Sandstone high-temperature push plate and preparation method thereof

Abstract

The invention discloses a andalusite high-temperature push plate and a preparation method thereof. The preparation method comprises the following specific steps: mixing the andalusite particles, the fused quartz particles, the andalusite fine powder, the cordierite fine powder, the activated aluminum oxide fine powder, the aluminum-silicon alloy powder and the rare earth composite yttrium-zirconium ceramic powder to obtain a premix; adding the modified aluminum sol into the premix, and stirring to obtain a mixture; carrying out compression molding on the mixture to obtain a green material; and drying and roasting the green body material, and cooling to room temperature to obtain the andalusite high-temperature push plate. Wherein the modified aluminum sol is obtained by uniformly mixing boric acid and aluminum sol. The preparation method is simple in technological process, low in sintering temperature and obvious in energy-saving benefit, the prepared andalusite high-temperature push plate is high in density, low in apparent porosity, high in high-temperature strength, good in thermal shock resistance and high in refractoriness under load, and the service performance of the high-temperature push plate is improved.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, and in particular to a andalusite high-temperature pusher plate and its preparation method. Background Technology

[0002] Andalusite, as an important aluminum-silica natural mineral raw material, is widely used in the field of refractory materials because it can be transformed in situ into mullite under high temperature conditions (Li Yuanyuan, Xu Haijun. Phase transformation and deformation of andalusite, kyanite and sillimanite [J]. Bulletin of Mineralogy, Petrology and Geochemistry, 2023, 42(2): 402~419). In addition to the main components Al2O3 and SiO2, andalusite often contains small amounts of Fe2O3, TiO2, MnO2 and alkali metal oxides (K2O and Na2O) and other impurities.

[0003] Andalusite undergoes an irreversible mullitization transformation at high temperatures, generating in situ mullite crystals with a three-dimensional interwoven network structure and a silica-rich glass phase (Shi Gan, Fan Muxu, Liu Pengcheng, et al. Influence of thermal history on the properties and structure of andalusite-based refractories [J]. Refractory Materials, 2020, 54(5): 423-426). This transformation process endows the material with a series of significant advantages: First, the mullite network can bring extremely high high-temperature strength and excellent creep resistance; second, the moderate volume expansion (about 5-8%) accompanying the transformation can effectively offset some of the shrinkage during the sintering process, thus giving the product excellent high-temperature volume stability; in addition, due to the microstructure of multiple microcracks generated by the expansion, the material has good thermal shock resistance (Wang Tuanshou, Ren Lin, Wu Yongsheng, et al. Research and development trend of andalusite-based refractories [J]. Refractory Materials, 2015, 49(Supplement 1): 78-80+84).

[0004] However, the volume expansion accompanying andalusite during mullification, especially the excessive expansion caused by secondary mullification, has become a challenge in the preparation of andalusite materials and affects the performance of the finished products. Therefore, how to control the mullification behavior of andalusite and improve the volume stability and mechanical properties of the materials has become a key research issue.

[0005] Unlike other bricks and other components, pushers bear the pressure of the material to be fired in the vertical direction during high-temperature service, and are also subjected to continuous horizontal compression from the push rod. Furthermore, pushers are required to remain undeformed and not stick together at high temperatures (otherwise, the pushers will sinter into a whole that is difficult to separate, affecting the stable operation of the high-temperature kiln). This places stringent requirements on the pushers' high-temperature strength, low-melting-point phase, and load softening properties.

[0006] The patented technology "A Andalusite Pusher Plate and its Preparation Method (201310639428.6)" discloses the preparation of andalusite pusher plates using andalusite, white corundum, mullite, alumina micro powder, and kaolin as main raw materials, through processes such as batching, bridging, molding, drying, and high-temperature firing. This process overcomes the defects of pusher plates, such as poor stability and low flexural strength. However, due to the use of kaolin as a raw material, low-melting-point phases are easily generated during high-temperature sintering. This reduces the high-temperature hot strength of the andalusite pusher plate and also easily causes adhesion between pusher plates. Furthermore, the high sintering temperature and long holding time of the pusher plate increase energy consumption and development costs.

[0007] As can be seen from the above, the main problems encountered in the development of andalusite push plates are as follows: (1) Improve the high-temperature hot strength of andalusite pusher plates: andalusite material has obvious advantages. Its phase transformation can form a good bond, which significantly improves the high-temperature hot strength of the material. However, it is not advisable to introduce low-melting-point substances to avoid damaging the high-temperature performance of andalusite pusher plates.

