High-strength compact fire-resistant high-chromium brick and application thereof

Abstract

The invention discloses a high-strength compact fire-resistant high-chromium brick and application thereof, belongs to the technical field of fire-resistant high-chromium bricks, and aims to solve the technical problem that the compactness, high temperature resistance, shock resistance and mechanical strength of a high-chromium brick in the prior art need to be further improved. The high-strength and high-wear-resistance composite material is prepared from the following components in parts by weight: 40 to 60 parts of chromium oxide, 20 to 30 parts of bauxite, 5 to 15 parts of quartz sand, 5 to 10 parts of inorganic enhancement liquid, 2 to 5 parts of auxiliary additive and 2 to 5 parts of polyvinyl alcohol, the inorganic reinforcing liquid, the auxiliary additive and the polyvinyl alcohol are added to reinforce the high-chromium brick, so that the compactness and the thermal shock resistance of the high-chromium brick are effectively improved, and the high-temperature resistance and the strength of the high-chromium brick are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-chromium bricks, and particularly to a high-strength dense refractory high-chromium brick and its application. Background Art

[0002] In high-temperature industrial environments, refractory materials, especially refractory bricks, play a crucial role. These materials are often exposed to extreme conditions such as high temperatures, intense thermal shocks, and chemical corrosion. Therefore, they have very high requirements for high-temperature resistance, thermal shock resistance, mechanical strength, and chemical stability.

[0003] As a special refractory material, refractory high-chromium bricks are mainly based on chromium oxide (Cr2O3) and have excellent high-temperature resistance and good thermal shock resistance. They are widely used in high-temperature processes such as metallurgy, chemical engineering, and steel.

[0004] However, in order to improve the high-temperature resistance and mechanical strength of high-chromium bricks in the prior art, other materials such as quartz sand, magnesium oxide, and zirconia are usually selected for modification. Although it can improve the high-temperature resistance and mechanical strength to a certain extent;

[0005] However, quartz sand has a certain brittleness, and the control of the amount needs to be very strict. Excessive addition will lead to a decrease in the strength of the brick body. Especially at high temperatures, its vitrification may increase the brittleness of the refractory brick and affect the high-temperature resistance of the brick body;

[0006] At the same time, its thermal expansion coefficient is relatively high. Excessive addition will make the thermal expansion coefficient of the high-chromium brick too large, affecting the thermal shock performance and mechanical strength. And traditional high-chromium brick materials usually use a single auxiliary additive to modify the high-chromium brick, resulting in the high-temperature resistance and density of the high-chromium brick needing to be further improved. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-strength dense refractory high-chromium brick and its application, which are used to solve the technical problems of high porosity, poor high-temperature resistance and thermal shock resistance, and the need to further improve the anti-permeability and mechanical strength of high-chromium bricks in the prior art.

[0008] The purpose of the present invention can be achieved by the following technical solutions: A high-strength dense refractory high-chromium brick, comprising the following components by weight: 40-60 parts of chromium oxide, 20-30 parts of bauxite, 5-15 parts of quartz sand, 5-10 parts of inorganic reinforcing liquid, 2-5 parts of auxiliary additive, and 2-5 parts of polyvinyl alcohol;

[0009] It also includes adding chromium oxide, bauxite, quartz sand, inorganic reinforcing liquid, and auxiliary additive into a reaction kettle to obtain a powder mixture;

[0010] Then, polyvinyl alcohol is added and stirred until a homogeneous slurry is obtained. After that, it is poured into a mold and shaped by the method of cold isostatic pressing. The formed sample is pre-sintered at 900 - 1100 °C for 4 h to obtain a refractory high-chromium brick blank.

[0011] The refractory high-chromium brick blank is placed in a high-temperature furnace for high-temperature sintering at 1700 - 1800 °C for 8 - 12 h. After sintering is completed, it is gradually cooled to obtain a high-strength dense refractory high-chromium brick.

[0012] Furthermore, the dosage ratio of the chromium oxide, bauxite, quartz sand, inorganic reinforcing liquid, and auxiliary additive is 10:5:2:1:1.

[0013] Furthermore, the auxiliary additive is composed of rare earth oxide and magnesium oxide in a weight ratio of 2:1, and the rare earth oxide is composed of lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide in a weight ratio of 6:5:4:1:3:1.

[0014] Furthermore, the concentration of polyvinyl alcohol is 5 wt%.

