High-density refractory ceramic material and method for producing the same

Abstract

This invention relates to the field of ceramic refractory materials technology, specifically to a high-density refractory ceramic material and its preparation method, comprising the following raw materials in parts by weight: 18-24 parts ceramic powder, 15-18 parts fused white corundum aggregate, 12-16 parts fused white corundum fine powder, 9-15 parts metallic silicon powder, 3-5 parts nitride powder, 4-7 parts sintering aid, 1-2 parts lubricant, and 2-4 parts binder. The high density and uniform microstructure of this invention endow the material with excellent high-temperature strength, thermal shock resistance, and resistance to slag erosion. Its service life is more than 30% longer than traditional corundum refractories. Through drying, aging, segmented sintering, and pressure control, the nitriding reaction process and sintering densification are precisely controlled, avoiding excessive shrinkage or cracking, making it suitable for the preparation of complex-shaped components. The diverse selection of sintering aids enhances formulation flexibility, facilitating industrial promotion. The use of a nitrogen atmosphere for sintering results in no toxic emissions, and medium-temperature sintering reduces energy consumption by 20%-30%, aligning with the trend of green manufacturing.

Description

Technical Field

[0001] This invention relates to the field of ceramic refractory materials technology, and more specifically, to a high-density refractory ceramic material and its preparation method. Background Technology

[0002] Refractory ceramic materials are widely used in high-temperature industries such as steel, non-ferrous metals, glass, and cement. Their performance directly affects equipment lifespan, energy efficiency, and production safety. Traditional refractory materials are often based on oxides, which, while possessing good refractoriness, have limitations in density, thermal shock resistance, erosion resistance, and mechanical strength. For example, ordinary corundum refractories have high sintering temperatures and insufficient density, making them prone to pores and microcracks. This leads to decreased strength and increased permeability at high temperatures, making it difficult to meet the modern industrial demands for long service life and high reliability.

[0003] In recent years, nitride-bonded ceramics have attracted attention due to their high hardness, excellent thermal shock resistance and chemical inertness. However, their preparation usually relies on high-purity raw materials and complex processes, which are costly and make it difficult to form large-sized components. At the same time, problems such as poor uniformity of raw material mixing, incomplete removal of binders and insufficient densification during traditional preparation can easily lead to uneven internal structure of the material and affect the consistency of performance.

[0004] To address the aforementioned issues, existing technologies attempt to improve density and strength by adding metallic silicon powder and reacting it in a nitrogen atmosphere to form a silicon nitride bonding phase. However, this process often faces challenges such as incomplete nitriding, uneven distribution of sintering aids, and cracking of the green body, resulting in insufficient final material density and large fluctuations in mechanical properties. Therefore, there is an urgent need to develop a high-density refractory ceramic material and its preparation method to solve these problems. Summary of the Invention

[0005] The purpose of this invention is to provide a high-density refractory ceramic material and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-density refractory ceramic material and its preparation method, comprising the following raw materials in parts by weight: 18-24 parts of ceramic powder, 15-18 parts of fused white corundum aggregate, 12-16 parts of fused white corundum fine powder, 9-15 parts of metallic silicon powder, 3-5 parts of nitride powder, 4-7 parts of sintering aid, 1-2 parts of lubricant, and 2-4 parts of binder.

[0007] As a preferred technical solution of the present invention, the raw materials include the following parts by weight: 20 parts of ceramic powder, 16 parts of fused white corundum aggregate, 14 parts of fused white corundum fine powder, 12 parts of metallic silicon powder, 4 parts of nitride powder, 6 parts of sintering aid, 1 part of lubricant and 3 parts of binder.

[0008] As a preferred technical solution of the present invention, the following steps are included: S1. First, the proportioned ceramic powder, fused white corundum aggregate, fused white corundum fine powder, metallic silicon powder and nitride powder are dried at 150-200℃ for 4 hours to remove adsorbed water. Then, the dried powder and sintering aid are put into a mixer and mixed thoroughly to obtain a primary treatment mixture. S2. Mix water, lubricant and binder evenly first, then slowly add the primary treatment mixture and continue stirring until a uniform slurry is formed to obtain the secondary treatment mixture. Seal the evenly mixed mud and let it stand in a cool environment for 20-32 hours. S3. Place the clay material in a steel mold and press it under an isostatic pressure of 100-120MPa to obtain a green blank with high green body strength. S4. Place the green blank in a nitrogen atmosphere sintering furnace, heat it to 650°C at a rate of 2-4°C / min, hold it for 75 minutes, and pass it through the sintering furnace to completely remove the binder. Then, continue to heat it to 1200-1300°C at a rate of 3-5°C / min, and hold it at this temperature for 2-3 hours to carry out the pre-nitriding reaction. S5. Maintain a nitrogen atmosphere, increase the pressure inside the furnace to 2-10 MPa, and continue to heat to the target sintering temperature of 1580-1680℃ at a rate of 5-8℃ / min, and hold at this temperature for 3-4 hours. S6. After the heat preservation is completed, stop heating and cool the furnace to below 800°C while maintaining nitrogen pressure. Then release the pressure and continue cooling to room temperature. Finally, perform necessary surface grinding and polishing on the sintered body to achieve the required precise dimensions and surface finish, and obtain the final product. S7. Perform density measurement, mechanical property testing and microstructure observation on the finished product to ensure that it meets the performance standards of high-density refractory ceramics.

