A yttria-corundum-mullite composite

Abstract

The application discloses a yttria-corundum-mullite composite material, which comprises the following chemical components in percentage by mass: mullite 34.3%-34.475%, corundum 63.7%-64.025% and yttria 1.5%-2%; the apparent porosity of the composite material is 17.13%-18.03%; the composite material comprises corundum phase, mullite phase and yttrium aluminum garnet phase, and the yttrium aluminum garnet phase is generated by solid phase reaction of yttria and corundum in a high-temperature sintering process; by adding 1.5%-2wt% yttria as a modifier, the bending strength of the composite material is up to 58.53MPa, and the strength is improved by 131.50% compared with that of the corundum-mullite material without adding yttria; the apparent porosity is reduced to 17.13%-18.03%, the bulk density is optimized to 2.4333g / cm3, and the densification degree is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of composite materials for sintering and solidifying fly ash from waste melting furnaces, specifically to a yttrium oxide-corundum-mullite composite material, its preparation method, and its application. Background Technology

[0002] Sintering and solidification of fly ash from waste melting furnaces is a core technology for achieving harmless and resource-based treatment of fly ash. It requires stable operation under harsh conditions of high temperature (1200-1300℃) and corrosion by chloride salts and heavy metals. The performance of the carrier crucible directly determines the sintering effect and equipment lifespan.

[0003] Corundum (Al₂O₃) and mullite (3Al₂O₃・2SiO₂) are typical phases in the Al₂O₃-SiO₂ binary oxide system. Corundum possesses excellent high-temperature strength, corrosion resistance, and mechanical properties, but its high coefficient of thermal expansion results in insufficient thermal shock resistance. Mullite, on the other hand, exhibits good thermal shock resistance and structural stability, with a relatively low coefficient of thermal expansion, but its high-temperature strength and resistance to chlorine corrosion are limited. Therefore, combining the performance advantages of corundum and mullite to overcome their respective shortcomings in thermal shock resistance and corrosion resistance, and preparing corundum-mullite composite saggers is a reasonable technical approach suitable for fly ash sintering conditions.

[0004] However, corundum-mullite saggers, under the coupled environment of "high-temperature thermal cycling + chloride / heavy metal corrosion" in fly ash sintering, still face problems such as grain boundary strength attenuation, thermal stress cracking, and chloride penetration and enrichment, resulting in limited service life. ZrO2 (zirconia), as a ceramic reinforcing phase with phase transformation toughening effect and high corrosion resistance, plays a significant role in improving the thermal shock resistance, inhibiting crack propagation, and enhancing chloride corrosion resistance of corundum-mullite composites. However, the introduction of ZrO2 easily increases the difficulty of material sintering, and precise control of the ratio is required to balance thermal expansion matching and mechanical strength, which poses a challenge to the performance optimization of corundum-mullite saggers.

[0005] In existing technologies, the addition of andalusite to the corundum-mullite sagger used for sintering and solidifying fly ash in waste melting furnaces addresses the issues related to the introduction of zirconium oxide. While this can slightly reduce the coefficient of thermal expansion, the decomposition of andalusite leads to increased porosity and decreased fracture toughness, causing rapid crack propagation during thermal shock. Ultimately, this results in a slight improvement in initial thermal shock resistance at low addition levels, followed by severe degradation over long-term / cyclic thermal shock. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a yttrium oxide-corundum-mullite composite material, its preparation method, and its application. Using yttrium oxide as a modifier and corundum and mullite as raw materials, a yttrium oxide-corundum-mullite composite material with high strength and excellent thermal shock resistance is prepared. By using yttrium oxide as a reinforcing agent, the porosity is significantly reduced, while the thermal stability of the crucible is significantly improved.

[0007] In a first aspect, the present invention provides a yttrium oxide-corundum-mullite composite material. The composite material comprises the following chemical components by mass percentage: 34.3%~34.475% mullite, 63.7%~64.025% corundum, and 1.5%~2% yttrium oxide.

[0008] Preferably, the apparent porosity of the yttrium oxide-corundum-mullite composite material is 17.13%~18.03%; The bulk density of the composite material is 2.40 g / cm³ to 2.44 g / cm³.

[0009] In a second aspect, the present invention provides a method for preparing a yttrium oxide-corundum-mullite composite material. The preparation method includes the following steps: S1. Yttrium oxide, corundum, and mullite are mixed and ball-milled. The grinding media are ceramic balls of mixed sizes. The grinding time is 12 hours and the rotation speed is set to 60 r / min to obtain fine powder material. The mass ratio of yttrium oxide, corundum, and mullite is 1.5%~2%: 63.7%~64.025%: 34.3%~34.475%.

