High-strength dense refractory high-chrome brick and its application

Abstract

The application discloses a kind of high-strength dense refractory high-chrome bricks and its application, belong to refractory high-chrome brick technical field, for solving the technical problem that the density, high-temperature resistance and mechanical strength of high-chrome brick in prior art need to be further improved, the application includes the following composition by weight parts: chromium oxide 40-60 parts, bauxite 20-30 parts, quartz sand 5-15 parts, inorganic reinforcing liquid 5-10 parts, auxiliary additive 2-5 parts, polyvinyl alcohol 2-5 parts;The application is reinforced by adding inorganic reinforcing liquid, auxiliary additive and polyvinyl alcohol to high-chrome brick, not only effectively improve the density and thermal shock resistance of high-chrome brick, but also improve its high-temperature performance and strength.

Description

Technical Field

[0001] This invention relates to the field of high-chromium brick technology, specifically to a high-strength, dense, refractory high-chromium brick and its applications. Background Technology

[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 shock, and chemical corrosion, thus requiring very high levels of high-temperature resistance, thermal shock resistance, mechanical strength, and chemical stability.

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

[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 zirconium oxide are usually selected for reinforcement, which can improve the high temperature resistance and mechanical strength to a certain extent.

[0005] However, quartz sand is brittle to a certain extent, and the amount must be strictly controlled. Excessive addition will lead to a decrease in the strength of the brick, especially at high temperatures. Its vitrification may increase the brittleness of the refractory brick and affect the high temperature resistance of the brick.

[0006] Meanwhile, its coefficient of thermal expansion is relatively high. Adding too much will make the coefficient of thermal expansion of high chromium bricks too large, affecting thermal shock performance and mechanical strength. In addition, traditional high chromium brick materials usually use a single auxiliary additive to enhance the properties of high chromium bricks, resulting in the need to further improve the high temperature resistance and density of high chromium bricks. Summary of the Invention

[0007] The purpose of this invention is to provide a high-strength, dense, high-chromium refractory brick and its application, in order to solve the technical problems of high-chromium bricks in the prior art, such as high porosity, poor high-temperature thermal shock resistance, and the need to further improve impermeability and mechanical strength.

[0008] The objective of this invention can be achieved through the following technical solution: 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 additives, and 2-5 parts of polyvinyl alcohol.

[0009] It also includes adding chromium oxide, bauxite, quartz sand, inorganic reinforcing liquid and auxiliary additives to the reactor to obtain a powder mixture;

[0010] Next, polyvinyl alcohol is added and stirred until a uniform slurry is obtained. The slurry is then poured into a mold and shaped using a cold isostatic pressing method. The shaped sample is then pre-sintered at 900-1100℃ for 4 hours to obtain a refractory high-chromium brick blank.

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

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

[0013] Furthermore, the auxiliary additive is composed of rare earth oxides and magnesium oxide in a weight ratio of 2:1, and the rare earth oxides are 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 obtained by the following steps:

[0016] A1. Add nano-silica, nano-zirconia and prepared polyvinyl alcohol to the reaction vessel 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 minutes to obtain the inorganic reinforcing liquid.

[0018] Synthesis mechanism of inorganic reinforcing liquid:

[0019] After adding nano-silica, nano-zirconia, and a prepared polyvinyl alcohol solution to the reactor, ultrasonic dispersion is used to break up the aggregation of nanoparticles through acoustic cavitation effect, thereby improving their dispersibility. Then, the polyvinyl alcohol solution acts as a dispersant, adsorbing onto the surface of the nanoparticles to form a protective layer, preventing particle re-aggregation and thus improving the stability of the suspension. Finally, during vacuum degassing, 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 ratio of the amount of nano-silica, nano-zirconia, and the prepared polyvinyl alcohol solution is 5:5:1, and the concentration of the polyvinyl alcohol solution is 3wt%.

[0021] The present invention also proposes the application of a high-strength, dense, high-chromium refractory brick, which can be used in the iron and steel metallurgy, cement, glass, petrochemical and power industries.

