Thermal shock resistant firebrick and method of making same

Abstract

The application relates to the technical field of refractory materials, and discloses a kind of heat shock resistant refractory bricks and a preparation method thereof, the raw materials of the refractory brick include the following components in parts by weight: quartz sand 60-80 parts, mullite powder 40-60 parts, kaolin 20-30 parts, aluminum borate whisker 10-20 parts, mineralizer 2-4 parts; the mineralizer is composed of aluminum boride and sodium oxide. Through the above technical scheme, the problem of poor heat shock resistance of the refractory brick in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to a thermal shock refractory brick and its preparation method. Background Technology

[0002] Refractory bricks, also known as fire bricks, are shaped refractory materials mainly made from refractory clay or other refractory raw materials and are widely used in industries such as metallurgy, glass, cement, and power. With the development of larger blast furnaces, the working environment of refractory bricks has become more severe, with frequent temperature fluctuations, which places higher demands on their thermal shock resistance.

[0003] Currently, most commercially available refractory bricks are andalusite bricks, cordierite-mullite bricks, and high-alumina bricks. These refractory bricks have poor thermal shock resistance and are prone to brick falling off and breaking during use. In severe cases, this can lead to furnace shutdown and major repairs, causing great inconvenience to enterprise production. Therefore, developing a new type of thermal shock resistant refractory brick has significant practical significance and application value. Summary of the Invention

[0004] This invention proposes a thermal shock resistant refractory brick and its preparation method, which solves the problem of poor thermal shock resistance of refractory bricks in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] This invention proposes a thermal shock refractory brick, the raw materials of which include the following components by weight: 60-80 parts of quartz sand, 40-60 parts of mullite powder, 20-30 parts of kaolin, 10-20 parts of aluminum borate whiskers, and 2-4 parts of mineralizer.

[0007] The mineralizing agent consists of aluminum boride and sodium oxide.

[0008] As a further technical solution, the mass ratio of aluminum boride to sodium oxide is 1:7 to 7:1.

[0009] When the mass ratio of aluminum boride to sodium oxide is 1:7 to 7:1, it is beneficial to further improve the thermal shock resistance of refractory bricks.

[0010] As a further technical solution, the mass ratio of aluminum boride to sodium oxide is 5:3.

[0011] When the mass ratio of aluminum boride to sodium oxide is 5:3, the refractory bricks exhibit superior thermal shock resistance.

[0012] As a further technical solution, the aluminum borate whiskers are aluminum borate carbide whiskers.

[0013] Carbonization of aluminum borate whiskers can make the atomic arrangement at the interface of aluminum borate whiskers more compact and reduce interfacial chemical reactions. On the other hand, it can also strengthen aluminum borate whiskers through solid solution treatment, thereby improving the ability of aluminum borate whiskers to resist cracks and further enhancing the thermal shock resistance of refractory bricks.

[0014] As a further technical solution, the method for preparing the aluminum borate carbide whiskers is as follows: a carburizing agent is introduced into the aluminum borate whiskers, and carbonization is performed to obtain the aluminum borate carbide whiskers.

[0015] As a further technical solution, the carburizing agent is one of methane, ethane, and propane.

[0016] As a further technical solution, the flow rate of the carburizing agent is 50~100 sccm.

[0017] As a further technical solution, the carbonization process is carried out at a pressure of 2-4 MPa, a temperature of 800-1000℃, and a time of 4-6 hours.

[0018] As a further technical solution, the particle size of the quartz sand is 0.15~0.2mm;

[0019] The mullite powder has a particle size of 53~74μm;

[0020] The kaolin has a particle size of 15~30μm.

[0021] As a further technical solution, the particle size of the aluminum borate whiskers is 0.3~3μm.

[0022] The present invention also proposes a method for preparing the thermal shock refractory brick, comprising the following steps: mixing the components in the specified weight proportions evenly, adding water and continuing to mix, pressing and molding, drying, and firing to obtain the refractory brick.

[0023] As a further technical solution, the pressure during the pressing process is 80~85MPa.

[0024] As a further technical solution, the drying process is carried out at a temperature of 50~70℃ for 24~36 hours.

[0025] As a further technical solution, the firing temperature is 1200~1300℃ and the time is 10~15h during the firing process.

[0026] The working principle and beneficial effects of this invention are as follows:

[0027] 1. In this invention, the mineralizer is composed of aluminum borate and sodium oxide. The combined use of these two compounds accelerates the conversion of quartz sand into tridymite, thereby forming a network structure in the refractory brick, preventing cracking and improving its thermal shock resistance. Furthermore, the addition of aluminum borate whiskers consumes fracture energy and hinders crack propagation, thus improving the thermal shock resistance of the refractory brick. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specified, in the following examples and comparative examples, the particle size of the quartz sand is 0.2 mm and the silica content is 99 wt%; the particle size of the mullite powder is 65 μm and the silica content is 53 wt%; the particle size of the kaolin is 30 μm and the silica content is 56 wt%; the particle size of the aluminum borate whiskers is 3 μm; the purity of the aluminum boride is 99%; and the purity of the sodium oxide is 99%.