[0008] (2) Promoting the phase transformation and sintering densification of andalusite: The phase transformation of andalusite is accompanied by a certain volume expansion, which is beneficial to the densification of the material by high-temperature sintering. However, excessive volume expansion can easily cause the material to crack and break. Therefore, controlling the transformation rate of andalusite is crucial.

[0009] (3) Reduce the firing temperature of andalusite pusher plate to reduce energy consumption: the firing temperature of andalusite material is relatively high. This is because it is difficult for andalusite to be completely converted into mullite. Usually, methods such as increasing the firing temperature or extending the holding time are used. However, this is contrary to the energy-saving and consumption-reducing requirements of high-temperature industry under the dual carbon background. In addition, the firing of andalusite cannot be carried out by means of low melting point liquid phase sintering (which damages the high-temperature performance of the material). This puts forward higher requirements for the high-temperature sintering method of andalusite material. Summary of the Invention

[0010] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by proposing a high-temperature push plate made of andalusite and its preparation method. This preparation method features a simple process, low sintering temperature, and significant energy-saving benefits. The prepared andalusite high-temperature push plate exhibits high density, low apparent porosity, high high-temperature strength, good thermal shock stability, and high load softening temperature, thereby improving the service performance of the high-temperature push plate.

[0011] The primary objective of this invention is to provide a method for preparing a high-temperature push plate made of andalusite, the specific steps of which are as follows: S1. Mix andalusite particles and fused silica particles at a mass ratio of 100:(10~15) to obtain mixed granular material; S2. Andalusite fine powder, cordierite fine powder, activated alumina fine powder, aluminum-silicon alloy powder and rare earth composite yttrium-zirconium ceramic powder are mixed in a mass ratio of 100:(5~7):(2.0~3.0):(1.5~2.5):(2.8~3.2) to obtain a mixed fine powder. S3. The mixed granular material and the mixed fine powder material are mixed at a mass ratio of 100:(42~55) to obtain a premixed material; S4. Add 4.2~5.5 wt% of modified aluminum sol to the premix and stir to obtain a mixture; S5. Place the mixture in a mold and press it at 120~130MPa for 40~60 seconds to obtain a green blank. S6. After drying the green billet at 80~110℃ for 12~15 hours, it is placed in a high-temperature furnace and heated to 1400~1480℃ at a heating rate of 5~8℃ / min and held at that temperature for 3~5 hours. Then, it is cooled to room temperature at a cooling rate of 3~4℃ / min to obtain the andalusite high-temperature push plate. The modified aluminum sol is prepared by mixing boric acid and aluminum sol at a mass ratio of (0.3~0.4):100, and the solid content of the aluminum sol is 12~15wt%.

[0012] Further, in step S1, the particle size of the andalusite particles is 0.1~0.5mm; the main chemical composition of the andalusite particles is Al2O3 content ≥59wt%, Fe2O3 content ≤0.3wt%, and CaO content ≤0.1wt%.

[0013] Furthermore, in step S1, the particle size of the fused silica particles is 0.3~0.8 mm.

[0014] Furthermore, in step S2, the particle size of the andalusite fine powder is ≤70μm, and the main chemical components of the andalusite fine powder are Al2O3 content ≥59wt%, Fe2O3 content ≤0.3wt%, and CaO content ≤0.1wt%.

[0015] Furthermore, in step S2, the particle size of the cordierite powder is ≤80μm.

[0016] Furthermore, in step S2, the particle size of the activated alumina fine powder is ≤15μm.

[0017] Furthermore, in step S2, the particle size of the aluminum-silicon alloy powder is ≤85μm.

[0018] Further, in step S2, the aluminum-silicon mass ratio of the aluminum-silicon alloy powder is (35~40):100.

[0019] Furthermore, in step S2, the rare earth composite yttrium zirconium ceramic powder is graded YZ-8.8QLD, see GB / T31968-2025.

[0020] The second objective of this invention is to provide a high-temperature push plate made of andalusite prepared by the above-described preparation method.

[0021] The beneficial effects of this invention are: (1) This invention utilizes the low expansion coefficient of fused silica to form composite granules with andalusite. On the one hand, it reduces the thermal expansion of the high-temperature push plate, and on the other hand, it utilizes the absorption of impurity components of andalusite by quartz to achieve crystal stability, thereby further ensuring the high-temperature volume stability of the material.

