Highly dense Y2O3-CaO-MgO-Al2O3 composite refractory and preparation method thereof

Abstract

This invention relates to the field of refractory materials technology, and more particularly to a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material and its preparation method. The components and their mass percentages of the refractory material are: Y2O3 4%–6%, CaYAl3O 73%–8%, CaAl2O 45%–7%, Al5Y3O 12 The composite refractory material contains 16%–25% CaAl4O7, 21%–25% CaAl2O4, and 30%–45% MgAl2O4. Its preparation method includes raw material pretreatment and sieving, mixing, molding, drying, and high-temperature sintering. The composite refractory material proposed in this invention avoids the problem of carbon addition to clean steel by traditional carbon-containing refractory materials and improves the sintering performance and thermal shock resistance of traditional CaO-MgO-Al2O3 materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory materials, in particular to a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the metallurgical industry, based on the demand for environmental protection, resource conservation, product quality and technological progress, clean steel emerged as the times require, and the production of clean steel needs high-quality advanced functional refractories to achieve the metallurgical purpose. At present, the research on refractories used in clean steel smelting mainly focuses on developing materials that can withstand harsh conditions in modern steel production processes and maintain high performance and long service life. Researchers are committed to improving the thermal shock resistance, corrosion resistance and corrosion resistance of refractories to optimize their service life and efficiency in clean steel production practice. In view of the problems encountered in the clean steel smelting process, such as oxygen increase, carbon increase and increase of non-metallic inclusions, researchers are exploring new refractories with improved performance, such as new magnesium-carbon refractories, by adding various additives to improve the structure of the refractories, improve their thermal shock resistance, or add some antioxidants to improve the oxidation resistance of magnesium-carbon refractories, and improve their service life. The contradiction between the coupling promotion of the thermal shock resistance, oxidation resistance and slag erosion resistance of low-carbon magnesium-carbon refractories lies in the reasonable control of carbon content, and as a result, additives need to be introduced, and the aggregate and matrix raw materials of the refractories may also need to be modified. The CaO-MgO-Al2O3(CMA) powder is a solid solution of MgAl2O4, CaAl4O7 and CaAl2O4, which has the advantages of high melting point, low thermal conductivity, good thermal shock resistance and thermal reduction resistance, etc. In addition, Y2O3 refractory material is currently a kind with high chemical stability, which is not easy to react with trace elements in clean steel for a long time, and the incorporation of Y2O3 into the composite can further improve the high-temperature corrosion resistance of CaO-MgO-Al2O3 composite material. However, the composition of CMA material changes complexly in the high-temperature reaction process, and it is difficult to realize its densification, and although the use of advanced forming and sintering technology is effective, the synthesis cost is increased, which is not conducive to industrialization. Therefore, the research on the sintering properties of Y2O3-CaO-MgO-Al2O3 refractories is of great significance to the development of new clean steel smelting refractories. SUMMARY

[0003] In view of this, the present application aims to solve the defects of the prior art, and proposes a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material and a preparation method thereof to solve the problem of complex composition change of CMA material in the high-temperature reaction process and the difficulty in realizing its densification.

[0004] To achieve the above objectives, this invention provides a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the composition and its mass percentages of which are: Y2O3 4%–6%, CaYAl3O 73%–8%, CaAl2O 45%–7%, Al5Y3O 12 16% ~ 25%, CaAl4O7 21% ~ 25%, MgAl2O4 30% ~ 45%.

[0005] This invention also proposes a method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, comprising the following steps:

[0006] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed, and the crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder.

[0007] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additive (20-40):(15-55):(10-30):(0-10), and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 250-320 r·min. -1 Ball milling at a certain speed for 6–10 hours yields a uniformly mixed raw material;

[0008] Step 3, Shaping: Add 2% to 5% by weight of binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press the raw material into a green body under 100 to 250 MPa.

[0009] Step 4: Drying: Dry the pressed green bodies in batches in a hot air drying oven at 100-120℃ for 10-12 hours.

[0010] Step 5, High-temperature sintering: The dried green blanks are heated to 1500-1600℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 2-5 hours. The final product is obtained by cooling in the furnace.

[0011] Optionally, the additive is composed of one or more of YSZ, CA6 and TiO2.

[0012] Optionally, in step one, the chemical composition of CaO-MgO-Al2O3 is 63%–80% Al2O3, 4%–10% MgO, 4%–6% CaO, and the loss on ignition is 4%–15%.

