Corundum-tin oxide composite refractory material and its preparation method and application

Abstract

The present invention discloses a corundum-tin oxide composite refractory material, its preparation method, and application, relating to the field of refractory materials technology. The technical solution comprises the following components in percentage by mass: 30-35% corundum particles with a particle size of 0.1 mm < ≤ 1 mm; 20-25% corundum particles with a particle size of 1 mm < ≤ 3 mm; 15-20% corundum particles with a particle size of 3 mm < ≤ 6 mm; 5-15% alumina fine powder; 5-15% tin oxide clinker fine powder; 3-5% yttrium-stabilized zirconium fine powder; 3-5% calcium aluminate cement fine powder; 0.2-1% water reducer; and in the tin oxide clinker fine powder, SnO2> 98 wt.%, Fe2O3< 0.2 wt.%, Sb2O3< 1.5 wt.%, CuO< 0.6 wt.%, and a bulk density of ≥ 6.6 g / cm3. 3 The corundum-tin oxide composite refractory material of the present invention has good resistance to glass melt corrosion, thermal shock resistance and high-temperature volume stability.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and in particular to a corundum-tin oxide composite refractory material and a preparation method and application thereof. Background Art

[0002] Although traditional corundum refractory materials have high hardness and excellent high-temperature resistance, they are susceptible to erosion and penetration in glass melting furnaces containing chemical components such as fluorine and boron. This erosion and penetration can cause the material structure to peel or fail, thereby shortening the service life of the refractory material. In addition, under the working conditions of rapid cooling and heating, corundum materials have a high thermal expansion coefficient (about 8.9×10 -6 / K), its thermal stability is poor and it is prone to cracking, which further reduces the service life of the product.

[0003] In industrial furnaces, lining materials must withstand the harsh environment of high temperatures and large temperature fluctuations, making thermal shock resistance a key performance characteristic. Furthermore, these materials must withstand the erosion of various atmospheres within the furnace. However, the weaknesses of conventional corundum refractories directly limit their effectiveness and scope of application in furnaces.

[0004] Although traditional chromium-containing refractories (such as chrome corundum bricks) have good corrosion resistance, they will form Cr at high temperatures. +6 , which poses a serious risk of pollution to the use environment and human health. Therefore, these materials have serious problems in terms of environmental protection and safety.

[0005] In order to solve the problem of insufficient erosion resistance and thermal shock resistance of corundum refractory materials, it is necessary to further improve them to enhance their comprehensive performance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology, provide a corundum-tin oxide composite refractory material and its preparation method and application, and solve the problem of chromium corundum bricks Cr for glass kilns. +6 The product has the characteristics of resistance to glass liquid and molten salt corrosion, thermal shock resistance and good high temperature stability.

[0007] The technical solution of the present invention is:

[0008] In a first aspect, the present invention provides a corundum-tin oxide composite refractory material comprising the following components in percentage by mass, wherein the total mass of the remaining components excluding the water reducer is calculated as 100%, and the water reducer is calculated as a percentage of the total mass of the remaining components:

[0009] 30-35% of corundum particles with a particle size of 0.1mm<≤1mm;

[0010] 20-25% of the corundum particles with a particle size of 1mm<≤3mm;

[0011] 15-20% of corundum particles with a particle size of 3mm<≤6mm;

[0012] Alumina fine powder 5-15%;

[0013] Tin oxide clinker fine powder 5-15%;

[0014] Yttrium stabilized zirconium fine powder 3-5%;

[0015] Calcium aluminate cement fine powder 3-5%;

[0016] Water reducing agent 0.2-1%;

[0017] In the tin oxide clinker fine powder, SnO2>98wt.%, Fe2O3<0.2wt.%, Sb2O3<1.5wt.%, CuO<0.6wt.%, and the bulk density is ≥6.6g / cm 3 .

[0018] Preferably, the corundum particles are sintered corundum or white corundum, Al2O3>99wt.%, Fe2O3<0.2wt.%, and bulk density>3.5g / cm 3 .

[0019] Preferably, the total content of ZrO2 and HfO2 in the yttrium-stabilized zirconium fine powder is greater than 90 wt.%, Y2O3 is greater than 8 wt.%, Fe2O3 is less than 0.1 wt.%, SiO2 is less than 0.3 wt.%, and the bulk density is greater than 4.5 g / cm 3 .

[0020] Preferably, calcium aluminate cement fine powder is used as the binder, wherein Al2O3 72-82wt.%, CaO 18-25wt.%, the main mineral phase is CA2, and the secondary mineral phase is CA.