[0009] As a preferred embodiment of the present invention, the mixing time of the mixer in step S1 is 40-65 minutes until it is initially uniform.

[0010] As a preferred technical solution of the present invention, the sealing and placing in a cool environment in step S2 helps to further distribute moisture evenly, eliminate internal stress, and allow the organic binder to work fully, thereby improving the plasticity of the clay.

[0011] As a preferred technical solution of the present invention, in step S2, the surface of the metallic silicon powder begins to react with nitrogen to generate a Si3N4 layer, forming a preliminary ceramic bonding network, but the reaction is not complete.

[0012] As a preferred embodiment of the present invention, the sintering aid is one or more of yttrium oxide, calcium oxide, and silicon dioxide.

[0013] As a preferred embodiment of the present invention, the binder is one or more of polyvinyl alcohol, methylcellulose, or lignin sulfonate.

[0014] As a preferred embodiment of the present invention, the lubricant is one or more of zinc stearate, calcium stearate, or paraffin wax.

[0015] As a preferred embodiment of the present invention, the main chemical components of the ceramic powder are alumina and silicon carbide.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention is a high-density refractory ceramic material and its preparation method. The high density and uniform microstructure of this invention endow the material with excellent high-temperature strength, thermal shock resistance and slag erosion resistance. The service life is more than 30% longer than that of traditional corundum refractory materials. Through drying, aging, segmented sintering and pressure control, the nitriding reaction process and sintering densification are precisely controlled to avoid excessive shrinkage or cracking. It is suitable for the preparation of complex shaped components.

[0017] (2) This invention is a high-density refractory ceramic material and its preparation method. This invention uses common ceramic powder and fused white corundum, reduces costs by in-situ nitriding of metal silicon powder, enhances the flexibility of the formulation by multiple selection of sintering aids, and is conducive to industrial promotion. Nitrogen atmosphere sintering has no toxic emissions, and medium-temperature sintering reduces energy consumption by 20%-30%, which is in line with the trend of green manufacturing. Detailed Implementation

[0018] Example 1 Example 1 includes the following raw materials in parts by weight: 18-24 parts ceramic powder, 15-18 parts fused white corundum aggregate, 12-16 parts fused white corundum fine powder, 9-15 parts metallic silicon powder, 3-5 parts nitride powder, 4-7 parts sintering aid, 1-2 parts lubricant, and 2-4 parts binder. The composition includes 20 parts ceramic powder, 16 parts fused white corundum aggregate, 14 parts fused white corundum fine powder, 12 parts metallic silicon powder, 4 parts nitride powder, 6 parts sintering aid, 1 part lubricant, and 3 parts binder. In this embodiment, the high-pressure nitrogen atmosphere sintering effectively suppresses the formation of pores, enabling the material's theoretical density to reach over 98% and its porosity to be less than 2%. The sintering aid promotes uniform distribution of the liquid phase, resulting in fine grain size and a uniform, defect-free structure.

[0019] Example 2 Example 2, this embodiment further illustrates Example 1, including the following steps: S1. First, the proportioned ceramic powder, fused white corundum aggregate, fused white corundum fine powder, metallic silicon powder and nitride powder are dried at 150-200℃ for 4 hours to remove adsorbed water. Then, the dried powder and sintering aid are put into a mixer and mixed thoroughly to obtain a primary treatment mixture. S2. Mix water, lubricant and binder evenly first, then slowly add the primary treatment mixture and continue stirring until a uniform slurry is formed to obtain the secondary treatment mixture. Seal the evenly mixed mud and let it stand in a cool environment for 20-32 hours. S3. Place the clay material in a steel mold and press it under an isostatic pressure of 100-120MPa to obtain a green blank with high green body strength. S4. Place the green blank in a nitrogen atmosphere sintering furnace, heat it to 650°C at a rate of 2-4°C / min, hold it for 75 minutes, and pass it through the sintering furnace to completely remove the binder. Then, continue to heat it to 1200-1300°C at a rate of 3-5°C / min, and hold it at this temperature for 2-3 hours to carry out the pre-nitriding reaction. S5. Maintain a nitrogen atmosphere, increase the pressure inside the furnace to 2-10 MPa, and continue to heat to the target sintering temperature of 1580-1680℃ at a rate of 5-8℃ / min, and hold at this temperature for 3-4 hours. S6. After the heat preservation is completed, stop heating and cool the furnace to below 800°C while maintaining nitrogen pressure. Then release the pressure and continue cooling to room temperature. Finally, perform necessary surface grinding and polishing on the sintered body to achieve the required precise dimensions and surface finish, and obtain the final product. S7. Perform density measurement, mechanical property testing and microstructure observation on the finished product to ensure that it meets the performance standards of high-density refractory ceramics. In step S1, the mixing time of the mixer is 40-65 minutes until it is initially uniform. In step S2, sealing and placing it in a cool environment helps to further distribute the moisture evenly, eliminate internal stress, and allow the organic binder to work fully, improving the plasticity of the clay. In step S2, the surface of the metallic silicon powder begins to react with nitrogen to form a Si3N4 layer, forming a preliminary ceramic bonding network, but the reaction is not complete. The sintering aid is one or more of yttrium oxide, calcium oxide, and silicon dioxide. The binder is one or more of polyvinyl alcohol, methylcellulose, or lignin sulfonate. The lubricant is one or more of zinc stearate, calcium stearate, or paraffin wax. The main chemical components of the ceramic powder are alumina and silicon carbide.

