Thermal shock resistant corundum-mullite multiphase heat storage ceramic material and preparation method thereof

Abstract

The invention provides a thermal shock resistant corundum-mullite multiphase heat storage ceramic material and a preparation method thereof, and belongs to the field of new energy storage materials.The thermal shock resistant corundum-mullite multiphase heat storage ceramic material is prepared from basic powder and an additive Tm2O3 accounting for 5%-10% of the total mass of the basic powder; the basic powder comprises the following components in percentage by mass: 70%-95% of alpha-Al2O3 and 5%-30% of kaolin. The corundum-mullite multiphase heat storage ceramic material prepared by the invention is high in density, high in breaking strength, large in heat storage density and excellent in thermal shock resistance, after 30 times of thermal shock cycle tests at room temperature of 1100 DEG C, the multiphase ceramic does not crack, and the breaking strength of the multiphase ceramic is enhanced; and the preparation process is efficient and convenient, large-scale production is easy to realize, and a new choice is provided for the ultrahigh-temperature heat storage ceramic material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage new materials, and particularly relates to a heat shock resistant corundum-mullite composite heat storage ceramic material and a preparation method thereof. BACKGROUND

[0002] Solar thermal power generation technology is an innovative means of efficiently converting solar radiation energy into electrical energy. Its core principle lies in collecting and focusing sunlight through a collector, converting it into heat energy, and then driving a turbine to generate electricity efficiently. In order to ensure that the system can continue to provide stable power supply at night or in poor lighting conditions, the heat storage device plays a crucial role. This device can store heat energy when sunlight is abundant and release stored heat when light is insufficient, ensuring the continuity of power supply. In the new generation of solar thermal power generation systems, the heat storage material and device need to withstand extreme working conditions, with working temperatures as high as 800℃ or above, and during the heat release process, the temperature can quickly drop to 200℃. Therefore, the heat storage material is required to have extremely high heat storage density to maximize energy storage efficiency, and excellent thermal shock resistance to ensure stable operation under rapid temperature changes. In summary, the heat storage system is undoubtedly a key element in solar thermal power generation technology, and the optimization of its performance is crucial for improving the reliability and efficiency of the entire system.

[0003] Ceramic materials are widely used in the heat storage field of solar thermal power generation technology due to their excellent high-temperature stability, excellent chemical corrosion resistance, high density, and economical cost. Among them, corundum-based ceramics, with their high working temperature, high thermal conductivity, large heat storage density, and good mechanical properties, have become the current mainstream choice of heat storage ceramic materials. However, despite the outstanding performance of corundum-based ceramics in many aspects, their thermal shock resistance has certain limitations, which to some extent limits the further expansion of their application range. For example, Chinese patent "Corundum-mullite ceramic filter plate and its preparation method" (CN119430995A) introduces a corundum-mullite ceramic prepared by using corundum powder, microsilica powder, kyanite, active alumina powder, borax, silica sol, and citric acid. The filtration effect of this material is as high as 85%, but its thermal shock resistance is poor, with only 26 thermal shock times at 750℃ air cooling. Another Chinese patent "Thermal shock resistant and high temperature volume stable ceramic roller and its preparation method" (CN108975923B) introduces a thermal shock resistant and high temperature volume stable corundum-mullite ceramic roller, but its thermal shock resistance test (1100℃-room temperature) is only 20 times without cracking.

[0004] Therefore, it is an urgent need and important challenge in the current field to develop a corundum-based heat storage ceramic material that can exhibit excellent performance in an ultra-high temperature environment (temperature exceeding 1000℃) and at the same time has excellent thermal shock resistance. This will not only greatly improve the overall efficiency and stability of the solar thermal power generation system, but also lay a solid foundation for the continuous progress and development of renewable energy technology. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides an anti-thermal shock corundum-mullite composite heat storage ceramic material and a preparation method thereof, aiming to solve the technical problem of poor thermal shock resistance of existing corundum-based composite ceramics in an ultra-high temperature environment.

[0006] In a first aspect, the present application provides an anti-thermal shock corundum-mullite composite heat storage ceramic material, the preparation raw materials of which include a base powder and an additive Tm2O3 accounting for 5% to 10% of the total mass of the base powder; the base powder includes the following components in terms of mass percentage: α-Al2O3 70% to 95% and kaolin 5% to 30%.