[0022] (2) The present invention utilizes the high-temperature melting of aluminum-silicon alloy to create a liquid phase environment, which promotes the mullitization of andalusite. At the same time, the in-situ mullitization after alloy oxidation further promotes the crystal growth and development of mullite, and enhances the density and high-temperature strength of the high-temperature push plate.

[0023] (3) This invention utilizes the high-temperature solid solution-desolution and "honeycomb" characteristics of cordierite to absorb structural stress while alleviating the volume expansion caused by the mullitization of high-temperature push plate material components, which is beneficial to improving the thermal shock stability of high-temperature push plates and increasing the cycle service life of push plates.

[0024] (4) The present invention forms a continuous distribution in the matrix by doping and solid solution of components such as yttrium oxide and zirconium oxide. In particular, zirconium oxide absorbs the silicon-rich glass phase produced by the decomposition of andalusite, which significantly improves the mechanical properties of the high-temperature push plate.

[0025] (5) The process of this invention is simple, and the raw material components used do not introduce low melting point phases. While enhancing the transformation of andalusite and its mechanical properties, the sintering temperature and holding time of the material are reduced by the melting of the alloy and the solid solution of the components, so as to achieve energy saving and consumption reduction in material preparation.

[0026] The andalusite high-temperature push plate prepared by this invention was tested and found to have a bulk density of 2.82~2.87 g / cm³. 3 Apparent porosity 11.6~12.3%; compressive strength 177~185MPa; softening temperature under load T 0.6 ≥1760℃; high temperature (1400℃×0.5h) flexural strength 17.2~20.4MPa; residual strength retention rate after three thermal cycles (1100℃×0.5h air quenching) is 91.2~94.6%. Attached Figure Description

[0027] Figure 1 This is the phase diagram of the Mg-Al-Si-O ternary system.

[0028] Figure 2The image shows a SEM image of the andalusite high-temperature push plate prepared in Example 1.

[0029] Figure 3 The image shows the XRD pattern of the andalusite high-temperature push plate prepared in Example 1. Detailed Implementation

[0030] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0031] Example 1 A method for preparing a high-temperature push plate made of andalusite, the specific steps of which are as follows: S1. Mix andalusite particles and fused silica particles in a mass ratio of 100:15 in a mixer for 10-15 minutes to obtain mixed granular material. S2. The fine powders of andalusite, cordierite, activated alumina, aluminum-silicon alloy, and rare earth composite yttrium-zirconium ceramic are mixed in a mass ratio of 100:6:2.0:2.5:2.8 and added to a roller to mix for 35-45 minutes to obtain a mixed fine powder. S3. The mixed granular material and the mixed fine powder material are mixed in a mass ratio of 100:55, and then mixed in a planetary mixer for 20-30 minutes to obtain a premix. S4. Add 5.5 wt% of modified aluminum sol to the premix and stir for 10-15 minutes to obtain a mixture. S5. Place the mixture in a mold and press it at 120MPa for 60 seconds to obtain a green blank. S6. After drying the green billet at 80~110℃ for 12~15 hours, place it in a high-temperature furnace and heat it to 1480℃ at a heating rate of 8℃ / min and hold it at that temperature for 4 hours. Then, cool it to room temperature at a cooling rate of 3℃ / min to obtain the andalusite high-temperature push plate.

[0032] The modified aluminum sol is a mixture of boric acid and aluminum sol at a mass ratio of 0.4:100, with a solid content of 12wt%.

[0033] Figure 2 SEM image of the andalusite high-temperature push plate prepared in Example 1, from... Figure 2 It can be seen that the components of the andalusite high-temperature push plate prepared in this embodiment are evenly dispersed, and the aggregate, fine particles and matrix are tightly filled and connected with no obvious cracks, indicating that the material has a high degree of sintering, good bonding state and high bonding strength.

[0034] Figure 3 The XRD pattern of the andalusite high-temperature push plate prepared in Example 1 is shown below. Figure 3As can be seen, the phase composition of the andalusite high-temperature push plate prepared in this embodiment is mainly corundum phase and mullite phase, and there is no andalusite phase residue, indicating that andalusite has been completely transformed into mullite.