[0020] In this embodiment, in-situ nitriding of silicon metal powder is used, which reduces the dependence on high-purity nitride raw materials and is suitable for large-scale production.

[0021] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-density refractory ceramic material, characterized in that, The raw materials include the following parts by weight: 18-24 parts ceramic powder, 15-18 parts fused white corundum aggregate, 12-16 parts fused white corundum fine powder, 9-15 parts metallic silicon powder, 3-5 parts nitride powder, 4-7 parts sintering aid, 1-2 parts lubricant, and 2-4 parts binder.

2. The high-density refractory ceramic material according to claim 1, characterized in that, The raw materials include the following parts by weight: 20 parts ceramic powder, 16 parts fused white corundum aggregate, 14 parts fused white corundum fine powder, 12 parts metallic silicon powder, 4 parts nitride powder, 6 parts sintering aid, 1 part lubricant, and 3 parts binder.

3. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, Includes the following steps: S1. First, the proportioned ceramic powder, fused white corundum aggregate, fused white corundum fine powder, metallic silicon powder and nitride powder are dried at 150-200℃ for 4 hours to remove adsorbed water. Then, the dried powder and sintering aid are put into a mixer and mixed thoroughly to obtain a primary treatment mixture. S2. Mix water, lubricant and binder evenly first, then slowly add the primary treatment mixture and continue stirring until a uniform slurry is formed to obtain the secondary treatment mixture. Seal the evenly mixed mud and let it stand in a cool environment for 20-32 hours. S3. Place the clay material in a steel mold and press it under an isostatic pressure of 100-120MPa to obtain a green blank with high green body strength. S4. Place the green blank in a nitrogen atmosphere sintering furnace, heat it to 650°C at a rate of 2-4°C / min, hold it for 75 minutes, and pass it through the sintering furnace to completely remove the binder. Then, continue to heat it to 1200-1300°C at a rate of 3-5°C / min, and hold it at this temperature for 2-3 hours to carry out the pre-nitriding reaction. S5. Maintain a nitrogen atmosphere, increase the pressure inside the furnace to 2-10 MPa, and continue to heat to the target sintering temperature of 1580-1680℃ at a rate of 5-8℃ / min, and hold at this temperature for 3-4 hours. S6. After the heat preservation is completed, stop heating and cool the furnace to below 800°C while maintaining nitrogen pressure. Then release the pressure and continue cooling to room temperature. Finally, perform necessary surface grinding and polishing on the sintered body to achieve the required precise dimensions and surface finish, and obtain the final product. S7. Perform density measurement, mechanical property testing and microstructure observation on the finished product to ensure that it meets the performance standards of high-density refractory ceramics.

4. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, The mixing time in step S1 is 40-65 minutes until the mixture is initially homogeneous.

5. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, The sealing and stabilization process in step S2 helps to further distribute moisture evenly, eliminate internal stress, and allow the organic binder to work fully, thereby improving the plasticity of the clay.

6. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, In step S2, the surface of the silicon powder begins to react with nitrogen to form a Si3N4 layer, forming a preliminary ceramic bonding network, but the reaction is not complete.

7. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, The sintering aid is one or more of yttrium oxide, calcium oxide, and silicon dioxide.

8. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, The binder is one or more of polyvinyl alcohol, methylcellulose, or lignin sulfonate.

9. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, The lubricant is one or more of zinc stearate, calcium stearate, or paraffin.

10. The high-density refractory ceramic material and its preparation method according to claim 1, characterized in that, The main chemical components of the ceramic powder are alumina and silicon carbide.