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

[0023] 1. This invention involves adding nano-silica and nano-zirconia to the raw materials, which significantly improves the overall performance of the brick. Due to its high specific surface area and excellent filling properties, nano-silica effectively fills the voids in high-chromium bricks, increasing the brick's density and reducing porosity, thereby enhancing its compressive strength and thermal stability. Furthermore, nano-silica improves the brick's high-temperature resistance, enhancing its stability and service life under extreme high-temperature environments. Nano-zirconia primarily improves the brick's performance by enhancing its high-temperature resistance and thermal shock resistance. Under high-temperature conditions, nano-zirconia maintains high thermal stability, preventing thermal cracking, and effectively alleviates thermal stress caused by temperature changes through its low coefficient of thermal expansion, thus improving the brick's thermal shock resistance and high-temperature flexural strength. More importantly, nano-zirconia also enhances the brick's strength and toughness through a crystal transformation mechanism, improving its impact resistance. The synergistic effect of these two materials effectively improves the density, strength, high-temperature resistance, and thermal shock resistance of high-chromium bricks, significantly enhancing their overall performance under high-temperature conditions.

[0024] 2. This invention involves adding rare earth oxides such as lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide to the raw materials, which can significantly improve the performance of high-chromium bricks. Lanthanum oxide mainly enhances the strength and high-temperature stability of high-chromium bricks by increasing density and improving oxidation resistance. Cerium oxide enhances the stability of high-chromium bricks in extreme high-temperature environments by improving high-temperature resistance and thermal shock resistance. Yttrium oxide helps refine grains, improving the high-temperature strength and thermal shock resistance of high-chromium bricks, especially under drastic temperature changes. Europium oxide further improves thermal shock resistance and enhances the high-temperature stability of the brick by stabilizing the crystal structure. Neodymium oxide refines grains, improves strength and toughness, increases the impact resistance of the brick, and further improves stability at high temperatures. Dysprosium oxide ensures the durability of high-chromium bricks in high-temperature oxidizing environments by enhancing oxidation resistance and high-temperature resistance. The synergistic effect between different oxides significantly improves the overall performance of high-chromium bricks by promoting grain refinement, increasing density, improving thermal shock resistance and high temperature resistance, thus enabling them to exhibit a longer service life in high temperature, high impact and oxidizing environments.

[0025] 3. This invention involves adding polyvinyl alcohol solution to the raw materials twice, which significantly improves the overall performance of the brick. The primary function of the first addition of polyvinyl alcohol solution is to enhance the dispersibility of nano-silica and nano-zirconia. Nanoparticles have a high specific surface area and are prone to aggregation. The polyvinyl alcohol solution, through its surface activity, effectively reduces the attraction between particles, ensuring uniform dispersion of the nanomaterials in the matrix and guaranteeing material homogeneity. This provides a better foundation for the subsequent sintering process. The second addition of polyvinyl alcohol solution aims to improve the density of the high-chromium brick. During sintering, the polyvinyl alcohol solution acts as a binder, promoting particle bonding, filling voids in the brick, reducing porosity, and increasing the bulk density of the brick. This significantly enhances the brick's compressive strength, thermal shock resistance, and high-temperature resistance. Through these two additions, the problem of material inhomogeneity is solved first by improving the dispersibility of nanoparticles, and then the density of the brick is further improved by enhancing the bonding between particles during sintering, thereby strengthening its mechanical properties and thermal stability. The synergistic effect between the two effectively improves the overall performance of high-chromium bricks, making them more adaptable to high temperature, high pressure and complex environments, especially in terms of strength, high temperature resistance and thermal shock resistance. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within 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 CAS number 14808-60-7, model BN-SiO2-002, particle size 30-50nm, and purity 99.99%;

[0028] In this application, the nano-zirconia is selected from Bohuas Nanotechnology (Ningbo) Co., Ltd., CAS No. 64417-98-7, with a particle size of 30-50nm and a purity of 99.9%.

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

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

[0031] Example 1

[0032] This embodiment provides a method for preparing high-strength, dense, high-chromium refractory bricks, including the following steps:

[0033] S1. Preparation of inorganic reinforcing liquid

[0034] Weigh out 10g of nano-silica, 10g of nano-zirconia, and 2g of 3wt% polyvinyl alcohol aqueous solution and add them to the reaction vessel. Disperse the mixture by ultrasonication for 15min. Then place the resulting mixed solution in a vacuum environment and perform vacuum degassing treatment for 10min to obtain the inorganic reinforcing liquid.

[0035] S2, Preparation of powder mixture

[0036] Lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide were mixed evenly in a weight ratio of 6:5:4:1:3:1 to obtain rare earth oxides.