[0035] The andalusite high-temperature push plate prepared in this embodiment was tested and found to have a bulk density of 2.87 g / cm³. 3 Apparent porosity 11.6%; compressive strength 185 MPa; softening temperature under load T 0.6 The temperature was 1770℃; the high temperature (1400℃×0.5h) flexural strength was 20.4MPa; after three thermal cycles (1100℃×0.5h air quenching), the residual strength retention rate reached 91.2%.

[0036] Example 2 A method for preparing a high-temperature push plate made of andalusite, the specific steps of which are as follows: S1. After mixing andalusite particles and fused silica particles at a mass ratio of 100:12, add them to a mixer and mix for 10-15 minutes to obtain mixed granular material. S2. The fine powders of andalusite, cordierite, activated alumina, aluminum-silicon alloy, and rare earth composite yttrium-zirconium ceramic are mixed in a mass ratio of 100:7:2.2:2.0:3.0 and added to a roller to mix for 35-45 minutes to obtain a mixed fine powder. S3. The mixed granular material and the mixed fine powder material are mixed in a mass ratio of 100:50, and then mixed in a planetary mixer for 20-30 minutes to obtain a premix. S4. Add 4.8 wt% of modified aluminum sol to the premix and stir for 10-15 minutes to obtain a mixture. S5. Place the mixture in a mold and press it at 125MPa for 55 seconds to obtain a green blank. S6. After drying the green billet at 80~110℃ for 12~15 hours, place it in a high-temperature furnace and heat it to 1450℃ at a heating rate of 7℃ / min and hold it at that temperature for 5 hours. Then, cool it to room temperature at a cooling rate of 4℃ / min to obtain the andalusite high-temperature push plate.

[0037] The modified aluminum sol is a mixture of boric acid and aluminum sol at a mass ratio of 0.3:100, with a solid content of 13wt%.

[0038] The andalusite high-temperature push plate prepared in this embodiment was tested and found to have a bulk density of 2.86 g / cm³. 3 Apparent porosity 11.9%; compressive strength 181 MPa; softening temperature under load T 0.6The temperature is 1760℃; the high temperature (1400℃×0.5h) flexural strength is 19.3MPa; after three thermal cycles (1100℃×0.5h air quenching), the residual strength retention rate reaches 93.5%.

[0039] Example 3 A method for preparing a high-temperature push plate made of andalusite, the specific steps of which are as follows: S1. Mix andalusite particles and fused silica particles in a mass ratio of 100:10 in a mixer for 10-15 minutes to obtain mixed granular material. S2. The fine powders of andalusite, cordierite, activated alumina, aluminum-silicon alloy, and rare earth composite yttrium-zirconium ceramic are mixed in a mass ratio of 100:5:3.0:1.5:3.2 and added to a roller to mix for 35-45 minutes to obtain a mixed fine powder. S3. The mixed granular material and the mixed fine powder material are mixed in a mass ratio of 100:42, and then mixed in a planetary mixer for 20-30 minutes to obtain a premix. S4. Add 4.2 wt% of modified aluminum sol to the premix and stir for 10-15 minutes to obtain a mixture. S5. Place the mixture in a mold and press it at 130MPa for 40 seconds to obtain a green blank. S6. After drying the green billet at 80~110℃ for 12~15 hours, place it in a high-temperature furnace and heat it to 1400℃ at a heating rate of 5℃ / min and hold it at that temperature for 3 hours. Then, cool it to room temperature at a cooling rate of 4℃ / min to obtain the andalusite high-temperature push plate.

[0040] The modified aluminum sol is a mixture of boric acid and aluminum sol at a mass ratio of 0.3:100, with a solid content of 15wt%.

[0041] The andalusite high-temperature push plate prepared in this embodiment was tested and found to have a bulk density of 2.82 g / cm³. 3 Apparent porosity 12.3%; compressive strength 177 MPa; softening temperature under load T 0.6 The temperature was 1790℃; the high temperature (1400℃×0.5h) flexural strength was 17.2MPa; after three thermal cycles (1100℃×0.5h air quenching), the residual strength retention rate reached 94.6%.