[0013] Optionally, the industrial Y2O3 in step one has a chemical composition of Y2O3 95%-99%, Al2O3 0-1%, MgO 0-1%, SiO2 0-1%, and a loss on ignition of 0-1%.

[0014] Optionally, the binder in step three is one or a combination of polyvinyl alcohol and liquid phenolic resin.

[0015] The Y2O3-CaO-MgO-Al2O3 composite refractory material and the preparation method thereof have the following advantages: compared with the traditional low-carbon magnesia-carbon refractory material for clean steel smelting, the Y2O3-CaO-MgO-Al2O3 composite refractory material avoids the problem of carbon pick-up in the clean steel. The carbon component in the low-carbon magnesia-carbon refractory material is easy to react with oxygen to generate CO or CO2 gas at high temperature, while the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared by the method does not contain carbon, so there is no such problem. Therefore, in the process of smelting clean steel, the use of the Y2O3-CaO-MgO-Al2O3 composite refractory material can reduce the secondary oxidation of molten steel caused by the oxidation of the refractory material, and further improve the cleanliness of the steel; compared with the low-carbon magnesia-carbon refractory material, the components Al2O3, MgO, and CaO have a lower oxygen potential, and the Y2O3-CaO-MgO-Al2O3 has a smaller reactivity with the molten steel, which means that there is less chemical reaction between them and the molten steel during the smelting process, which helps to reduce the generation of chemical inclusions and improve the purity of the steel. Although the material contains CaO, the CaO will not hydrolyze in the system and will react with Al2O3 to generate CaAl2O4 and CaAl4O7, and there is a tendency to further react to generate 12CaO·7Al2O3, which avoids the problem of material hydration. The various oxides in the Y2O3-CaO-MgO-Al2O3 composite refractory material can react with non-metallic inclusions in the molten steel to form compounds that are easy to float to the surface of the molten steel, which helps to reduce the number and size of inclusions and improve the internal quality of the steel. The oxide combination designed in the application controls the mass content of each component, so that the Y2O3-CaO-MgO-Al2O3 composite refractory material can maintain a high mechanical strength at high temperature, which helps the refractory material to resist mechanical wear and structural damage during the smelting process and prolong its high-temperature service life. The sintering performance and thermal shock resistance of the traditional CaO-MgO-Al2O3 material are also improved, and the prepared product has a higher degree of densification and better comprehensive performance. BRIEF DESCRIPTION OF DRAWINGS

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is an electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Example 4 of the present invention;

[0018] Figure 2 This is an electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Example 5 of the present invention;

[0019] Figure 3 This is a backscattered electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Example 6 of the present invention;

[0020] Figure 4 This is a backscattered electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Example 7 of the present invention;

[0021] Figure 5 This is an electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Example 8 of the present invention;

[0022] Figure 6 This is an electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Example 9 of the present invention;

[0023] Figure 7 This is an electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Comparative Example 1 of this invention;

[0024] Figure 8 This is an electron microscope image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in Comparative Example 2 of this invention; Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0026] Example 1

[0027] This invention proposes a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the composition and its mass percentages of which are: Y2O3 4%, CaYAl3O 77%, CaAl2O 45%, Al5Y3O 1221%, CaAl4O722%, MgAl2O441%.

[0028] Example 2

[0029] This invention proposes a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the composition and its mass percentages of which are: Y2O3 5%, CaYAl3O 74%, CaAl2O 45%, Al5Y3O 12 18%, CaAl4O725%, MgAl2O443%.

[0030] Example 3

[0031] This invention proposes a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the composition and its mass percentages of which are: Y2O3 5%, CaYAl3O 78%, CaAl2O 47%, Al5Y3O 12 22%, CaAl4O721%, MgAl2O437%.

[0032] Example 4

[0033] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0034] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed. The crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. The chemical composition of CaO-MgO-Al2O3 is 71% Al2O3, 10% MgO, 4% CaO, and 15% loss on ignition.

[0035] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 20:55:25:1, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 250 r·min. -1 The mixture was ball-milled at a certain speed for 8 hours to form a uniformly mixed raw material, wherein the chemical composition of Y2O3 was 96% Y2O3, 1% Al2O3, 1% MgO, 1% SiO2, and 1% loss on ignition.