[0007] Preferably, the additive Tm2O3 accounts for 5% of the total mass of the base powder.

[0008] Preferably, the base powder includes the following components in terms of mass percentage: α-Al2O3 75% to 85% and kaolin 15% to 25%.

[0009] In a second aspect, the present application provides a preparation method of an anti-thermal shock corundum-mullite composite heat storage ceramic material, including the following steps: Mixing α-Al2O3, kaolin and the additive, then ball milling and sieving to obtain a mixed powder; granulating and aging the mixed powder, then pressing to obtain a green body; drying the green body and firing at 1440℃ to 1640℃ for 1 to 2 hours to obtain the anti-thermal shock corundum-mullite composite heat storage ceramic material.

[0010] Preferably, the mixed powder is a 250 mesh undersize product.

[0011] Preferably, the granulation process specifically involves adding 8wt% to 15wt% of water to the mixed powder for spray granulation.

[0012] Preferably, the aging process specifically involves aging at 25 to 30℃ for 24 to 48 hours.

[0013] Preferably, the pressing conditions are: a molding pressure of 30 to 50kN and a pressure holding time of 30 to 60s.

[0014] Preferably, the drying temperature is 80℃ to 90℃ and the drying time is 24 to 36 hours.

[0015] Preferably, the heating rate of the sintering is 3-8℃ / min.

[0016] Compared with the prior art, the application has the beneficial effects that: The corundum-mullite composite heat storage ceramic material prepared by taking Tm2O3 as an additive has high density, high bending strength, high heat storage density and excellent thermal shock resistance. After 30 thermal shock cycles between room temperature and 1100 DEG C, the composite ceramic does not crack, and the bending strength is enhanced. The mullite and di-mytal disilicate separated out during the thermal shock not only enhance the tightness of the grain-to-grain combination, but also further refine the grains, effectively relieve the thermal stress concentration in the sample, thereby significantly reducing the crack initiation and propagation, and improving the thermal shock resistance of the sample.

[0017] In addition, the preparation process of the application is simple and efficient, convenient to operate, easy to realize large-scale production, provides strong support for mechanized and automated production, and provides a new choice for ultra-high temperature heat storage ceramic materials, and has good application prospect in many fields such as new generation of tower type solar thermal power generation and waste heat power generation. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The XRD graph of the thermal shock resistant corundum-mullite composite heat storage ceramic material prepared in Example 1 of the application; Figure 2 The SEM graph of the cross section of the thermal shock resistant corundum-mullite composite heat storage ceramic material prepared in Example 1 of the application; Figure 3 The SEM graph of the cross section of the thermal shock resistant corundum-mullite composite heat storage ceramic material prepared in Example 1 of the application after 30 thermal shocks; Figure 4 The XRD graph of the thermal shock resistant corundum-mullite composite heat storage ceramic material prepared in Comparative Example 3 of the application. DETAILED DESCRIPTION

[0019] The embodiments of the technical scheme of the application will be described in detail below with reference to the drawings. The following examples are only used to more clearly illustrate the technical scheme of the application, and therefore only serve as examples, and cannot limit the protection scope of the application.

[0020] In order to solve the technical problem of poor thermal shock resistance of existing corundum-based composite ceramics in an ultrahigh temperature environment, the application provides a kind of thermal shock resistant corundum-mullite composite heat storage ceramic material and a preparation method thereof, wherein by introducing an additive Tm2O3, the mullite and dimyristic acid precipitated during thermal shock not only enhances the tightness of grain boundary bonding, but also further refines the grain, effectively relieves the phenomenon of thermal stress concentration in the material, and further significantly reduces the initiation and propagation of cracks, and improves the thermal shock resistance of the material.

[0021] In the first aspect, the application provides a kind of thermal shock resistant corundum-mullite composite heat storage ceramic material, and the preparation raw material includes base powder and 5%~10% of additive Tm2O3 in total mass of base powder;The base powder includes the following components by mass percentage: alpha-Al2O3 70%~95% and kaolin 5%~30%.