[0015] Furthermore, the inorganic reinforcing liquid is prepared by the following steps:

[0016] A1. Add nano-silica, nano-zirconia, and the prepared polyvinyl alcohol into a reaction kettle and ultrasonically disperse for 15 - 30 min to obtain a mixed solution;

[0017] A2. Place the obtained mixed solution in a vacuum environment and perform vacuum degassing treatment for 10 - 20 min to obtain the inorganic reinforcing liquid.

[0018] Synthesis mechanism of the inorganic reinforcing liquid:

[0019] After adding nano-silica, nano-zirconia, and the prepared polyvinyl alcohol solution into the reaction kettle, the ultrasonic dispersion is used to break the aggregation of nano-particles by acoustic cavitation effect to improve their dispersibility; then, the polyvinyl alcohol solution acts as a dispersant to form a protective layer by adsorbing on the surface of nano-particles to prevent particle re-aggregation, thereby improving the stability of the suspension; finally, during the vacuum degassing process, the bubbles and dissolved gases in the solution are removed to ensure that the suspension is uniform and free from bubble interference, thereby obtaining a uniform and stable inorganic reinforcing liquid.

[0020] Furthermore, in step A1, the dosage ratio of the nano-silica, nano-zirconia, and the prepared polyvinyl alcohol solution is 5:5:1, and the concentration of the polyvinyl alcohol solution is 3 wt%.

[0021] The present invention also provides an application of a high-strength dense refractory high-chromium brick, which is applied to the industries of iron and steel metallurgy, cement, glass, petrochemical industry and electric power.

[0022] The present invention has the following beneficial effects:

[0023] 1. By adding nano-silica and nano-zirconia to the raw materials, the overall performance of the brick body can be significantly improved. Due to its high specific surface area and good filling property, nano-silica can effectively fill the voids in the high-chromium brick, improve the densification of the brick body, reduce the porosity, and thus enhance its compressive strength and thermal stability. In addition, nano-silica can also improve the high-temperature resistance of the brick body and enhance its stability and service life in extreme high-temperature environments. Nano-zirconia mainly improves the performance of the brick body by enhancing the high-temperature resistance and thermal shock resistance. Nano-zirconia can maintain high thermal stability under high-temperature conditions, prevent the brick body from generating thermal cracks, and effectively relieve the thermal stress caused by temperature changes through its low coefficient of thermal expansion, thereby improving the thermal shock resistance and high-temperature flexural strength of the brick body. More importantly, nano-zirconia can also enhance the strength and toughness of the brick body through the crystal transformation mechanism and improve its impact resistance. The synergistic effect of the two effectively improves the high-chromium brick in terms of densification, strength, high-temperature resistance and thermal shock resistance, and significantly enhances the comprehensive performance of the brick body under high-temperature conditions.

[0024] 2. By adding rare earth oxides such as lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide and dysprosium oxide to the raw materials, the performance of the high-chromium brick can be significantly improved. Lanthanum oxide mainly enhances the strength and high-temperature stability of the high-chromium brick by improving the densification and antioxidant property; cerium oxide enhances the stability of the high-chromium brick in extreme high-temperature environments by improving the high-temperature resistance and thermal shock resistance; yttrium oxide helps to refine the grains, improve the high-temperature strength and thermal shock resistance of the high-chromium brick, especially showing excellent performance under drastic temperature changes; europium oxide further improves the thermal shock resistance and the high-temperature stability of the brick body by stabilizing the lattice structure; neodymium oxide can refine the grains, improve the strength and toughness, increase the impact resistance of the brick body, and further improve the stability at high temperatures; dysprosium oxide ensures the durability of the high-chromium brick in high-temperature oxidation environments by enhancing the antioxidant property and high-temperature resistance. The synergistic effect between different oxides significantly improves the comprehensive performance of the high-chromium brick by promoting grain refinement, improving densification, enhancing thermal shock resistance and high-temperature resistance, enabling it to exhibit a longer service life in high-temperature, high-impact and oxidation environments.