[0036] Step 3, Molding: Add 2% by weight of thermosetting phenolic resin binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body at 220MPa.

[0037] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 11 hours in a hot air drying oven;

[0038] Step 5, High-temperature sintering: The dried green blanks are heated to 1500℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 4 hours. The final product is obtained by cooling with the furnace.

[0039] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this example are: apparent porosity of 3.2% and bulk density of 3.3 g·cm³. -3 The linear shrinkage rate is 15.8%, the volume shrinkage rate is 18.4%, the compressive strength at room temperature is 152 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 56%. Figure 1 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0040] Example 5

[0041] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0042] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed. The crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. The chemical composition of CaO-MgO-Al2O3 is 75% Al2O3, 8% MgO, 5% CaO, and the loss on ignition is 12%.

[0043] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 40:35:25:3, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 320 r·min. -1 The mixture was ball-milled at a certain speed for 9 hours to form a uniformly mixed raw material. The chemical composition of Y2O3 was 97% Y2O3, 0% Al2O3, 1% MgO, 1% SiO2, and 1% loss on ignition.

[0044] Step 3, Molding: Add 3% by weight of polyvinyl alcohol binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body under 200 MPa.

[0045] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 10 hours in a hot air drying oven;

[0046] Step 5, High-temperature sintering: The dried green blanks are heated to 1540℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 3 hours. The final product is obtained by cooling in the furnace.

[0047] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y₂O₃-CaO-MgO-Al₂O₃ composite refractory material prepared in this example are: apparent porosity of 3.4% and bulk density of 3.2 g·cm³. -3 The linear shrinkage rate is 12.6%, the volume shrinkage rate is 14.6%, the compressive strength at room temperature is 166 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 95%. Figure 2 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0048] Example 6

[0049] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0050] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed. The crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. The chemical composition of CaO-MgO-Al2O3 is 80% Al2O3, 4% MgO, 6% CaO, and 10% loss on ignition.

[0051] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 60:15:25:5, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 280 r·min. -1 The mixture was ball-milled at a certain speed for 10 hours to form a uniformly mixed raw material. The chemical composition of Y2O3 was 99% Y2O3, 0% Al2O3, 0% MgO, 0% SiO2, and 1% loss on ignition.

[0052] Step 3, Molding: Add 5% by weight of phenolic resin binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body under 250MPa.

[0053] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 12 hours in a hot air drying oven;

[0054] Step 5, High-temperature sintering: The dried green blanks are heated to 1580℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 2 hours. The final product is obtained by cooling with the furnace.

[0055] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y₂O₃-CaO-MgO-Al₂O₃ composite refractory material prepared in this example are: apparent porosity of 7.8% and bulk density of 3.0 g·cm³. -3 The linear shrinkage rate is 8.6%, the volume shrinkage rate is 11.1%, the compressive strength at room temperature is 142 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 78%. Figure 3 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0056] Example 7

[0057] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0058] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed. The crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. The chemical composition of CaO-MgO-Al2O3 is 78% Al2O3, 5% MgO, 6% CaO, and the loss on ignition is 11%.

[0059] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 40:35:25:2, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 320 r·min. -1 The mixture was ball-milled at a certain speed for 8 hours to form a uniformly mixed raw material, wherein the chemical composition of Y2O3 was 95% Y2O3, 1% Al2O3, 1% MgO, 1% SiO2, and 1% loss on ignition.

[0060] Step 3, Molding: Add 4% by mass of polyvinyl alcohol binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body under 250 MPa.

[0061] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 10 hours in a hot air drying oven;

[0062] Step 5, High-temperature sintering: The dried green blanks are heated to 1500℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 3 hours. The final product is obtained by cooling with the furnace.

[0063] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y₂O₃-CaO-MgO-Al₂O₃ composite refractory material prepared in this example are: apparent porosity of 4.5% and bulk density of 3.2 g·cm³. -3 The linear shrinkage rate is 6.6%, the volumetric shrinkage rate is 15.5%, the compressive strength at room temperature is 155 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 76%. Figure 4 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0064] Example 8

[0065] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0066] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed. The crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. The chemical composition of CaO-MgO-Al2O3 is 71% Al2O3, 10% MgO, 4% CaO, and 15% loss on ignition.