[0022] In the technical scheme of the embodiment of the application, the Tm2O3 added in the heat storage ceramic material during sintering generates a low viscosity Tm2O3-Al2O3-SiO2 liquid phase with Al2O3 and SiO2, effectively controls the precipitation process of mullite phase, and reduces the volume expansion phenomenon caused by mullite crystallization. The precipitation of dimyristic acid effectively inhibits the abnormal growth of corundum grains, enhances the tightness of grain boundary bonding, optimizes the overall microstructure, effectively relieves the phenomenon of thermal stress concentration in the heat storage ceramic material, and further significantly reduces the initiation and propagation of cracks, and improves the thermal shock resistance of the heat storage ceramic material.

[0023] Further, in some embodiments, the additive Tm2O3 accounts for 5% of the total mass of the base powder.

[0024] In the technical scheme of the embodiment of the present application, the corundum-mullite composite heat storage ceramic material obtained by adding 5% of the additive Tm2O3 has the optimal thermal shock resistance, because the Tm2O3-Al2O3-SiO2 liquid phase generated by the reaction between Tm2O3 and the components in the base powder at the proportion can better control the precipitation of the mullite phase, which not only ensures the reasonable generation of the mullite phase to enhance the material performance, but also maximally reduces the negative influence of the volume expansion. Meanwhile, the appropriate amount of di-mendipine is precipitated and “pinned” at the corundum grain boundary, and the inhibition effect on the abnormal growth of the corundum grain is optimal, so that the grain size distribution is more uniform, the grain-to-grain bonding is more compact, the microstructure of the material is further optimized, the internal thermal stress concentration of the sample is effectively relieved, and then the crack initiation and propagation are significantly reduced, thereby the thermal shock resistance of the material is significantly improved. When the addition amount of Tm2O3 is too high, although the content of di-mendipine increases, the formation of mullite is also seriously hindered, which leads to the excessive proportion of the glass phase in the sample. At this time, the compactness of the grain-to-grain bonding in the sample is reduced. This change adversely affects the bending strength of the sample.

[0025] Further, in some embodiments, the base powder includes the following components in terms of mass percentage: 75% to 85% of α-Al2O3 and 15% to 25% of kaolin.

[0026] In the technical scheme of the embodiment of the present application, the introduction of appropriate kaolin makes the sample produce an appropriate amount of liquid phase during the sintering process, thereby accelerating the mass transfer speed and promoting the generation of mullite. The mullite grains are “pinned” in the gap of the corundum grains, effectively hindering the further growth of the corundum grains, thereby reducing the number of pores in the material, making the overall structure more compact, and further improving the bending strength and density of the sample. Too little kaolin has no significant effect on the enhancement of the corundum-based ceramic; too much kaolin will lead to the formation of a large amount of glass phase, causing the microcracks to expand along the grain boundary, thereby reducing the bending strength of the sample. Meanwhile, too much glass phase is prone to generate a large number of microcracks during the thermal shock cycle, further accelerating the crack propagation speed, thereby seriously damaging the thermal shock resistance of the sample.

[0027] In a second aspect, the embodiment of the present application provides a preparation method of a thermal shock resistant corundum-mullite composite heat storage ceramic material, including the following steps: The α-Al2O3, kaolin and additive are mixed and then ball milled to obtain a mixed powder; the mixed powder is granulated and aged, and then pressed to obtain a green body; the green body is dried and then sintered at 1440 ℃ to 1640 ℃ for 1 to 2 hours to obtain the thermal shock resistant corundum-mullite composite heat storage ceramic material.

[0028] In the technical scheme of the embodiment of the application, the ball milling process can make the raw materials fully mixed and uniform, refine the particle size, and increase the contact area between the raw materials, thereby laying a foundation for subsequent reaction and performance improvement; the granulation process makes the powder have good fluidity and formability, facilitating the pressing forming operation; the aging process further improves the plasticity and uniformity of the powder and improves the quality of the green body; an ideal complex structure is formed in the sintering process, which endows the material with excellent performance; the addition of rare earth oxides promotes the sintering of the ceramic material, and as the content of the rare earth oxides increases, the sintering temperature can be appropriately reduced.

[0029] Further, in some embodiments, the mixed powder is 250 mesh undersize.

[0030] In the technical scheme of the embodiment of the application, the particle size of 250 mesh undersize ensures sufficient reaction of the raw materials and is beneficial to the forming and sintering.