[0042] Comparative Example 1 A method for preparing a high-temperature push plate made of andalusite, the specific steps of which are as follows: S1. After mixing andalusite particles and fused silica particles at a mass ratio of 100:12, add them to a mixer and mix for 10-15 minutes to obtain mixed granular material. S2. The fine powders of andalusite, cordierite, activated alumina, aluminum-silicon alloy, and rare earth composite yttrium-zirconium ceramic are mixed in a mass ratio of 100:7:2.2:3.0:3.0 and added to a roller to mix for 35-45 minutes to obtain a mixed fine powder. S3. The mixed granular material and the mixed fine powder material are mixed in a mass ratio of 100:50, and then mixed in a planetary mixer for 20-30 minutes to obtain a premix. S4. Add 4.8 wt% of modified aluminum sol to the premix and stir for 10-15 minutes to obtain a mixture. S5. Place the mixture in a mold and press it at 125MPa for 55 seconds to obtain a green blank. S6. After drying the green billet at 80~110℃ for 12~15 hours, place it in a high-temperature furnace and heat it to 1450℃ at a heating rate of 7℃ / min and hold it at that temperature for 5 hours. Then, cool it to room temperature at a cooling rate of 4℃ / min to obtain the andalusite high-temperature push plate.

[0043] The modified aluminum sol is a mixture of boric acid and aluminum sol at a mass ratio of 0.3:100, with a solid content of 13wt%.

[0044] The andalusite high-temperature push plate prepared in this comparative example was tested and found to have a bulk density of 2.71 g / cm³. 3 Apparent porosity 14.4%; compressive strength 112 MPa; softening temperature under load T 0.6 The flexural strength was 8.1 MPa at 1610℃; after three thermal cycles (1400℃×0.5h air quenching), the residual strength retention rate reached 81.3%.

[0045] As can be seen, compared with Example 2, increasing the amount of aluminum-silicon alloy powder increases the volume expansion of the metal powder due to oxidation, which reduces the matrix bonding of the material. Furthermore, the content of aluminum-silicon components in the system changes accordingly, further affecting the solid solution-desolution process of cordierite and other components in the system, resulting in a significant reduction in the mechanical properties of the material, such as high-temperature strength.

[0046] For any points not covered above, existing technologies shall apply.

[0047] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature push plate made of andalusite, characterized in that, The specific steps are as follows: S1. Mix andalusite particles and fused silica particles at a mass ratio of 100:(10~15) to obtain mixed granular material; S2. Andalusite fine powder, cordierite fine powder, activated alumina fine powder, aluminum-silicon alloy powder and rare earth composite yttrium-zirconium ceramic powder are mixed in a mass ratio of 100:(5~7):(2.0~3.0):(1.5~2.5):(2.8~3.2) to obtain a mixed fine powder. S3. The mixed granular material and the mixed fine powder material are mixed at a mass ratio of 100:(42~55) to obtain a premixed material; S4. Add 4.2~5.5 wt% of modified aluminum sol to the premix and stir to obtain a mixture; S5. Place the mixture in a mold and press it at 120~130MPa for 40~60 seconds to obtain a green blank. S6. After drying the green billet at 80~110℃ for 12~15 hours, it is placed in a high-temperature furnace and heated to 1400~1480℃ at a heating rate of 5~8℃ / min and held at that temperature for 3~5 hours. Then, it is cooled to room temperature at a cooling rate of 3~4℃ / min to obtain the andalusite high-temperature push plate. The modified aluminum sol is prepared by mixing boric acid and aluminum sol at a mass ratio of (0.3~0.4):100, and the solid content of the aluminum sol is 12~15wt%.

2. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S1, the particle size of the andalusite particles is 0.1~0.5mm; the main chemical composition of the andalusite particles is Al2O3 content ≥59wt%, Fe2O3 content ≤0.3wt%, and CaO content ≤0.1wt%.

3. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S1, the particle size of the fused silica particles is 0.3~0.8 mm.

4. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S2, the particle size of the andalusite fine powder is ≤70μm, and the main chemical components of the andalusite fine powder are Al2O3 content ≥59wt%, Fe2O3 content ≤0.3wt%, and CaO content ≤0.1wt%.

5. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S2, the particle size of the cordierite fine powder is ≤80μm.

6. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S2, the particle size of the activated alumina fine powder is ≤15μm.

7. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S2, the particle size of the aluminum-silicon alloy powder is ≤85μm.

8. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S2, the aluminum-silicon alloy powder has an aluminum-silicon mass ratio of (35~40):

100.

9. The method for preparing a high-temperature push plate made of andalusite as described in claim 1, characterized in that, In step S2, the rare earth composite yttrium zirconium ceramic powder is graded YZ-8.8QLD, see GB / T31968-2025.

10. A high-temperature push plate made of andalusite prepared by the preparation method according to any one of claims 1 to 9.

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