[0010] S2. Using polyvinyl alcohol solution or phenolic resin as a binder, the fine powder material and binder are mixed and pressed into shape at a pressure of 15 MPa for 3 minutes to obtain a green body. Polyvinyl alcohol contains a large number of hydroxyl groups in its molecular chain, which can form a strong adhesion to the surface of the raw material powder through hydrogen bonds. Furthermore, its raw material sources are widely available, its production process is mature, its price is relatively low, it is easily soluble in hot water for easy cleaning, and, more importantly, polyvinyl alcohol is non-toxic and non-irritating, meeting the requirements of green chemistry.

[0011] S3. Sinter the green body to obtain yttrium oxide-corundum-mullite composite material.

[0012] Preferably, the mass ratio of fine powder material to polyvinyl alcohol solution is 10:1, and the concentration of polyvinyl alcohol in polyvinyl alcohol solution is 5 wt%.

[0013] Preferably, the particle size of the fine powder material is 150 mesh to 200 mesh.

[0014] Preferably, the sintering conditions are: calcination at 1300℃~1450℃ for 3h~4h.

[0015] Preferably, the sintering operation is as follows: first, the temperature is increased to 600℃ at 5℃ / min and held for 2 hours; then, the temperature is increased to 1300℃ at 3℃ / min and held for 60 minutes; finally, the temperature is increased to 1300℃~1450℃ at 3℃ / min and held for 4 hours; after the holding period, the temperature is reduced to 800℃ at a rate of 2℃ / min and then allowed to cool naturally.

[0016] Preferably, after pressing and molding in step S2, the process further includes a step of drying the green blank, wherein the drying time is 6 hours and the drying temperature is 100°C.

[0017] Thirdly, this invention provides an application of a yttrium oxide-corundum-mullite composite material. The aforementioned yttrium oxide-corundum-mullite composite material is used in the sintering and solidification of fly ash from a waste melting furnace, specifically as a carrier crucible for the sintering and solidification of fly ash from a waste melting furnace.

[0018] III. Beneficial Effects The yttrium oxide-corundum-mullite composite material provided by this invention uses yttrium oxide as a reinforcing agent in the corundum-mullite system, which significantly reduces porosity and improves the performance of the composite material. By adding 1.5%~2wt% yttrium oxide as a modifier, the flexural strength of the composite material reaches a maximum of 58.53 MPa, which is 131.50% higher than that of corundum-mullite material without yttrium oxide; the apparent porosity is reduced to 17.13%~18.03%, and the bulk density is optimized to 2.4333 g / cm³, with a significant improvement in densification.

[0019] The composite material maintains good strength retention after five thermal shock cycles at 1200℃. Yttrium oxide refines the grains and forms a stable second phase, reducing uneven thermal expansion and grain boundary defects, effectively alleviating thermal stress cracking, and is suitable for high-temperature thermal cycling conditions of fly ash sintering.

[0020] The preparation process adopts the conventional process of ball milling, dry pressing, and atmospheric pressure sintering. The particle size of the fine powder material and the sintering parameters are easy to control. The binder is non-toxic and low-cost polyvinyl alcohol, which meets the requirements of green production and is easy to industrial mass production.

[0021] The material is specifically designed for fly ash sintering and solidification scenarios involving high temperatures of 1200-1300℃ and chloride / heavy metal corrosion. The performance stability of the carrier crucible directly improves the efficiency of fly ash harmless treatment and the service life of the equipment.

[0022] Based on corundum and mullite as raw materials, and modified with yttrium oxide, the excellent properties of the raw materials are retained, while the performance shortcomings of the basic raw materials are made up for through the synergistic effect of yttrium oxide, thereby further improving the overall performance of ceramics. Attached Figure Description