[0030] Example 1

[0031] A method for preparing a thermal shock refractory brick includes the following steps: by weight, 60 parts of quartz sand, 40 parts of mullite powder, 20 parts of kaolin, 10 parts of aluminum borate whiskers, 0.2 parts of aluminum boride and 1.8 parts of sodium oxide are mixed evenly, 10 parts of water are added, mixed evenly, pressed into shape at 80 MPa, dried at 50°C for 36 h, and then fired at 1200°C for 15 h to obtain the refractory brick.

[0032] Example 2

[0033] A method for preparing a thermal shock refractory brick includes the following steps: by weight, 80 parts of quartz sand, 60 parts of mullite powder, 30 parts of kaolin, 20 parts of aluminum borate whiskers, 0.4 parts of aluminum boride and 3.6 parts of sodium oxide are mixed evenly, 15 parts of water are added, the mixture is mixed evenly, pressed into shape at 85 MPa, dried at 70°C for 24 h, and then fired at 1300°C for 10 h to obtain the refractory brick.

[0034] Example 3

[0035] A method for preparing a thermal shock refractory brick includes the following steps: by weight, 80 parts of quartz sand, 60 parts of mullite powder, 30 parts of kaolin, 20 parts of aluminum borate whiskers, 3.6 parts of aluminum boride and 0.4 parts of sodium oxide are mixed evenly, 15 parts of water are added, the mixture is mixed evenly, pressed into shape at 85 MPa, dried at 70°C for 24 h, and then fired at 1300°C for 10 h to obtain the refractory brick.

[0036] Example 4

[0037] A method for preparing a thermal shock refractory brick includes the following steps: by weight, 80 parts of quartz sand, 60 parts of mullite powder, 30 parts of kaolin, 20 parts of aluminum borate whiskers, 0.5 parts of aluminum boride and 3.5 parts of sodium oxide are mixed evenly, 15 parts of water are added, the mixture is mixed evenly, pressed into shape at 85 MPa, dried at 70°C for 24 h, and then fired at 1300°C for 10 h to obtain the refractory brick.

[0038] Example 5

[0039] A method for preparing a thermal shock refractory brick includes the following steps: by weight, 80 parts of quartz sand, 60 parts of mullite powder, 30 parts of kaolin, 20 parts of aluminum borate whiskers, 3.5 parts of aluminum boride and 0.5 parts of sodium oxide are mixed evenly, 15 parts of water are added, the mixture is mixed evenly, pressed into shape at 85 MPa, dried at 70°C for 24 h, and then fired at 1300°C for 10 h to obtain the refractory brick.

[0040] Example 6

[0041] A method for preparing a thermal shock refractory brick includes the following steps: by weight, 80 parts of quartz sand, 60 parts of mullite powder, 30 parts of kaolin, 20 parts of aluminum borate whiskers, 2.5 parts of aluminum boride and 1.5 parts of sodium oxide are mixed evenly, 15 parts of water are added, the mixture is mixed evenly, pressed into shape at 85 MPa, dried at 70°C for 24 h, and then fired at 1300°C for 10 h to obtain the refractory brick.

[0042] Example 7

[0043] The only difference between this embodiment and Embodiment 6 is that, in this embodiment, the aluminum borate whiskers are aluminum borate carbide whiskers;

[0044] The preparation method of aluminum borate whiskers is as follows: place aluminum borate whiskers in a rotary furnace, introduce methane (flow rate of 50 sccm), and carbonize at 2 MPa and 800℃ for 6 h to obtain aluminum borate whiskers.

[0045] Example 8

[0046] The only difference between this embodiment and Embodiment 7 is that, in this embodiment, the preparation method of aluminum borate whiskers is as follows: aluminum borate whiskers are placed in a rotary furnace, methane is introduced (flow rate of 100 sccm), and carbonized at 4 MPa and 1000℃ for 4 hours to obtain aluminum borate whiskers.

[0047] Example 9

[0048] The only difference between this embodiment and Embodiment 8 is that, in this embodiment, the preparation method of aluminum borate whiskers is as follows: aluminum borate whiskers are placed in a rotary furnace, ethane is introduced (the flow rate is 100 sccm), and carbonized at 4 MPa and 1000 °C for 4 hours to obtain aluminum borate whiskers.