[0025] 3. In the present invention, the polyvinyl alcohol solution is added to the raw materials twice, which can significantly improve the overall performance of the brick body. The main function of the first addition of the polyvinyl alcohol solution is to enhance the dispersion of nano-silica and nano-zirconia. Nano-particles have a high specific surface area and the characteristic of easy agglomeration. Through its surface activity, the polyvinyl alcohol solution can effectively reduce the attraction between particles, make the nano-materials evenly dispersed in the matrix, ensure the uniformity of the material, and provide a better basis for the subsequent sintering process. The purpose of the second addition of the polyvinyl alcohol solution is to improve the densification of the high-chromium brick. During the sintering process, the polyvinyl alcohol solution acts as a binder, which can promote the bonding between particles, fill the voids in the brick body, reduce the porosity, increase the bulk density of the brick body, and thus significantly enhance the compressive strength, thermal shock resistance and high-temperature resistance of the brick body. Through these two additions, first, the problem of material non-uniformity is solved by improving the dispersion of nano-particles, and then the densification of the brick body is further improved by improving the bonding between particles during the sintering process, enhancing its mechanical properties and thermal stability. The synergistic effect between the two effectively improves the comprehensive performance of the high-chromium brick, making it more adaptable under high temperature, high pressure and complex environments, especially showing more excellent performance in terms of strength, high-temperature resistance and thermal shock resistance. Specific Embodiments

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0027] In this application, the nano-silica is selected from Xi'an Bona Materials Technology Co., Ltd., with a CAS number of 14808-60-7, a model number of BN-SiO2-002, a particle size of 30-50 nm, and a purity of 99.99%;

[0028] In this application, the nano-zirconia is selected from Bohuasi Nano-Technology (Ningbo) Co., Ltd., with a CAS number of 64417-98-7, a particle size of 30-50 nm, and a purity of 99.9%;

[0029] In this application, the chromium oxide is selected from Hebei Good Chemical Co., Ltd., with a CAS number of 1308-38-9, a model number of GN, an execution quality standard of HG / T2775-2010, and a content of 99.5%;

[0030] In this application, the polyvinyl alcohol is selected from Wuhan Xinzhongxin Chemical Technology Co., Ltd., with a CAS number of 9002-89-5, a brand number of 1788, a purity of 99%, a neutral pH value, and a viscosity of 3-70.

[0031] Example 1

[0032] This example provides a method for preparing a high-strength dense refractory high-chromium brick, comprising the following steps:

[0033] S1. Prepare an inorganic reinforcing liquid

[0034] Weigh: 10 g of nano-silica, 10 g of nano-zirconia, and 2 g of 3 wt% polyvinyl alcohol aqueous solution and add them to a reaction kettle. Ultrasonically disperse for 15 min, and then place the obtained mixed solution in a vacuum environment for 10 min of vacuum degassing treatment to obtain an inorganic reinforcing liquid;

[0035] S2. Prepare a powder mixture

[0036] Mix lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide evenly according to a weight ratio of 6:5:4:1:3:1 to obtain rare earth oxides;

[0037] Mix the rare earth oxides and magnesium oxide evenly according to a weight ratio of 2:1 to obtain an auxiliary additive;

[0038] Weigh: 40 g of chromium oxide, 20 g of bauxite, 5 g of quartz sand, 5 g of inorganic reinforcing liquid, and 2 g of auxiliary additive, and add them to a reaction kettle to obtain a powder mixture;

[0039] S3. Refractory high-chromium brick blank

[0040] Weigh: 2 g of 5 wt% polyvinyl alcohol solution and add it to a reaction kettle. Stir until a uniform slurry is obtained, then pour it into a mold and shape it by cold isostatic pressing; pre-sinter the formed sample at 900 °C for 4 h to obtain a refractory high-chromium brick blank;

[0041] S4. Prepare a refractory high-chromium brick

[0042] Then put the refractory high-chromium brick blank into a high-temperature furnace for high-temperature sintering. Sinter at 1700 °C for 8 h. After sintering is completed, gradually cool to obtain a high-strength dense refractory high-chromium brick.

[0043] Example 2

[0044] This example provides a method for preparing a high-strength dense refractory high-chromium brick, comprising the following steps:

[0045] S1. Prepare an inorganic reinforcing liquid

[0046] Weigh: 10 g of nano-silica, 10 g of nano-zirconia, and 2 g of 3 wt% polyvinyl alcohol aqueous solution and add them to a reaction kettle. Ultrasonically disperse for 23 min, and then place the obtained mixed solution in a vacuum environment for 15 min of vacuum degassing treatment to obtain an inorganic reinforcing liquid;

[0047] S2. Prepare the powder mixture

[0048] Mix lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide evenly according to a weight ratio of 6:5:4:1:3:1 to obtain rare earth oxides;

[0049] Mix the rare earth oxides and magnesium oxide evenly according to a weight ratio of 2:1 to obtain an auxiliary additive;