[0031] Further, in some embodiments, the granulation process specifically comprises: adding 8wt%-15wt% water to the mixed powder for spray granulation.

[0032] In the technical scheme of the embodiment of the application, the appropriate water content can make the granulation effect best, ensuring the fluidity and formability of the powder.

[0033] Further, in some embodiments, the aging process specifically comprises: aging at 25-30℃ for 24-48h.

[0034] Further, in some embodiments, the conditions for the pressing forming are: the forming pressure is 30-50kN, and the pressure holding time is 30-60s.

[0035] In the technical scheme of the embodiment of the application, the appropriate pressure and time can ensure that the green body has sufficient strength and density.

[0036] Further, in some embodiments, the drying temperature is 80℃-90℃, and the drying time is 24h-36h.

[0037] Further, in some embodiments, the sintering temperature rising rate is 3-8℃ / min.

[0038] In the technical scheme of the embodiment of the application, the appropriate temperature rising rate is helpful to the uniform change of the internal structure of the material, ensuring the stability of the material performance.

[0039] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product specifications were used. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased commercially.

[0040] In the following examples and comparative examples of the present invention, α-Al2O3 was purchased from China Aluminum Shandong Co., Ltd., and its composition is (mass percentage): SiO2 0.06%, Al2O3 99.20%, Fe2O3 0.01%, CaO 0.06%, K2O 0.01%, Na2O 0.44%, and the balance is loss on ignition.

[0041] Kaolin was purchased from China Kaolin Co., Ltd., and its composition is (mass percentage): SiO2 44.08%, Al2O3 37.49%, Fe2O3 0.43%, CaO 0.07%, MgO: 0.38%, K2O 1.80% and the balance loss on ignition.

[0042] Example 1 A method for preparing a thermal shock resistant corundum-mullite composite heat storage ceramic material comprises the following steps: (1) Raw material processing: 78.84% α-Al2O3 and 21.16% kaolin are taken in mass percentage, totaling 100wt%, to form a basic powder, and Tm2O3 accounting for 5% of the mass of the basic powder is added, and the mixture is placed in a ball mill for mixing. After ball milling, the mixture is passed through a 250-mesh sieve, and the sieve residue is taken to obtain a uniformly mixed powder; (2) Granulation: 10 wt% water was added to the mixed powder by spray drying to perform granulation; (3) Aging: Store the granulated raw materials in sealed containers and age them at 25°C for 24 hours; (4) Molding: After aging, the raw materials were weighed and poured into a mold for pressing. The molding pressure was 40 kN and the holding time was 60 s to obtain a green body. (5) Drying: Place the green body in a constant temperature drying oven (90°C) and dry for 24 hours; (6) Firing: Place the dried green body in a high-temperature electric furnace, heat it to 1520°C at a rate of 5°C / min, and then keep it warm and sinter it for 2 hours to obtain a thermal shock-resistant corundum-mullite composite heat storage ceramic material.

[0043] Example 2 A method for preparing a thermal shock resistant corundum-mullite composite heat storage ceramic material comprises the following steps: (1) Raw material treatment: take 78.84% of α-Al2O3 and 21.16% of kaolin according to the mass percentage, total 100wt%, form a base powder, plus 7% of Tm2O3 in the mass of the base powder, place in a ball mill for mixing, sieve the undersize after ball milling through a 250 mesh sieve, and obtain a uniformly mixed powder; (2) Granulation: add 12wt% of water to the mixed powder by spray drying method for granulation; (3) Aging: seal the granulated raw material in a container for storage, and age at 25℃ for 24h; (4) Molding: after aging, weigh the raw material, pour it into a mold for compression molding, the molding pressure is 40kN, and the pressure holding time is 60s, to obtain a green body; (5) Drying: place the green body in a constant temperature drying oven (90℃) for drying for 24h; (6) Sintering: place the dried body in a high temperature electric furnace, heat to 1480℃ at a rate of 5℃ / min, and then sinter for 2h, to obtain a thermal storage ceramic material of thermal shock resistant corundum-mullite composite phase.