[0023] Figure 1 This is a process flow diagram for preparing the yttrium oxide-corundum-mullite composite material of the present invention; Figure 2 X-ray diffraction comparison diagram of the yttrium oxide-corundum-mullite composite material of Example 1 and the corundum-mullite composite material of Comparative Example 6. Figure 3 SEM image of the yttrium oxide-corundum-mullite composite material of Example 1; Figure 4 The volume density and apparent porosity of the yttrium oxide-corundum-mullite composite material of Example 1 and the corundum-mullite composite material of Comparative Example 6 are shown in the diagram. Figure 5 The diagram shows the flexural strength of the yttrium oxide-corundum-mullite composite material of Example 1 and the corundum-mullite composite material of Comparative Example 6. Figure 6 The diagram shows the flexural strength and strength retention rate of the yttrium oxide-corundum-mullite composite material of Example 1 after five thermal shock cycles at 1200°C. Figure 7 Sintering diagrams of yttrium oxide-corundum-mullite composite materials from Examples 1 to 4 and Comparative Examples 1 to 5 are shown. Figure 8 The diagram shows the flexural strength of the yttrium oxide-corundum-mullite composite materials of Examples 1 to 4, Comparative Examples 1 to 5, and the corundum-mullite composite material of Comparative Example 6. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the data in 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.

[0025] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased on the market or prepared by existing methods.

[0026] Example 1 A method for preparing a yttrium oxide-corundum-mullite composite material includes the following steps: S1. According to the mass fraction ratio of corundum 63.7%, mullite 34.3%, and yttrium oxide 2%, corundum, mullite, and yttrium oxide are thoroughly mixed and ball-milled to obtain fine powder material.

[0027] S2. Using polyvinyl alcohol solution as a binder, the fine powder material and the binder are mixed evenly and then pressed into shape in a tablet press to obtain a green compact.

[0028] S3. The green blank is placed in a muffle furnace for atmospheric pressure sintering. First, the temperature is increased to 600℃ at 5℃ / min and held for 2 hours; then the temperature is increased to 1300℃ at 3℃ / min and held for 60 minutes; finally, the temperature is increased to 1300℃~1450℃ at 3℃ / min and held for 4 hours. After the holding period, the temperature is reduced to 800℃ at a rate of 2℃ / min and then naturally cooled to obtain yttrium oxide-corundum-mullite composite material.

[0029] The yttrium oxide-corundum-mullite composite material obtained in this embodiment has a porosity of 17.13%, a bulk density of 2.4333 g / cm³, and a flexural strength of 58.53 MPa. Compared with the corundum-mullite composite material of Comparative Example 6, its strength is increased by 131.50%.

[0030] Example 2 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 1.5%, and includes the following steps: S1. According to the mass fraction ratio of corundum 64.025%, mullite 34.475%, and yttrium oxide 1.5%, yttrium oxide, corundum, and mullite are thoroughly mixed and ball-milled to obtain fine powder material.

[0031] S2. Using polyvinyl alcohol solution as a binder, the fine powder material and the binder are mixed evenly and then pressed into shape in a tablet press to obtain a green compact.

[0032] S3. The green blank is placed in a muffle furnace for atmospheric pressure sintering. First, the temperature is increased to 600℃ at 5℃ / min and held for 2 hours; then the temperature is increased to 1300℃ at 3℃ / min and held for 60 minutes; finally, the temperature is increased to 1300℃~1450℃ at 3℃ / min and held for 4 hours. After the holding period, the temperature is reduced to 800℃ at a rate of 2℃ / min and then naturally cooled to obtain yttrium oxide-corundum-mullite composite material.

[0033] Example 3 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 1.5% to 1%, and includes the following steps: S1. According to the mass fraction ratio of corundum 64.35%, mullite 34.65%, and yttrium oxide 1%, yttrium oxide, corundum, and mullite are thoroughly mixed and ball-milled to obtain fine powder material.

[0034] S2. Using polyvinyl alcohol solution as a binder, the fine powder material and the binder are mixed evenly and then pressed into shape in a tablet press to obtain a green compact.

[0035] S3. The green blank is placed in a muffle furnace for atmospheric pressure sintering. First, the temperature is increased to 600℃ at 5℃ / min and held for 2 hours; then the temperature is increased to 1300℃ at 3℃ / min and held for 60 minutes; finally, the temperature is increased to 1300℃~1450℃ at 3℃ / min and held for 4 hours. After the holding period, the temperature is reduced to 800℃ at a rate of 2℃ / min and then naturally cooled to obtain yttrium oxide-corundum-mullite composite material.

[0036] Example 4 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 1% to 0.5%, and includes the following steps: S1. According to the mass fraction ratio of corundum 64.675%, mullite 34.825%, and yttrium oxide 0.5%, corundum, yttrium oxide, and mullite are thoroughly mixed and ball-milled to obtain fine powder material.