[0021] Preferably, the water reducer is one or both of sodium hexametaphosphate and sodium polyacrylate.

[0022] Preferably, the particle size of the alumina fine powder is less than 44 μm, the particle size of the tin oxide clinker fine powder is less than 88 μm, the particle size of the yttrium-stabilized zirconium fine powder is less than 44 μm, and the particle size of the calcium aluminate cement fine powder is less than 44 μm.

[0023] In a second aspect, the present invention provides a method for preparing the above-mentioned corundum-tin oxide composite refractory material, comprising the following steps:

[0024] S1 mixing: first dry-mix corundum particles, alumina fine powder, tin oxide clinker fine powder, yttrium-stabilized zirconium fine powder and calcium aluminate cement fine powder, then add water reducer and water and mix to obtain mud;

[0025] S2 vibration molding: inject the clay into the mold and vibrate to form the green body;

[0026] S3 Drying and Firing: After the formed green body is solidified, it is demoulded, and after natural curing and drying, it is fired to obtain a corundum-tin oxide composite refractory material.

[0027] Preferably, in step S1, water accounts for 6-7% of the total mass of the remaining components except the water reducer, the dry mixing time is 3-5 minutes, and the kneading time is 3-5 minutes; in step S2, the vibration molding time is 3-5 minutes.

[0028] Preferably, in step S3, the curing time is 2-6 hours, demoulding is performed 18-24 hours after curing, the natural curing time is 3-5 days, the drying temperature is 120-180°C, the drying time is 12-24 hours, the firing temperature is 1450-1550°C, and the holding time is 12-24 hours.

[0029] In a third aspect, the present invention provides an application of the above-mentioned corundum-tin oxide composite refractory material, which is used as a refractory material in the area in contact with molten glass in a glass furnace.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention utilizes corundum particles of varying particle sizes and tin oxide clinker fine powder made from recycled tin oxide to form a composite. By introducing SnO2 and utilizing the interfacial interaction between SnO2 and Al2O3, a dense composite structure is formed, enhancing the refractory's resistance to glass penetration and erosion. Furthermore, by incorporating fine calcium aluminate cement powder in addition to SnO2, the vibration-molded green body exhibits high strength. At high temperatures, the tin oxide reacts in situ with the calcium aluminate cement to form spinel-type CaSnO3. This new phase enhances the material's internal bonding strength, reduces apparent porosity, and significantly improves sintering performance.

[0032] 2. This invention combines corundum with tin dioxide and adds yttrium-stabilized zirconium fine powder, leveraging its phase transformation toughening effect to enhance the thermal shock resistance of the refractory. The resulting corundum-tin oxide composite refractory can be widely used in various industrial furnaces below 1550°C. It exhibits high high-temperature stability, resists cracking and shedding, and exhibits advantages such as high strength, excellent thermal shock resistance, high-temperature resistance, and resistance to erosion by molten glass.

[0033] 3. The corundum-tin oxide composite refractory material of the present invention does not pollute the kiln and the environment during use in the kiln, meets the environmental protection requirements of national policies, and can replace most chromium corundum refractory materials with certain pollution. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0035] In the following examples and comparative examples, the chemical compositions of corundum particles, alumina fine powder, tin oxide clinker fine powder, yttrium-stabilized zirconium fine powder, calcium aluminate cement fine powder, and pure tin oxide fine powder are shown in Table 1:

[0036] Table 1 Chemical composition of each raw material

[0037]

[0038] The preparation method of the corundum-tin oxide composite refractory material in the following embodiment comprises the following steps:

[0039] S1 Mixing: First, pour the corundum particles, alumina fine powder, tin oxide clinker fine powder, yttrium-stabilized zirconium fine powder and calcium aluminate cement fine powder into a cone mixer and dry mix for 3-5 minutes. Then, add the water reducer and water into a high-pressure mixer and mix for 3-5 minutes to obtain a slurry.

[0040] S2 vibration molding: inject the clay into the mold and vibrate to form the green body;

[0041] S3 Drying and Firing: The formed green body is cured for 2-6 hours, demolded after 18-24 hours, naturally cured for 3-5 days, dried at 120-180°C for 12-24 hours, fired at 1450-1550°C, and kept warm for 12-24 hours to obtain a corundum-tin oxide composite refractory material.