[0044] Example 3 A preparation method of a thermal shock resistant corundum-mullite composite phase thermal storage ceramic material, specifically comprising the following steps: (1) Raw material treatment: take 78.84% of α-Al2O3 and 21.16% of kaolin according to the mass percentage, total 100wt%, form a base powder, plus 9% of Tm2O3 in the mass of the base powder, place in a ball mill for mixing, sieve the undersize after ball milling through a 250 mesh sieve, and obtain a uniformly mixed powder; (2) Granulation: add 15wt% of water to the mixed powder by spray drying method for granulation; (3) Aging: seal the granulated raw material in a container for storage, and age at 25℃ for 24h; (4) Molding: after aging, weigh the raw material, pour it into a mold for compression molding, the molding pressure is 40kN, and the pressure holding time is 60s, to obtain a green body; (5) Drying: place the green body in a constant temperature drying oven (90℃) for drying for 24h; (6) Sintering: place the dried body in a high temperature electric furnace, heat to 1460℃ at a rate of 5℃ / min, and then sinter for 2h, to obtain a thermal shock resistant corundum-mullite composite phase thermal storage ceramic material.

[0045] Comparative Example 1 The difference between the present comparative example and Example 1 is that the additive in step (1) is replaced by Tm2O3 with cordierite; step (1) is specifically as follows: taking 78.84% α-Al2O3, 21.16% kaolin clay, accounting for 100wt%, to form a basic powder, adding 20% cordierite of the mass of the basic powder, and placing in a ball mill to mix, to obtain a mixed powder with uniform mixing; other steps and conditions are the same as those in Example 1.

[0046] Comparative Example 2 The difference between the present comparative example and Example 1 is that the additive in step (1) is replaced by Tm2O3 with andalusite; step (1) is specifically as follows: taking 78.84% α-Al2O3, 21.16% kaolin clay, accounting for 100wt%, to form a basic powder, adding 20% andalusite of the mass of the basic powder, and placing in a ball mill to mix, to obtain a mixed powder with uniform mixing; the sintering temperature in step (6) is 1640℃; other steps and conditions are the same as those in Example 1.

[0047] Comparative Example 3 The difference between the present comparative example and Example 1 is that the additive in step (1) is replaced by Tm2O3 with Y2O3; step (1) is specifically as follows: taking 78.84% α-Al2O3, 21.16% kaolin clay, accounting for 100wt%, to form a basic powder, adding 5% Y2O3 of the mass of the basic powder, and placing in a ball mill to mix, to obtain a mixed powder with uniform mixing; the sintering temperature in step (6) is 1440℃; other steps and conditions are the same as those in Example 1.

[0048] Comparative Example 4 The difference between the present comparative example and Example 1 is that the additive in step (1) is replaced by Tm2O3 / Y2O3 composite; step (1) is specifically as follows: taking 78.84% α-Al2O3, 21.16% kaolin clay, accounting for 100wt%, to form a basic powder, adding 2.5% Tm2O3 and 2.5% Y2O3 of the mass of the basic powder, and placing in a ball mill to mix, to obtain a mixed powder with uniform mixing; other steps and conditions are the same as those in Example 1.

[0049] Comparative Example 5 The difference between the present comparative example and Example 1 is that the additive in step (1) is 3% Tm2O3; the preparation method of the corundum-mullite composite heat storage ceramic material specifically comprises the following steps: (1) Raw material treatment: take 78.84% of α-Al2O3 and 21.16% of kaolin, accounting for 100wt%, form a base powder, plus 3% of Tm2O3 of the mass of the base powder, put it in a ball mill, sieve the undersize after ball milling, and get a mixed powder with uniform mixing; (2) Granulation: add 8wt% of water to the mixed powder by spray drying method for granulation; (3) Aging: store the granulated raw material in a container, and store it at 25°C for 24h; (4) Forming: after aging, weigh the raw material and pour it into a mold for pressing forming, the forming pressure is 40kN, and the holding time is 60s to obtain a green body; (5) Drying: dry the green body in a constant temperature drying oven (90°C) for 24h; (6) Sintering: place the dried body in a high temperature electric furnace, heat to 1540°C at a rate of 5°C / min, and then sinter for 2h to obtain a corundum-mullite composite heat storage ceramic material.

[0050] Performance test The heat storage ceramic materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested for performance, and the specific test methods were as follows: (1) The bending strength test method is: according to the national standard GB / T6569-2006, the bending strength of the heat storage ceramic material is measured by three-point bending method. In the test process, the maximum load at the time of sample fracture is recorded, and the size parameters of the sample are combined to calculate the bending strength of the heat storage ceramic material by formula 1.