[0050] Weigh: 50 g of chromium oxide, 25 g of bauxite, 10 g of quartz sand, 8 g of inorganic reinforcing liquid, and 8 g of auxiliary additive, and add them to the reaction kettle to obtain a powder mixture;

[0051] S3. Refractory high-chromium brick blank

[0052] Weigh: Add 3 g of a 5 wt% polyvinyl alcohol solution to the reaction kettle, stir until a uniform slurry is obtained, then pour it into a mold and shape it by the method of cold isostatic pressing; pre-sinter the shaped sample at 1000 °C for 4 h to obtain a refractory high-chromium brick blank;

[0053] S4. Prepare refractory high-chromium bricks

[0054] Then put the refractory high-chromium brick blank into a high-temperature furnace for high-temperature sintering at 1700 °C for 10 h. After sintering is completed, gradually cool it to obtain a high-strength dense refractory high-chromium brick.

[0055] Example 3

[0056] This example provides a method for preparing a high-strength dense refractory high-chromium brick, including the following steps:

[0057] S1. Prepare inorganic reinforcing liquid

[0058] Weigh: Add 10 g of nano-silica, 10 g of nano-zirconia, and 2 g of a 3 wt% aqueous polyvinyl alcohol solution to the reaction kettle, ultrasonically disperse for 30 min, and then place the obtained mixed solution in a vacuum environment for 20 min of vacuum degassing treatment to obtain an inorganic reinforcing liquid;

[0059] S2. Prepare the powder mixture

[0060] Mix lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide evenly according to a weight ratio of 6:5:4:1:3:1 to obtain rare earth oxides;

[0061] Mix the rare earth oxides and magnesium oxide evenly according to a weight ratio of 2:1 to obtain an auxiliary additive;

[0062] Weigh: 60 g of chromium oxide, 30 g of bauxite, 15 g of quartz sand, 10 g of inorganic reinforcing liquid, and 5 g of auxiliary additive, and add them to a reaction kettle to obtain a powder mixture;

[0063] S3. Refractory high-chromium brick blank

[0064] Weigh: Add 5 g of 5 wt% polyvinyl alcohol solution to the reaction kettle. After stirring until a uniform slurry is obtained, pour it into a mold and shape it by the method of cold isostatic pressing; pre-sinter the formed sample at 1100 °C for 4 h to obtain a refractory high-chromium brick blank;

[0065] S4. Prepare refractory high-chromium bricks

[0066] Then put the refractory high-chromium brick blank into a high-temperature furnace for high-temperature sintering at 1800 °C for 12 h. After sintering is completed, gradually cool it to obtain a high-strength dense refractory high-chromium brick.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 3 is that in step S1, nano-zirconia was not added.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 3 is that the auxiliary additive in step S2 was changed, and lanthanum oxide, cerium oxide, and yttrium oxide in the rare earth oxide were removed.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 3 is that in step S3, the polyvinyl alcohol solution was not added, and the formed sample was directly pre-sintered.

[0073] Performance test:

[0074] Refer to the standard GB / T 2997-2015 "Experimental Methods for Bulk Density, Apparent Porosity and True Porosity of Dense Shaped Refractory Products" to measure the apparent porosity and bulk density of the high-strength dense refractory high-chromium bricks prepared in Examples 1-3 and Comparative Examples 1-3;

[0075] Refer to the standard GB / T 3810.9-2016 "Test Methods for Ceramic Tiles - Part 9: Determination of Thermal Shock Resistance" to measure the thermal shock resistance of the high-strength dense refractory high-chromium bricks prepared in Examples 1-3 and Comparative Examples 1-3 during the cycle from high temperature of 1100 °C to low temperature of 20 °C;

[0076] Put a high-strength dense refractory high-chromium brick with dimensions of 100×20×20 mm into a thermal shock furnace at 1100 °C, keep it warm for 20 min, then remove it and place it in cold water to cool for 10 min. Repeat this step until the high-chromium brick breaks, and take the number of times at breakage as a measure of the thermal shock resistance;

[0077] Refer to the standard GB / T 3002-2017 "Test Method for High Temperature Flexural Strength of Refractory Materials" to measure the flexural strength of the high-strength dense refractory high-chromium bricks prepared in Examples 1-3 and Comparative Examples 1-3 at room temperature and high temperature (1000 °C). The specific test results are shown in Table 1 below:

[0078] Table 1 - Data Sheet for Performance Detection of Specimens

[0079]