[0037] S2. Using polyvinyl alcohol solution as a binder, the fine powder material and the binder are mixed evenly and then pressed into shape in a tablet press to obtain a green compact.

[0038] S3. The green blank is placed in a muffle furnace for atmospheric pressure sintering. First, the temperature is increased to 600℃ at 5℃ / min and held for 2 hours; then the temperature is increased to 1300℃ at 3℃ / min and held for 60 minutes; finally, the temperature is increased to 1300℃~1450℃ at 3℃ / min and held for 4 hours. After the holding period, the temperature is reduced to 800℃ at a rate of 2℃ / min and then naturally cooled to obtain yttrium oxide-corundum-mullite composite material.

[0039] Comparative Example 1 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 2.1%, and further, the corundum content is 63.635% and the mullite content is 34.265%, thus obtaining the yttrium oxide-corundum-mullite composite material.

[0040] Comparative Example 2 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 2.2%, and further, the corundum content is 63.57% and the mullite content is 34.23%, thus obtaining the yttrium oxide-corundum-mullite composite material.

[0041] Comparative Example 3 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 2.3%, and further, the corundum content is 63.505% and the mullite content is 34.195%, thus obtaining the yttrium oxide-corundum-mullite composite material.

[0042] Comparative Example 4 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 2.4%, and further, the corundum content is 63.44% and the mullite content is 34.16%, thus obtaining the yttrium oxide-corundum-mullite composite material.

[0043] Comparative Example 5 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 2.5%, and further, the corundum content is 63.375% and the mullite content is 34.125%, thus obtaining the yttrium oxide-corundum-mullite composite material.

[0044] Yttrium oxide can form a low-melting-point phase with the corundum-mullite matrix at high temperatures, acting as a flux during sintering. This effectively promotes grain densification and improves material strength. However, when the amount of yttrium oxide added exceeds its threshold, the sintering performance of the sample deteriorates. When the amount of yttrium oxide added is higher than 2 wt%, the corundum-mullite material exhibits over-burning and peeling during sintering. Excessive low-melting-point phase easily leads to excessive melting at grain boundaries, resulting in decreased material density and strength. The flexural strength of the yttrium oxide-corundum-mullite composite material shows a precipitous drop.

[0045] Comparative Example 6 A method for preparing a yttrium oxide-corundum-mullite composite material is the same as the preparation steps in Example 1, except that the mass fraction of yttrium oxide is replaced from 2% to 0%, and further, the corundum content is 65% and the mullite content is 35%, thus obtaining the corundum-mullite composite material.

[0046] like Figures 1-8 As shown, Figure 1The process clearly presents the complete preparation chain: "raw material mixing and ball milling → binder addition → dry pressing → atmospheric pressure sintering → finished product," emphasizing the simplicity and operability of the process. Alumina, kaolin, and yttrium oxide are mixed evenly in a specific mass ratio. The mixed sample is then placed in a mortar and ground. During grinding, a 5% PVA solution is added at a mass ratio of 10:1 (fine powder to polyvinyl alcohol solution). After complete grinding (150-200 mesh), the sample is pressed into tablets using a tablet press. The pressed sample is then dried in a drying oven for 6 hours before being sintered in a box-type resistance furnace. The sample after long-pressure sintering can be used as a crucible for sintering and solidifying fly ash in a waste melting furnace.

[0047] Figure 2 The phase composition of Example 1 (2 wt% yttrium oxide) was compared with that of Comparative Example 6 (no yttrium oxide), which verified the modification mechanism of yttrium oxide. The main crystalline phases of both were corundum (Al₂O₃) and mullite (3Al₂O₃·2SiO₂), indicating that the addition of yttrium oxide did not change the core phase of the matrix, thus preserving the original basic properties of the material. However, the diffraction pattern of Example 1 showed the presence of yttrium aluminum garnet (Y₃Al₅O₂). 12 The relevant characteristic peaks confirm that yttrium oxide and corundum undergo a solid-phase reaction during high-temperature sintering. The fine crystals of yttrium aluminum garnet can fill the internal pores of corundum-mullite ceramics, promote sintering densification, and refine the grain size, providing a phase basis for improving the material's strength and structural stability.