[0049] Example 10

[0050] The only difference between this embodiment and Embodiment 8 is that, in this embodiment, the preparation method of aluminum borate whiskers is as follows: aluminum borate whiskers are placed in a rotary furnace, propane is introduced (the flow rate is 100 sccm), and carbonized at 4 MPa and 1000 °C for 4 hours to obtain aluminum borate whiskers.

[0051] Comparative Example 1

[0052] The only difference between this comparative example and Example 1 is that aluminum boride was not added in this comparative example, and the amount of sodium oxide added was 2 parts by weight.

[0053] Comparative Example 2

[0054] The only difference between this comparative example and Example 1 is that sodium oxide was not added in this comparative example, and the weight of aluminum boride added was 2 parts.

[0055] Comparative Example 3

[0056] The only difference between this comparative example and Example 1 is that aluminum boride and sodium oxide were not added in this comparative example.

[0057] Comparative Example 4

[0058] The only difference between this comparative example and Example 1 is that aluminum borate whiskers were not added in this comparative example.

[0059] The following performance tests were performed on the refractory bricks prepared in Examples 1-10 and Comparative Examples 1-4:

[0060] ① Thermal shock resistance: The thermal shock resistance was tested according to GB / T 30873-2014 "Test Method for Thermal Shock Resistance of Refractory Materials", in which the air quenching method was adopted and the test temperature was 1100℃;

[0061] ② Mass loss rate after 30 cycles: The mass loss rate after 30 cycles was tested according to GB / T 30873-2014 "Test Method for Thermal Shock Resistance of Refractory Materials". The air quenching method was used and the test temperature was 1100℃. The formula for calculating the mass loss rate is: Mass loss rate (%) after 30 cycles = (mass of refractory brick before thermal shock test - mass of refractory brick after 30 thermal shock tests) / mass of refractory brick before thermal shock test × 100.

[0062] The test results are shown in Table 1 below.

[0063] Table 1. Test results of thermal shock resistance of refractory bricks

[0064]

[0065] A comparison of Example 1 and Comparative Examples 1-3 shows that the combined use of aluminum boride and sodium oxide in the mineralizer significantly improves the thermal shock resistance of refractory bricks. A comparison of Example 1 and Comparative Example 4 shows that the addition of aluminum borate whiskers helps improve the thermal shock resistance of refractory bricks. A comparison of Examples 2-3 and Examples 4-6 shows that a mass ratio of aluminum boride to sodium oxide of 1:7 to 7:1 is beneficial for further improving the thermal shock resistance of refractory bricks. A comparison of Example 5 and Examples 4 and 6 shows that a mass ratio of aluminum boride to sodium oxide of 5:3 results in refractory bricks with even better thermal shock resistance. A comparison of Example 6 and Examples 7-10 shows that carbonization treatment of aluminum borate whiskers helps to further enhance the thermal shock resistance of refractory bricks.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal shock resistant refractory brick, characterized in that, The raw materials include the following components by weight: 60-80 parts of quartz sand, 40-60 parts of mullite powder, 20-30 parts of kaolin, 10-20 parts of aluminum borate whiskers, and 2-4 parts of mineralizer. The mineralizing agent consists of aluminum boride and sodium oxide.

2. The thermal shock resistant refractory brick according to claim 1, characterized in that, The mass ratio of aluminum boride to sodium oxide is 1:7 to 7:

1.

3. The thermal shock resistant refractory brick according to claim 2, characterized in that, The mass ratio of aluminum boride to sodium oxide is 5:

3.

4. The thermal shock refractory brick according to claim 1, characterized in that, The aluminum borate whiskers are aluminum borate carbide whiskers.

5. The thermal shock resistant refractory brick according to claim 4, characterized in that, The method for preparing the aluminum borate carbide whiskers is as follows: a carburizing agent is introduced into the aluminum borate whiskers, and carbonization is performed to obtain the aluminum borate carbide whiskers.

6. The thermal shock resistant refractory brick according to claim 5, characterized in that, The carburizing agent is one of methane, ethane, and propane.

7. The thermal shock resistant refractory brick according to claim 5, characterized in that, When introducing the carburizing agent, the flow rate is 50~100 sccm.

8. The thermal shock resistant refractory brick according to claim 5, characterized in that, During the carbonization process, the pressure is 2~4MPa, the temperature is 800~1000℃, and the time is 4~6h.

9. The thermal shock resistant refractory brick according to claim 1, characterized in that, The particle size of the quartz sand is 0.15~0.2mm; The mullite powder has a particle size of 53~74μm; The kaolin has a particle size of 15~30μm.

10. A method for preparing thermal shock refractory bricks as described in any one of claims 1 to 9, characterized in that, The process includes the following steps: mixing the components by weight evenly, adding water and continuing to mix, pressing and molding, drying, and firing to obtain refractory bricks.

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