[0042] The performance test of corundum-tin oxide composite refractory material is carried out as follows:

[0043] (1) Bulk density and porosity: Tested in accordance with GB / T 2997-2015 Test method for bulk density, apparent porosity and true porosity of dense shaped refractory products;

[0044] (2) Compressive strength at room temperature: Tested in accordance with GB / T 5072-2008 Test method for compressive strength of refractory materials at room temperature;

[0045] (3) Thermal shock resistance: Tested in accordance with GB / T 30873-2014 Test method for thermal shock resistance of refractory materials;

[0046] (4) Erosion resistance: Tested in accordance with JC / T 806-2013 Test method for static erosion resistance of refractory materials for glass melting furnaces.

[0047] The raw material composition, process conditions and performance test results of the corundum-tin oxide composite refractory materials of Examples 1-3 are shown in Table 2, wherein the total mass of the remaining raw materials except the water reducer and water is calculated as 100%, and the water reducer and water are calculated as a percentage of the total mass of the remaining raw materials.

[0048] Table 2 Raw material composition, process conditions and performance test results of the corundum-tin oxide composite refractory materials of Examples 1-3

[0049]

[0050] The raw material composition, process conditions and performance test results of the corundum-tin oxide composite refractory materials of Comparative Examples 1-5 are shown in Table 3, wherein the total mass of the remaining raw materials except the water reducer and water is calculated as 100%, and the water reducer and water are calculated as a percentage of the total mass of the remaining raw materials.

[0051] Table 3 Raw material composition, process conditions and performance test results of the corundum-tin oxide composite refractory materials of Comparative Examples 1-5

[0052]

[0053] As can be seen from Table 2, the apparent porosity of the corundum-tin oxide composite refractory prepared in Examples 1-3 of the present invention is less than 20%, and the bulk density is greater than 3.25 g / cm 3 , 1100°C water-cooled thermal shock test number > 30 times; 1450°C × 24h glass erosion rate < 0.1mm / 24h. It can be seen that the corundum-tin oxide composite refractory materials prepared in Examples 1-3 of the present invention have the characteristics of high density, good glass erosion resistance, and good thermal shock resistance.

[0054] As shown in Tables 2-3, Comparative Example 1, which uses mullite powder instead of the tin oxide clinker fine powder and yttrium-stabilized zirconium fine powder in Example 1, significantly reduces the number of 1100°C water-cooled thermal shock tests for the prepared corundum refractory to 15. Furthermore, its glass erosion resistance is poor, reaching a rate of 0.46 mm / 24 h. The softening temperature under 0.2 MPa load decreases from 1578°C to 1518°C, indicating reduced high-temperature resistance. This is due to the addition of tin oxide clinker fine powder and yttrium-stabilized zirconium fine powder in Example 1. The tin oxide clinker fine powder exhibits strong erosion resistance. At high temperatures, tin oxide reacts in situ with calcium aluminate cement fine powder to form spinel CaSnO3, enhancing internal bonding, promoting sintering performance, and improving erosion resistance. The yttrium-stabilized zirconium is uniformly distributed in the matrix, producing a phase transformation toughening effect at high temperatures, inhibiting crack propagation. The simultaneous solid solution strengthening effect of tin oxide and yttrium-stabilized zirconium further enhances the material's crack propagation resistance and improves its thermal shock resistance. The material system of Comparative Example 1 is Al2O3-SiO2-CaO, and the melting point of the three is about 1510°C, which reduces the high-temperature performance of the material.

[0055] As shown in Tables 2-3, compared to Example 1, Comparative Example 2 reduced the content of yttrium-stabilized zirconium fine powder, resulting in a reduction in the number of 17 1100°C water-cooled thermal shock tests for the refractory. This is primarily because the reduced content of yttrium-stabilized zirconium fine powder deprived the composite of the phase transformation toughening effect of zirconium oxide after sintering, thereby reducing the thermal shock resistance of the refractory.

[0056] As shown in Tables 2-3, compared to Example 1, Comparative Example 3 reduced the tin oxide clinker fine powder content, resulting in a reduction in the number of 18 1100°C water-cooled thermal shock tests for the refractory material, a decrease in glass erosion resistance, and an increase in the erosion rate to 0.35 mm / 24 h. This is because the material system significantly reduces the content of the highly resistant tin oxide. As a result, the small amount of tin oxide cannot form a sufficiently strong spinel with CaO, making it difficult to achieve the purpose of promoting sintering, thereby reducing the erosion resistance and thermal shock resistance.