[0048] Figure 3 The microstructure of the composite material in Example 1 is shown, visually presenting its microstructural characteristics. The mullite (a) and corundum (b) phases are clearly distinguished in the figure. Both phases are uniformly distributed without obvious agglomeration, indicating that the ball milling process effectively achieves uniform dispersion of the raw materials. The microstructure exhibits a low number of small, uniformly distributed pores with no obvious large-size defects, and the grains are fine and uniform, confirming the grain-refining effect of yttrium oxide. Observation of the grain boundaries reveals a tight interface between the corundum, mullite, and yttrium aluminum garnet phases, with no obvious cracks. The phases exhibit good compatibility and can collaboratively withstand external forces and thermal stresses, laying a structural foundation for improving the material's mechanical properties and thermal shock resistance.

[0049] Figure 4 The effect of varying yttrium oxide (YO) content on the physicochemical properties of the material was demonstrated. As the YOO content increased from 0 to 2 wt%, the apparent porosity decreased from approximately 20.56% to 17.13%, while the bulk density increased from approximately 2.3005 g / cm³ to 2.4333 g / cm³, indicating a significant improvement in densification. This demonstrates that at a content of 2 wt%, YOO can effectively inhibit pore formation and fill existing pores.

[0050] Figure 5This directly demonstrates the quantitative correlation between the amount of yttrium oxide added and the flexural strength. As the amount of yttrium oxide increased from 0 to 2 wt%, the flexural strength showed a continuous increasing trend, steadily rising from approximately 25.28 MPa in Comparative Example 6 (without yttrium oxide) to 58.53 MPa in Example 1 (2 wt% yttrium oxide), representing a strength increase of up to 131.50%. The strength increase was particularly significant in the 1.5%~2 wt% range, with Example 2 (1.5 wt% yttrium oxide) achieving a flexural strength of 54.37 MPa, close to the peak level. The increase in strength also reflects the improved material densification; an appropriate amount of yttrium oxide can fill pores and refine grains by generating yttrium aluminum garnet phase, thus strengthening grain boundary bonding.

[0051] Figure 6 Focusing on the thermal shock resistance of materials under simulated real-world conditions, the advantages of yttrium oxide modification were comprehensively verified through residual flexural strength and strength retention rate. Example 1 (2wt% yttrium oxide) maintained a flexural strength above 50 MPa after five thermal shock cycles at 1200℃, with a strength retention rate exceeding 97%, significantly better than the strength retention rate of Comparative Example 6 (without yttrium oxide) (approximately 75%). During thermal shock, the material without yttrium oxide, due to its coarse grains and numerous grain boundary defects, was prone to cracking and rapid propagation under thermal stress, leading to a significant decrease in strength. In contrast, the composite material containing yttrium oxide, with its refined uniform grain structure, the formed stable second phase (yttrium aluminum garnet), and optimized grain boundary bonding, effectively reduced internal stress caused by uneven thermal expansion, suppressing crack initiation and propagation. From a microscopic perspective, yttrium oxide, by regulating the thermal expansion coefficient of the material and strengthening the grain boundary bonding force, enables the material to maintain its structural integrity during repeated heating and cooling processes. This performance characteristic is precisely adapted to the harsh working conditions of "high-temperature thermal cycling + erosion" in the sintering of fly ash in waste melting furnaces. It solves the core pain point of performance degradation of traditional corundum-mullite materials after long-term thermal shock, and provides a key guarantee for the long-term stable operation of the carrier crucible.

[0052] Figure 7The significant impact of yttrium oxide (YO) addition on sintering performance was clearly demonstrated through a direct comparison of the morphology. When the YOO addition was in the range of 0.5%–2 wt% (Examples 1–4), the composite material surface was smooth and flat, without peeling, cracking, or deformation, exhibiting a uniform and stable sintering state. This indicates that an appropriate amount of YOO can promote grain diffusion and densification, achieving uniform sintering. When the YOO addition exceeded 2 wt% (Comparative Examples 1–5), obvious over-burning peeling occurred on the material surface. Some samples showed slight deformation and grain boundary melt flow marks. This was because excessive YOO formed a large amount of low-melting phase with the matrix, leading to excessive melting of grain boundaries during sintering, which damaged the surface structure and internal density of the material. Furthermore, comparing the sintering shrinkage rates of the examples and comparative examples revealed that with a YOO addition of 1.5%–2 wt%, the material shrank uniformly without localized excessive or insufficient shrinkage, while the excessive addition group showed larger fluctuations in shrinkage rate, further confirming the threshold effect of YOO addition.