[0051] Formula 1: .

[0052] In the formula, σ b bending strength (MPa); P—load at fracture (N); B—width of cross section (mm); H—height of cross section (mm); L—span between two supports (mm); K—lever arm ratio of equipment (K=1 in this experiment).

[0053] (2) The porosity test method is: based on the vacuum method specified in the national standard GB / T25995-2010, the Archimedes principle (Archimedes drainage method) is used to test the porosity of the sample. With the aid of AUY120 electronic balance (precision of 0.1 mg) produced by Shimadzu Company, and combined with formula 2 to calculate the porosity.

[0054] Formula 2: .

[0055] M1—mass of the dry sample (g); M2—mass of the sample in water (g); M3—mass of the sample after adsorbing saturated water (g).

[0056] (3) The heat storage density test method is that the specific heat capacity of the ceramic sample is tested by using a microcalorimeter (model C80) produced by the French Setaram Company. The temperature range for testing is room temperature~1000℃. In order to further explore the heat storage capacity of the ceramic material, based on the measured specific heat capacity data, the heat storage density of the ceramic sample is further calculated by using formula 3.

[0057] Formula 3: .

[0058] In the formula, Q—heat storage density (kJ·kg -1 ); C—specific heat capacity (J·(g·K) -1 ); T0—initial temperature at the time of testing (room temperature, K); T1—maximum temperature at the time of testing (K).

[0059] (4) The thermal shock resistance test method is that the thermal shock experiment is performed on the ceramic sample in a box-type energy-saving electric resistance furnace (model SX2-5-12), and the thermal shock resistance of the ceramic sample is characterized according to the strength loss rate. The thermal shock experiment process is as follows: 1, the box-type electric resistance furnace is heated to a preset 1100℃ at a speed of 5℃·min -1 ; 2, the sintered ceramic sample is placed in the box-type electric resistance furnace, and kept in a constant temperature state for 15 min; 3, after 15 min, the sample is quickly taken out from the box-type electric resistance furnace, and then immediately cooled to room temperature by air cooling. This series of operations constitutes a complete thermal shock cycle process. In order to comprehensively investigate the thermal shock resistance of the ceramic sample, the above thermal shock cycle steps 2 and 3 are repeated until the preset maximum thermal shock number (30 times) is reached. After the experiment is completed, the three-point bending method is used to measure the bending strength performance of the sample after different thermal shock cycle numbers by using a universal testing machine. Then, the strength loss rate of the sample is calculated by using formula 4, so as to scientifically and objectively judge the advantages and disadvantages of the thermal shock resistance.

[0060] Formula 4: .

[0061] In the formula, S a —strength loss rate of the sample (%); σ0—strength of the sample before thermal shock (MPa); σ a —strength of the sample after thermal shock (MPa).

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

[0063] Table 1

[0064] As can be seen from the results of Table 1, the corundum-mullite composite heat storage ceramic materials prepared in Examples 1-3 have good thermal shock resistance, and after 30 thermal shock cycles between room temperature and 1100℃, the composite ceramics do not show cracking phenomenon, and the bending strength is enhanced, and the performance of Example 1 is the best.

[0065] Figure 1 The XRD pattern of the corundum-mullite composite heat storage ceramic material prepared in Example 1 is shown in Figure 1, and the heat storage ceramic material is composed of corundum, mullite and dimyristic acid. Figure 1 The additional Tm2O3 generates a lower viscosity Tm2O3-Al2O3-SiO2 liquid phase with Al2O3 and SiO2, effectively controls the precipitation process of the mullite phase, and reduces the volume expansion phenomenon caused by mullite crystallization. Figure 2 The SEM image of the cross section of the corundum-mullite composite heat storage ceramic material prepared in Example 1 is shown in Figure 2. Figure 3 The SEM image of the cross section of the corundum-mullite composite heat storage ceramic (Example 1) after 30 thermal shock cycles is shown in Figure 3. Figure 2 and Figure 3 As shown in Figures 3 and 4, the precipitation of dimyristic acid effectively inhibits the abnormal growth of corundum grains, enhances the tightness of grain boundary bonding, optimizes the overall microstructure, effectively relieves the thermal stress concentration phenomenon in the sample, and thus significantly reduces the initiation and propagation of cracks, and improves the thermal shock resistance of the sample.