[0067] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 40:35:25:2, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 280 r·min. -1 The mixture was ball-milled at a certain speed for 9 hours to form a uniformly mixed raw material, wherein the chemical composition of Y2O3 was 97%, Al2O3 was 1%, MgO was 1%, SiO2 was 1%, and the loss on ignition was 0%.

[0068] Step 3, Molding: Add 3% by weight of thermosetting phenolic resin binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body at 180MPa.

[0069] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 12 hours in a hot air drying oven;

[0070] Step 5, High-temperature sintering: The dried green blanks are heated to 1540℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 3 hours. The final product is obtained by cooling in the furnace.

[0071] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y₂O₃-CaO-MgO-Al₂O₃ composite refractory material prepared in this example are: apparent porosity of 4.2% and bulk density of 3.4 g·cm³. -3 The linear shrinkage rate is 7.5%, the volumetric shrinkage rate is 18.4%, the compressive strength at room temperature is 173 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 92%. Figure 5 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0072] Example 9

[0073] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0074] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed. The crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. The chemical composition of CaO-MgO-Al2O3 is 69% Al2O3, 10% MgO, 6% CaO, and 15% loss on ignition.

[0075] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 40:35:25:6, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 300 r·min. -1 The mixture was ball-milled at a certain speed for 10 hours to form a uniformly mixed raw material. The chemical composition of Y2O3 was 97% Y2O3, 1% Al2O3, 1% MgO, 1% SiO2, and 0% loss on ignition.

[0076] Step 3, Molding: Add 2% by weight of polyvinyl alcohol binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body under 220 MPa.

[0077] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 11 hours in a hot air drying oven;

[0078] Step 5, High-temperature sintering: The dried green blanks are heated to 1580℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 3 hours. The final product is obtained by cooling with the furnace.

[0079] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this example are: apparent porosity of 4.4% and bulk density of 3.5 g·cm³. -3 The linear shrinkage rate is 9.4%, the volumetric shrinkage rate is 21.6%, the room temperature compressive strength is 212 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 97%. Figure 6 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0080] Comparative Example 1

[0081] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0082] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed, and the crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve.

[0083] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 0:65:35:4, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 320 r·min. -1 Ball milling at a certain speed for 9 hours yielded a uniformly mixed raw material;

[0084] Step 3, Molding: Add 4% by weight of polyvinyl alcohol binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body under 250 MPa.

[0085] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 11 hours in a hot air drying oven;

[0086] Step 5, High-temperature sintering: The dried green blanks are heated to 1560℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 4 hours. The final product is obtained by cooling with the furnace.

[0087] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this example are: apparent porosity of 2.7% and bulk density of 3.5 g·cm³. -3 The linear shrinkage rate is 22.7%, the volume shrinkage rate is 16.3%, the room temperature compressive strength is 84.4 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 41%. Figure 7 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0088] Comparative Example 2

[0089] A method for preparing a high-density Y2O3-CaO-MgO-Al2O3 composite refractory material, the specific operation steps of which are as follows:

[0090] Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed, and the crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are sieved through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder.

[0091] Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additives of 65:0:35:4, and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 300 r·min. -1 Ball milling at a certain speed for 10 hours yields a uniformly mixed raw material;

[0092] Step 3, Molding: Add 4% by weight of polyvinyl alcohol binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the raw material thoroughly to mix the binder with the raw material. Finally, press it into a green body under 240 MPa.

[0093] Step 4: Drying: Dry the pressed green bodies in batches at 120°C for 12 hours in a hot air drying oven;

[0094] Step 5, High-temperature sintering: The dried green blanks are heated to 1520℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 4 hours. The final product is obtained by cooling with the furnace.

[0095] The phase composition, microstructure, apparent porosity, bulk density, linear shrinkage, room temperature compressive strength, and residual strength retention (to characterize thermal shock resistance) of the samples were determined. The performance indicators of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this example are: apparent porosity of 2.4% and bulk density of 2.5 g·cm³. -3 The linear shrinkage rate is 2.4%, the volume shrinkage rate is 4.9%, the compressive strength at room temperature is 113 MPa, and the residual strength retention rate after two air quenchings at 1100℃ is 65%. Figure 8 This is a SEM image of the Y2O3-CaO-MgO-Al2O3 composite refractory material prepared in this embodiment.