[0057] As shown in Tables 2-3, compared to Example 3, the addition of excess tin oxide clinker fine powder in Comparative Example 4 reduced the 0.2 MPa refraction temperature to 1520°C, and the number of 1100°C water-cooled thermal shock tests to 20. This is presumably because the excess tin oxide clinker fine powder inhibits the bonding between aluminum oxide and tin oxide, disrupting the internal uniformity of the material and inhibiting sintering. The high bulk density of excess tin oxide leads to the concentration of thermal stress within the material, reducing thermal shock resistance. Furthermore, the excess tin oxide clinker fine powder reacts with some impurities in the material to form low-melting-point compounds, lowering the material's 0.2 MPa refraction temperature.

[0058] As can be seen from Table 2-3, compared with Example 2, the addition of excessive yttrium-stabilized zirconium fine powder in Comparative Example 5 resulted in a higher apparent porosity of 22.3% for the refractory material, and a reduction of the number of 1100°C water-cooled thermal shock tests to 21. This is because the thermal expansion coefficient of zirconium oxide itself is high (the thermal expansion coefficient of zirconium oxide is 10.5×10 -6 / K, the thermal expansion coefficient of corundum is 8.9×10 -6 / K), excessive yttrium-stabilized zirconium fine powder undergoes phase transformation during sintering, which may cause excessive expansion and hinder the movement of Al2O3 grain boundaries, resulting in an increase in the apparent porosity of the material and a reduction in the density and permeability resistance of the refractory material.

[0059] The raw material composition, process conditions and performance test results of the corundum-tin oxide composite refractory materials of Comparative Examples 6-9 are shown in Table 4, wherein the total mass of the remaining raw materials except the water reducer and water is calculated as 100%, and the water reducer and water are calculated as a percentage of the total mass of the remaining raw materials.

[0060] Table 4 Raw material composition, process conditions and performance test results of the corundum-tin oxide composite refractory materials of Comparative Examples 6-9

[0061]

[0062] As shown in Tables 2 and 4, compared to Example 1, Comparative Example 6 uses pure tin oxide fine powder instead of tin oxide clinker fine powder, resulting in a higher apparent porosity of 20.7% for the refractory material. The number of 1100°C water-cooled thermal shock tests is reduced to 18, and the compressive strength is reduced to 93 MPa. This is because the tin oxide clinker fine powder has been treated at high temperatures and is more stable, while pure tin oxide fine powder is highly active and reacts and densifies at lower temperatures. High temperatures can cause overburning, which reduces the material's strength, thereby increasing the apparent porosity and decreasing the thermal stability.

[0063] As can be seen from Tables 2 and 4, compared to Example 1, Comparative Example 7 uses pure tin oxide calcined material instead of tin oxide clinker fine powder, resulting in a refractory material with an apparent porosity as high as 21.5%, a reduction of 20 1100°C water-cooled thermal shock tests, and a reduction of compressive strength to 88 MPa. This is because the pure tin oxide calcined material itself has not been densified and has a low bulk density. The unsintered SnO2 may undergo secondary sintering during subsequent high-temperature use of the composite material, leading to localized volume shrinkage or expansion, resulting in high apparent porosity and reduced strength. Furthermore, the porous tin oxide product formed after firing can exacerbate glass penetration and accelerate erosion. The low-strength porous structure of the product can also cause the material to break and fall off, reducing its thermal shock resistance.

[0064] As shown in Tables 2 and 4, compared to Example 1, Comparative Example 8, which omitted the addition of tin oxide clinker fine powder, resulted in a refractory with an apparent porosity as high as 22.1%, a reduction in the number of 1100°C water-cooled thermal shock tests to 21, a decrease in compressive strength to 82 MPa, and an increase in the glass erosion rate to 0.56 mm / 24 h. This is because the absence of tin oxide makes sintering to densification difficult at high temperatures. Among the main ingredients in the formula, Al₂O₃ and CaO produce calcium hexaaluminate (CA₆) at high temperatures, resulting in an expansion effect that significantly increases apparent porosity and reduces density, leading to a decrease in the refractory's strength and thermal stability. Furthermore, tin oxide clinker fine powder inherently possesses strong corrosion resistance. Without the synergistic protective mechanism of corundum and tin oxide, the matrix lacks the dense, in-situ tin oxide-generated protective layer against glass erosion, reducing its resistance to glass erosion.

