises the following raw materials in percentage by weight: 57 percent of corundum particles with the particle size of 1-3mm, 13 percent of corundum particles with the particle size of 550-600 mu m, 14 percent of corundum fine powder with the particle size of 38-45 mu m, 12 percent of metal aluminum powder with the particle size of 38-45 mu m, 4 percent of silicon nitride powder with the particle size of 38-45 mu m and 3.5 percent of binding agent phenolic resin in total weight of the raw materials. Weighing various raw materials according to a formula, uniformly mixing, mixing to obtain pug, then pressing and forming, drying at 200 ℃ for more than 12h, then heating to 580 ℃ under the nitrogen atmosphere, preserving heat for 8h, and then sintering at 1600 ℃ for 3h to obtain the product of the invention. The diffraction results of the obtained product are shown in FIG. 1. The performance indexes of the obtained product are as follows: apparent porosity of 12.3% and volume density of 2.98g/cm³And the normal-temperature compressive strength is 270MPa, and the thermal shock resistance, the erosion resistance, the oxidation resistance and the hydration resistance of the material are all better.

Example 2: the raw materials have the same composition as that of the example 1, and the production process is different, except that: heating to 580 ℃ in nitrogen atmosphere, preserving heat for 8h, and then sintering at 1500 ℃ for 3h to obtain the product of the invention. The diffraction results of the obtained product are shown in FIG. 2. The performance indexes of the obtained product are as follows: apparent porosity of 10.6% and volume density of 3.01g/cm³The normal-temperature compressive strength is 326MPa, and the thermal shock resistance, the erosion resistance, the oxidation resistance and the hydration resistance of the material are all better.

Claims

1. Al for blast furnace ceramic cup₂The OC-AlN solid solution combined corundum refractory material is characterized in that: the raw materials comprise, by weight, 76-96% of corundum, 3-18% of metal aluminum powder, 1-6% of silicon nitride powder, and a bonding agent phenolic resin accounting for 2-6% of the total weight of the raw materials, wherein the content of the metal aluminum is 3 times of that of the silicon nitride;

al for blast furnace ceramic cup₂The preparation method of the OC-AlN solid solution combined corundum refractory material comprises the steps of weighing various raw materials according to a formula, uniformly mixing, mixing to obtain pug, then pressing and forming, drying at 200 ℃ for more than 12h, heating to 550-650 ℃ in a nitrogen atmosphere, preserving heat for 6-10h, and sintering at 1500-1700 ℃ for 3-6h to obtain the Al-doped corundum refractory material₂OC-AlN solid solution bonded steelA jade refractory;

the granularity of the metal aluminum powder is as follows: 38 μm < particle size <45 μm; the granularity of the silicon nitride powder is as follows: 38 μm < particle size <45 μm; the corundum has the following granularity and corresponding weight percentage: 57 percent of corundum particles with the particle size of 1-3mm, 13 percent of corundum particles with the particle size of 550-600 mu m and 6-26 percent of corundum fine powder with the particle size of 38-45 mu m.

2. Al for blast furnace ceramic cup according to claim 1₂The preparation method of the OC-AlN solid solution combined corundum refractory material is characterized by comprising the following steps: weighing various raw materials according to a formula, uniformly mixing, mixing to obtain pug, then pressing and forming, firstly drying for more than 12h at 200 ℃, then heating to 550-650 ℃ in nitrogen atmosphere, preserving heat for 6-10h, and then sintering for 3-6h at 1500-1700 ℃ to obtain the Al₂OC-AlN solid solution is combined with corundum refractory material.