[0053] Figure 8 The flexural strength data of all examples, comparative examples, and blank control groups were integrated to form a complete performance comparison system. From the overall trend, the relationship between yttrium oxide addition and flexural strength showed a significant "first increase, then decrease" pattern: the flexural strength of Examples 1-4 (yttrium oxide 0.5%-2wt%) was higher than that of Comparative Example 6 (no yttrium oxide), reaching a peak in the 1.5%-2wt% range. Example 1 (2wt%) had the highest strength (58.53 MPa), followed by Example 2 (1.5wt%) (54.37 MPa). The strengths of Examples 3 (1wt%) and 4 (0.5wt%) were 52.08 MPa and 50.31 MPa, respectively, both remaining above 50 MPa. In contrast, the strength of Comparative Examples 1-5 (yttrium oxide 2.1%-2.5wt%) decreased rapidly, with a greater decrease in strength at higher addition levels. The strength of Comparative Example 5 (2.5wt%) dropped to 40.26 MPa, lower than the performance level of Example 4. Figure 8 By comparing data from multiple groups, we not only clarified the optimal addition range of yttrium oxide (1.5%~2wt%), but also confirmed, through the stark contrast with the blank control group and the excessive addition group, that by precisely controlling the amount of yttrium oxide added, we can achieve a breakthrough improvement in the mechanical properties of materials, while avoiding performance degradation caused by excessive addition.

[0054] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

Claims

1. A yttrium oxide-corundum-mullite composite material, characterized in that, The chemical composition includes the following percentages by mass: mullite 34.3%~34.475%, corundum 63.7%~64.025%, and yttrium oxide 1.5%~2%; The apparent porosity of the composite material is 17.13%~18.03%; The bulk density of the composite material is 2.40 g / cm³ to 2.44 g / cm³. The composite material includes a corundum phase, a mullite phase, and a yttrium aluminum garnet phase. The yttrium aluminum garnet phase is generated by a solid-phase reaction between yttrium oxide and corundum during high-temperature sintering.

2. A method for preparing a yttrium oxide-corundum-mullite composite material, characterized in that, Includes the following steps: S1. Mix yttrium oxide, corundum, and mullite in a mass ratio of 1.5~2:63.7~64.025:34.3~34.475 and place them in a drum mill for tumbling. The tumbling media are ceramic balls of mixed sizes. The tumbling time is 12 hours and the rotation speed is set to 60 r / min. S2. After the fine powder material is mixed evenly with the binder, it is pressed into shape by a tablet press at a pressure of 15MPa and a holding time of 3min to obtain a green compact. S3. The green body is sintered to obtain a yttrium oxide-corundum-mullite composite material.

3. The yttrium oxide-corundum-mullite composite material according to claim 2, characterized in that, The particle size of the fine powder material is 150 mesh to 200 mesh.

4. The yttrium oxide-corundum-mullite composite material according to claim 2, characterized in that, The binder is a polyvinyl alcohol solution or phenolic resin; when the binder is a polyvinyl alcohol solution, the mass concentration of the polyvinyl alcohol solution is 5 wt%, and the mass ratio of the fine powder material to the polyvinyl alcohol solution is 10:

1.

5. The yttrium oxide-corundum-mullite composite material according to claim 2, characterized in that, The sintering temperature is 1300℃~1450℃, and the holding time is 3h~4h.

6. The yttrium oxide-corundum-mullite composite material according to claim 2, characterized in that, The specific steps of the sintering process are as follows: First, heat the temperature to 600℃ at a heating rate of 5℃ / min and hold for 2 hours; Then raise the temperature to 1300℃ at a heating rate of 3℃ / min and hold for 60min; Finally, the temperature was increased to 1300℃~1450℃ at a heating rate of 3℃ / min and held for 4 hours. After the heat preservation is completed, the temperature is reduced to 800℃ at a cooling rate of 2℃ / min, and then allowed to cool naturally to room temperature.

7. The yttrium oxide-corundum-mullite composite material according to claim 2, characterized in that, After pressing and molding in step S2, the process also includes drying the green blank.

8. The yttrium oxide-corundum-mullite composite material according to claim 7, characterized in that, The drying process takes 6 hours and the drying temperature is 100°C.

9. The application of the yttrium oxide-corundum-mullite composite material as described in claim 1, characterized in that, The composite material is applied to the field of fly ash sintering and solidification in waste melting furnaces.

10. The application according to claim 9, characterized in that, The composite material is used as a carrier crucible for the sintering and solidification of fly ash in a waste melting furnace.

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