[0080] Data Analysis:

[0081] Comparative analysis of the data in Table 1 above shows that the apparent porosity of a high-strength dense refractory high-chromium brick prepared by the present invention is 11.3%, the bulk density is 3.51 g / cm 3 ³, the thermal shock resistance reaches 19 times, the high temperature flexural strength at 1000 °C reaches 46.2 MPa, and the room temperature flexural strength reaches 58.2 MPa;

[0082] Compared with the example, in Comparative Example 1, its room temperature compressive strength and thermal shock resistance are significantly improved, but the improvement in apparent porosity, bulk density and high temperature flexural strength is relatively small, indicating that nano-zirconia can effectively improve the room temperature compressive strength and thermal shock resistance of the brick body;

[0083] Compared with the example, in Comparative Example 2, its thermal shock resistance and high temperature flexural strength are significantly improved, but the improvement in apparent porosity, bulk density and room temperature compressive strength is relatively small, indicating that lanthanum oxide, cerium oxide and yttrium oxide in rare earth oxides can effectively improve the thermal shock resistance and high temperature flexural strength of the brick body;

[0084] Compared with the example, in Comparative Example 3, its apparent porosity increases significantly, the bulk density decreases, but the improvement in thermal shock resistance, high temperature flexural strength and room temperature compressive strength is relatively small, indicating that the polyvinyl alcohol solution can effectively improve the dispersion of raw material particles, prevent particle agglomeration, ensure uniform distribution of particles during mixing, enhance the adhesiveness of the mixture, promote close contact of particles, and thus improve the denseness of the brick body.

[0085] The above content is only an example and explanation of the structure of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.

[0086] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0087] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific implementation manners. Obviously, according to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A high-strength dense refractory high-chromium brick, characterized in that, It comprises the following components by weight parts: 40 - 60 parts of chromium oxide, 20 - 30 parts of bauxite, 5 - 15 parts of quartz sand, 5 - 10 parts of inorganic reinforcing liquid, 2 - 5 parts of auxiliary additive, and 2 - 5 parts of polyvinyl alcohol; It further comprises adding chromium oxide, bauxite, quartz sand, inorganic reinforcing liquid and auxiliary additive into a reaction kettle to obtain a powder mixture; Then add polyvinyl alcohol, stir until a uniform slurry is obtained, pour it into a mold, and shape it by the method of cold isostatic pressing. Pre-sinter the formed sample at 900 - 1100 °C for 4 h to obtain a refractory high-chromium brick blank; Put the refractory high-chromium brick blank into a high-temperature furnace for high-temperature sintering. Sinter at 1700 - 1800 °C for 8 - 12 h. After sintering is completed, gradually cool it to obtain a high-strength dense refractory high-chromium brick.

2. A high-strength dense refractory high-chromium brick according to claim 1, characterized in that, The dosage ratio of the chromium oxide, bauxite, quartz sand, inorganic reinforcing liquid, and auxiliary additive is 10:5:2:1:

1.

3. A high-strength dense refractory high-chromium brick according to claim 1, characterized in that, The auxiliary additive is composed of rare earth oxide and magnesium oxide in a weight ratio of 2:1, and the rare earth oxide is composed of lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide in a weight ratio of 6:5:4:1:3:

1.

4. A high-strength dense refractory high-chromium brick according to claim 1, characterized in that, The concentration of polyvinyl alcohol is 5 wt%.

5. A high-strength dense refractory high-chromium brick according to claim 1, characterized in that, The inorganic reinforcing liquid is obtained by the following steps: A1. Add nano-silica, nano-zirconia and the prepared polyvinyl alcohol solution into a reaction kettle, and ultrasonically disperse for 15 - 30 min to obtain a mixed solution; A2. Place the obtained mixed solution in a vacuum environment and perform vacuum degassing treatment for 10 - 20 min to obtain the inorganic reinforcing liquid.

6. The high-strength dense refractory high-chromium brick according to claim 5, characterized in that, In step A1, the dosage ratio of the nano-silica, nano-zirconia and the prepared polyvinyl alcohol is 5:5:1, and the concentration of polyvinyl alcohol is 3 wt%.

7. Application of a high-strength dense refractory high-chromium brick, characterized in that, Apply the high-strength dense refractory high-chromium brick according to any one of claims 1 - 6 to the industries of iron and steel metallurgy, cement, glass, petrochemical industry and electric power industry.

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