[0065] Tables 2 and 4 show that compared to Example 1, Comparative Example 9, which omitted the addition of yttrium-stabilized zirconium fine powder, resulted in a refractory with an apparent porosity of 21%, a reduction in the number of 1100°C water-cooled thermal shock tests to 11, a decrease in compressive strength to 90 MPa, and an increase in the glass erosion rate to 0.22 mm / 24 h. This is primarily due to the absence of yttrium-stabilized zirconium fine powder, which deprives the composite of its phase transformation toughening mechanism, reducing crack propagation resistance and significantly lowering thermal shock resistance. Furthermore, the tin oxide in the matrix cannot form a tin oxide-zirconium oxide solid solution strengthening phase, reducing the bonding strength of the grain boundaries and lowering the refractory's strength.

[0066] In summary, the refractory material prepared by the present invention using a composite of corundum particles of different particle sizes and tin oxide clinker fine powder has good thermal stability under long-term use at high temperatures, does not break or fall off, has good strength and thermal shock resistance, and also has excellent corrosion resistance.

Claims

1. Corundum-tin oxide composite refractory material, characterized in that: The following components are included in percentage by mass, where the total mass of the remaining components except the water reducer is calculated as 100%, and the water reducer is calculated as a percentage of the total mass of the remaining components: 30-35% of corundum particles with a particle size of 0.1mm<≤1mm; 20-25% of the corundum particles with a particle size of 1mm<≤3mm; 15-20% of corundum particles with a particle size of 3mm<≤6mm; Alumina fine powder 5-15%; Tin oxide clinker fine powder 5-15%; Yttrium stabilized zirconium fine powder 3-5%; Calcium aluminate cement fine powder 3-5%; Water reducing agent 0.2-1%; In the tin oxide clinker fine powder, SnO2>98wt.%, Fe2O3<0.2wt.%, Sb2O3<1.5wt.%, CuO<0.6wt.%, and the bulk density is ≥6.6g / cm 3 .

2. The corundum-tin oxide composite refractory material according to claim 1, characterized in that: The corundum particles are sintered corundum or white corundum, Al2O3>99wt.%, Fe2O3<0.2wt.%, and the volume density is>3.5g / cm 3 .

3. The corundum-tin oxide composite refractory material according to claim 1, characterized in that: In the yttrium-stabilized zirconium fine powder, the total content of ZrO2 and HfO2 is greater than 90wt.%, Y2O3 is greater than 8wt.%, Fe2O3 is less than 0.1wt.%, SiO2 is less than 0.3wt.%, and the bulk density is greater than 4.5g / cm 3 .

4. The corundum-tin oxide composite refractory material according to claim 1, wherein In calcium aluminate cement fine powder, Al2O3 72-82wt.%, CaO 18-25wt.%.

5. The corundum-tin oxide composite refractory material according to claim 1, characterized in that: The water reducing agent is one or both of sodium hexametaphosphate and sodium polyacrylate.

6. The corundum-tin oxide composite refractory material according to claim 1, characterized in that: The particle size of the alumina fine powder is less than 44 μm, the particle size of the tin oxide clinker fine powder is less than 88 μm, the particle size of the yttrium stabilized zirconium fine powder is less than 44 μm, and the particle size of the calcium aluminate cement fine powder is less than 44 μm.

7. The method for preparing the corundum-tin oxide composite refractory material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1 mixing: first dry-mix corundum particles, alumina fine powder, tin oxide clinker fine powder, yttrium-stabilized zirconium fine powder and calcium aluminate cement fine powder, then add water reducer and water and mix to obtain mud; S2 vibration molding: inject the clay into the mold and vibrate to form the green body; S3 Drying and Firing: After the formed green body is solidified, it is demoulded, and after natural curing and drying, it is fired to obtain a corundum-tin oxide composite refractory material.

8. The method for preparing the corundum-tin oxide composite refractory material according to claim 7, wherein: In step S1, water accounts for 6-7% of the total mass of the remaining components except the water reducer, the dry mixing time is 3-5 minutes, and the kneading time is 3-5 minutes; in step S2, the vibration molding time is 3-5 minutes.

9. The method for preparing the corundum-tin oxide composite refractory material according to claim 7, wherein: In step S3, the curing time is 2-6 hours, demoulding is performed 18-24 hours after curing, the natural curing time is 3-5 days, the drying temperature is 120-180°C, the drying time is 12-24 hours, the firing temperature is 1450-1550°C, and the insulation time is 12-24 hours.

10. Use of the corundum-tin oxide composite refractory material according to any one of claims 1 to 6, characterized in that: It is used as a refractory material in areas of glass furnaces that come into contact with molten glass.

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