[0037] Rare earth oxides and magnesium oxide are mixed evenly at a weight ratio of 2:1 to obtain auxiliary additives;

[0038] Weigh out 40g of chromium oxide, 20g of bauxite, 5g of quartz sand, 5g of inorganic reinforcing liquid, and 2g of auxiliary additives, and add them to the reaction vessel to obtain a powder mixture.

[0039] S3, refractory high-chromium brick blank

[0040] Weigh 2g of 5wt% polyvinyl alcohol solution and add it to the reaction vessel. Stir until a uniform slurry is obtained, then pour it into a mold and shape it using cold isostatic pressing. Pre-sinter the shaped sample at 900℃ for 4 hours to obtain a refractory high-chromium brick blank.

[0041] S4. Preparation of refractory high-chromium bricks

[0042] The refractory high-chromium brick blanks are then placed in a high-temperature furnace for high-temperature sintering at 1700℃ for 8 hours. After sintering, they are gradually cooled to obtain high-strength, dense refractory high-chromium bricks.

[0043] Example 2

[0044] This embodiment provides a method for preparing high-strength, dense, high-chromium refractory bricks, including the following steps:

[0045] S1. Preparation of inorganic reinforcing liquid

[0046] Weigh out 10g of nano-silica, 10g of nano-zirconia, and 2g of 3wt% polyvinyl alcohol aqueous solution and add them to the reaction vessel. Disperse the mixture by ultrasonication for 23 minutes. Then place the resulting mixed solution in a vacuum environment and perform vacuum degassing treatment for 15 minutes to obtain the inorganic reinforcing liquid.

[0047] S2, Preparation of powder mixture

[0048] Lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide were mixed evenly in a weight ratio of 6:5:4:1:3:1 to obtain rare earth oxides.

[0049] Rare earth oxides and magnesium oxide are mixed evenly at a weight ratio of 2:1 to obtain auxiliary additives;

[0050] Weigh out 50g of chromium oxide, 25g of bauxite, 10g of quartz sand, 8g of inorganic reinforcing liquid, and 8g of auxiliary additives, and add them to the reaction vessel to obtain a powder mixture.

[0051] S3, refractory high-chromium brick blank

[0052] Weigh 3g of 5wt% polyvinyl alcohol solution and add it to the reaction vessel. Stir until a uniform slurry is obtained, then pour it into a mold and shape it using cold isostatic pressing. Pre-sinter the shaped sample at 1000℃ for 4 hours to obtain a refractory high-chromium brick blank.

[0053] S4. Preparation of refractory high-chromium bricks

[0054] The refractory high-chromium brick blanks are then placed in a high-temperature furnace for high-temperature sintering at 1700℃ for 10 hours. After sintering, they are gradually cooled to obtain high-strength, dense refractory high-chromium bricks.

[0055] Example 3

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

[0057] S1. Preparation of inorganic reinforcing liquid

[0058] Weigh out 10g of nano-silica, 10g of nano-zirconia, and 2g of 3wt% polyvinyl alcohol aqueous solution and add them to the reaction vessel. Disperse the mixture by ultrasonication for 30min. Then place the resulting mixed solution in a vacuum environment and perform vacuum degassing treatment for 20min to obtain the inorganic reinforcing liquid.

[0059] S2, Preparation of powder mixture

[0060] Lanthanum oxide, cerium oxide, yttrium oxide, europium oxide, neodymium oxide, and dysprosium oxide were mixed evenly in a weight ratio of 6:5:4:1:3:1 to obtain rare earth oxides.

[0061] Rare earth oxides and magnesium oxide are mixed evenly at a weight ratio of 2:1 to obtain auxiliary additives;

[0062] Weigh out 60g of chromium oxide, 30g of bauxite, 15g of quartz sand, 10g of inorganic reinforcing liquid, and 5g of auxiliary additives, and add them to the reaction vessel to obtain a powder mixture.

[0063] S3, refractory high-chromium brick blank

[0064] Weigh 5g of 5wt% polyvinyl alcohol solution and add it to the reaction vessel. Stir until a uniform slurry is obtained, then pour it into a mold and shape it using cold isostatic pressing. Pre-sinter the shaped sample at 1100℃ for 4 hours to obtain a refractory high-chromium brick blank.

[0065] S4. Preparation of refractory high-chromium bricks

[0066] The refractory high-chromium brick blanks are then placed in a high-temperature furnace for high-temperature sintering at 1800℃ for 12 hours. After sintering, they are gradually cooled to obtain high-strength, dense refractory high-chromium bricks.