[0096] The following table compares and analyzes the performance indicators of the Y2O3-CaO-MgO-Al2O3 composite refractory materials prepared in the above examples and comparative examples:

[0097]

[0098] Comparative Example 1 only added CMA fine powder without CMA aggregate, and Comparative Example 2 only added CMA aggregate without CMA fine powder. Compared with other examples that added both CMA aggregate and CMA fine powder, their final physical properties were worse. CMA aggregate is a refractory particle that plays a major role in supporting the strength and performance of refractory materials and is a core component of refractory materials. The addition of CMA powder can fill the voids between aggregates and promote solid-phase sintering. Therefore, composite refractory materials that simultaneously add CMA aggregate and CMA fine powder can improve the sintering performance and room-temperature mechanical properties of refractory materials. Their final physical properties are as follows: apparent porosity of 3.2% to 7.8% and bulk density of 3.0 to 3.5 g·cm³. -3 The room temperature compressive strength is 142-212 MPa, and the residual strength retention rate is 56%-97%, indicating that the refractory material prepared by this method has excellent thermal shock resistance and can be used for the smelting of low-carbon clean steel.

[0099] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0100] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A high-density Y₂O₃-CaO-MgO-Al₂O₃ composite refractory material, characterized in that, Its components and their mass percentages are: Y₂O₃ 4%~6%, CaYAl₃O₇ 73%~8%, CaAl₂O₇ 45%~7%, Al₅Y₃O₇ 12 16%~25%, CaAl4O721%~25%, MgAl2O430%~45%; The preparation method of the composite refractory material includes the following steps: Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed, and the crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are screened through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additive (20~40):(15~55):(10~30):(1~10), and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 250~320 r·min. -1 Ball milling at a certain speed for 6-10 hours yields a uniformly mixed raw material; Step 3, Shaping: Add 2% to 5% by weight of binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the material thoroughly to mix the binder with the raw material. Finally, press the raw material into a green body under 100 to 250 MPa. Step 4: Drying: Dry the pressed green bodies in batches in a hot air drying oven at 100~120℃ for 10~12 hours. Step 5, High-temperature sintering: The dried green blanks are heated to 1500~1600℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 2~5 hours. The final product is obtained by cooling with the furnace.

2. The method for preparing the composite refractory material as described in claim 1, characterized in that, Includes the following steps: Step 1: Raw material pretreatment and sieving: The CaO-MgO-Al2O3 aggregate is fully crushed, and the crushed industrial CaO-MgO-Al2O3 powder and industrial Y2O3 powder are screened through a 200-mesh sieve to obtain fine CaO-MgO-Al2O3 powder and fine Y2O3 powder. Step 2, Mixing: Weigh the pretreated raw materials according to the mass ratio of CaO-MgO-Al2O3 aggregate: CaO-MgO-Al2O3 fine powder: Y2O3 fine powder: additive (20~40):(15~55):(10~30):(1~10), and then use ethanol as the ball milling medium in a high-energy planetary ball mill at 250~320 r·min. -1 Ball milling at a certain speed for 6-10 hours yields a uniformly mixed raw material; Step 3, Shaping: Add 2% to 5% by weight of binder to the ball-milled raw material. During the addition process, use a mortar and pestle to grind the material thoroughly to mix the binder with the raw material. Finally, press the raw material into a green body under 100 to 250 MPa. Step 4: Drying: Dry the pressed green bodies in batches in a hot air drying oven at 100~120℃ for 10~12 hours. Step 5, High-temperature sintering: The dried green blanks are heated to 1500~1600℃ in a high-temperature furnace or tunnel kiln according to different batches and held at that temperature for 2~5 hours. The final product is obtained by cooling with the furnace.

3. The preparation method according to claim 2, characterized in that, The additive is composed of one or more of YSZ, CA6 and TiO2.

4. The preparation method according to claim 2, characterized in that, The mass percentages of the chemical composition of CaO-MgO-Al2O3 in step one are: Al2O3 63%~80%, MgO 4%~10%, CaO 4%~6%, and loss on ignition 4~15%.

5. The preparation method according to claim 2, characterized in that, The mass percentages of the chemical composition of industrial Y2O3 in step one are: Y2O3 95%~99%, Al2O3 0~1%, MgO 0~1%, SiO2 0~1%, and loss on ignition 0~1%.

6. The preparation method according to claim 2, characterized in that, The adhesive used in step three is one or a combination of polyvinyl alcohol and liquid phenolic resin.

Images