[0066] The data of Comparative Example 1 shows that the introduction of cordierite improves the thermal shock resistance of the sample to some extent, but the bending strength is far less than that of the sample prepared in Example 1. The data of Comparative Example 2 shows that the introduction of andalusite not only reduces the sintering performance of the ceramic sample, but also damages the thermal shock resistance of the sample. This is because cordierite and andalusite will decompose at high temperature, and the introduction of cordierite and andalusite cannot effectively improve the strength and thermal shock resistance of the corundum-mullite composite heat storage ceramic.

[0067] The data of Comparative Example 3 shows that the introduction of Y2O3 reduces the sintering temperature of the sample, but is not conducive to improving the thermal shock resistance. Generally, with the increase of the electric field strength of rare earth cations, the ability to provide O 2- will be weaker, resulting in an increase in the viscosity of the liquid phase. According to the calculation formula of electric field strength CFS=v / r² (where v is the ion valence and r is the ion radius), the ion radius of Y 3+ (0.900 Å) is larger than that of Tm 3+The ionic radius of Y3+is 0.869 Å, and thus the viscosity of the generated Y2O3-Al2O3-SiO2 liquid phase is lower, and the sintering performance of the sample is significantly improved. However, for the Al2O3-rich and SiO2-poor system, the liquid phase seriously inhibits the generation of mullite, resulting in a large proportion of corundum in the sample. On the one hand, the abnormal growth of the extracted yttrium disilicate to corundum grains is limited, and on the other hand, the improvement of the thermal shock resistance of mullite to the sample is limited. Figure 4 The XRD pattern of the heat storage ceramic material prepared in Comparative Example 3 is shown in FIG. 3. Figure 4 The XRD pattern of the heat storage ceramic material prepared in Comparative Example 3 is shown in FIG. 3.

[0068] The data of Comparative Example 4 show that the introduction of the composite additive improves the bending strength and density of the sample, but the thermal shock resistance is not as good as that of the sample prepared in Example 1. Therefore, the improvement effect of the introduction of the Tm2O3 / Y2O3 composite additive on the thermal shock resistance of the corundum-mullite composite heat storage ceramic is weaker than that of the single Tm2O3 additive.

[0069] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other ways constructed by combining part of the components of the embodiments are also included in the scope of the present application.

Claims

1. A thermal shock resistant corundum-mullite composite heat storage ceramic material, characterized in that: The raw materials for preparation include basic powder and an additive Tm2O3 accounting for 5% to 10% of the total mass of the basic powder; the basic powder includes the following components by mass percentage: 70% to 95% of α-Al2O3 and 5% to 30% of kaolin.

2. The thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 1, characterized in that: The additive Tm2O3 accounts for 5% of the total mass of the basic powder.

3. The thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 1, characterized in that: The basic powder comprises the following components by mass percentage: 75% to 85% of α-Al2O3 and 15% to 25% of kaolin.

4. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to any one of claims 1 to 3, wherein: The following steps are involved: α-Al2O3, kaolin and an additive are mixed, ball-milled and sieved to obtain a mixed powder; the mixed powder is granulated and aged, and then pressed into a green body; the green body is dried and sintered at 1440°C to 1640°C for 1 to 2 hours to obtain the thermal shock-resistant corundum-mullite composite heat storage ceramic material.

5. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 4, characterized in that: The mixed powder is a material under a 250-mesh sieve.

6. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 4, characterized in that: The granulation process specifically includes: adding 8wt% to 15wt% of water to the mixed powder to perform spray granulation.

7. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 4, characterized in that: The aging treatment specifically includes aging at 25-30°C for 24-48 hours.

8. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 4, characterized in that: The compression molding conditions are: a molding pressure of 30-50 kN and a holding time of 30-60 s.

9. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 4, characterized in that: The drying temperature is 80° C. to 90° C., and the drying time is 24 hours to 36 hours.

10. The method for preparing the thermal shock resistant corundum-mullite composite heat storage ceramic material according to claim 4, characterized in that: The heating rate of the sintering is 3-8°C / min.

Images