[0067] Comparative Example 1

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

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 3 is that the auxiliary additives in step S2 are changed to remove lanthanum oxide, cerium oxide, and yttrium oxide from the rare earth oxides.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 3 is that in step S3, no polyvinyl alcohol solution was added, and the molded sample was directly pre-sintered.

[0073] Performance testing:

[0074] 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 were determined according to the standard GB / T 2997-2015 "Test Methods for Bulk Density, Apparent Porosity and True Porosity of Dense Shaped Refractory Products".

[0075] The thermal shock resistance of high-strength, dense, high-chromium refractory bricks prepared in Examples 1-3 and Comparative Examples 1-3 was determined in accordance with the standard GB / T 3810.9-2016 "Test Methods for Ceramic Tiles - Part 9: Determination of Thermal Shock Resistance" during the cycling process from a high temperature of 1100℃ to a low temperature of 20℃.

[0076] High-strength, dense refractory high-chromium bricks with dimensions of 100×20×20mm were placed in a thermal shock furnace at 1100℃ and held for 20 minutes. After removal, they were placed in cold water to cool for 10 minutes. This process was repeated until the high-chromium bricks broke. The number of times the bricks broke was used as a measure of their thermal shock resistance.

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

[0078] Table 1 - Performance Test Data of Samples

[0079]

[0080] Data Analysis:

[0081] Comparative analysis of the data in Table 1 above shows that the high-strength, dense, high-chromium refractory brick prepared by this invention has an apparent porosity of 11.3% and a bulk density of 3.51 g / cm³. 3 It exhibits thermal shock resistance up to 19 cycles, a high-temperature flexural strength of 46.2 MPa at 1000℃, and a room-temperature flexural strength of 58.2 MPa.

[0082] Compared with the example, Comparative Example 1 showed significantly improved room temperature compressive strength and thermal shock resistance, but had a smaller improvement in apparent porosity, bulk density and high temperature flexural strength, indicating that nano-zirconia can effectively improve the room temperature compressive strength and thermal shock resistance of the brick.

[0083] Compared with the example, Comparative Example 2 showed significantly improved thermal shock resistance and high-temperature flexural strength, but the improvement in apparent porosity, bulk density and room-temperature compressive strength was 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 bricks.

[0084] Compared with the example, Comparative Example 3 showed a significant increase in apparent porosity and a decrease in bulk density, but the improvement in thermal shock resistance, high-temperature flexural strength, and room-temperature compressive strength was relatively small. This indicates that the polyvinyl alcohol solution can effectively improve the dispersibility of raw material particles, prevent particle agglomeration, ensure uniform distribution of particles during the mixing process, enhance the adhesion of the mixture, promote close contact of particles, and thus improve the density of the brick.

[0085] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0086] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0087] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-strength dense refractory high-chrome brick, characterized by, It includes 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 additives and 2-5 parts of polyvinyl alcohol. The auxiliary additive is composed of rare earth oxides and magnesium oxide in a weight ratio of 2:1, and the rare earth oxides are 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. The preparation method of inorganic reinforcing liquid is as follows: nano silica, nano zirconium dioxide and prepared polyvinyl alcohol solution are added to the reaction vessel, ultrasonically dispersed for 15-30 min, and then placed in a vacuum environment for 10-20 min of vacuum degassing treatment to obtain inorganic reinforcing liquid. It also includes adding chromium oxide, bauxite, quartz sand, inorganic reinforcing liquid and auxiliary additives to the reactor to obtain a powder mixture; Next, polyvinyl alcohol is added and stirred until a uniform slurry is obtained. The slurry is then poured into a mold and shaped using a cold isostatic pressing method. The shaped sample is then pre-sintered at 900-1100℃ for 4 hours to obtain a refractory high-chromium brick blank. The refractory high-chromium brick blanks are placed in a high-temperature furnace and sintered at 1700-1800℃ for 8-12 hours. After sintering, they are gradually cooled to obtain high-strength, dense refractory high-chromium bricks.

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

1.

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

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

5. The application of a high-strength, dense, high-chromium refractory brick, characterized in that, The high-strength, dense, refractory high-chromium brick according to any one of claims 1-4 is applied to the iron and steel metallurgy, cement, glass, petrochemical and power industries.

Images