Preparation of nitride-bonded corundum-silicon carbide composite

Abstract

This invention relates to the field of refractory material production technology, specifically to the preparation of nitride-bonded corundum-silicon carbide composite materials. The mixture comprises 50-80 wt% silicon carbide particles, 5-20 wt% corundum particles, 5-20 wt% silicon powder, 2-12 wt% silica micropowder, 2-5 wt% additives, and 1-2 wt% water or alcohol. The corundum particles consist of two different particle sizes: 0-1 mm and 1-3 mm, with contents of 3-8 wt% and 5-15 wt%, respectively. The silicon carbide particles consist of three different particle sizes: 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm, with contents of 10-15 wt%, 25-35 wt%, and 10-15 wt%, respectively. A fine mixed powder is obtained by mixing the silica micropowder, silicon powder, and silica powder. The mixture is then loaded into a mold and formed by friction vibration. After drying, it undergoes nitriding treatment. The silica powder and silica micropowder in the blank undergo a co-nitriding reaction to generate silicon nitride and silicon oxynitride. The mixture is then cooled to room temperature in a furnace to obtain a nitride-bonded corundum-silicon carbide composite material. The process is simple and the production cost is low. Its products have excellent high temperature resistance and thermal shock resistance, which are significantly better than those of traditional silicon nitride-bonded silicon carbide materials.

Description

Technical Field

[0001] This invention belongs to the field of refractory material preparation technology, specifically relating to the preparation of a nitride-bonded corundum-silicon carbide composite material. Background Technology

[0002] Pusher kilns are widely used in the ceramics and refractory materials industries. The performance of the pusher plates typically determines the kiln's operating efficiency. During operation, pusher plates must withstand the loads of ceramic blanks or saggers, enormous top forces, and frictional resistance with the tracks at high temperatures without breaking. Their service life must be as high as dozens or even hundreds of cycles. Therefore, pusher plates are required to have excellent high-temperature resistance, high mechanical strength, good wear resistance, good thermal shock resistance, and volume stability. They must also be non-contaminated to sintering elements and have good chemical resistance. Currently, silicon carbide is commonly used for pusher plates both domestically and internationally. While corundum-mullite and silicon carbide pusher plates are primarily composed of silicon oxide bonded to silicon carbide, they are prone to cracking after repeated use, limiting their application to low-end manufacturing sectors. Traditional refractory materials like corundum and mullite offer numerous advantages, such as high load softening temperatures and good creep resistance, but their strength is not ideal, and their high cost hinders economic viability and market competitiveness. Pusher plates made from silicon nitride-bonded silicon carbide materials exhibit excellent thermodynamic properties: high high-temperature strength, good thermal conductivity, low coefficient of thermal expansion, and resistance to acid and alkali corrosion; however, their thermal shock resistance needs further improvement. Therefore, developing advanced formulations and processes to prepare novel refractory materials with high thermal shock resistance is crucial for extending the service life and ensuring the operational safety of pusher kilns. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a nitride-bonded corundum-silicon carbide ceramic composite material.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a nitride-bonded corundum-silicon carbide composite material, comprising the following raw materials by mass percentage: 50-80 wt% silicon carbide particles, 5-20 wt% corundum particles, 5-20 wt% silicon powder, 2-12 wt% silica micropowder, 2-5 wt% additives, and 1-2 wt% water or alcohol; wherein the corundum particles consist of two different particle sizes, 0-1 mm and 1-3 mm, with contents of 3-8 wt% and 5-15 wt%, respectively; the silicon carbide particles consist of three different particle sizes, 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm, with contents of 10-15 wt%, 25-35 wt%, and 10-15 wt%, respectively; the silica micropowder, silicon powder, and silica powder are mixed to obtain a fine powder; and a binder is mixed with water or alcohol. A mixture is formed; silicon carbide particles and corundum particles are mixed and then uniformly mixed with the mixture to form a uniform film on the particle surface; the mixed fine powder is mixed with the mixed particles uniformly covered with the film to obtain a mixture; the mixture is placed in a vibration molding machine for molding to obtain a green body; after drying the obtained green body, it is placed in a nitriding sintering furnace for nitriding treatment, where the silicon powder and silica micro powder in the green body undergo a nitriding reaction to generate silicon nitride and silicon oxynitride; finally, it is cooled to room temperature with the furnace to prepare a nitride-bonded corundum-silicon carbide composite material.

[0006] The corundum particles are one of lightweight corundum, plate corundum, or a mixture of both.

[0007] The silicon carbide micro powder D 50 ≤10μm, content is 5-15wt%.

[0008] The silicon powder D 50 ≤10μm, content is 5-20wt%.

[0009] The D of the silica micro powder 50 ≤10μm, content is 2-12wt%.

[0010] The additive is one or more of calcium lignosulfonate, dextrin, phenolic resin, and water-soluble resin, with a content of 2-5 wt%.

[0011] The preparation method of the nitride-bonded corundum-silicon carbide composite material proposed in this invention has the following beneficial effects:

[0012] Alumina, being an oxide, possesses excellent oxidation resistance. Its coefficient of thermal expansion is significantly different from that of silicon carbide. Introducing the corundum phase during the preparation of silicon nitride-bonded silicon carbide materials helps to pre-establish cracks within the material, thereby improving its thermal shock resistance. Therefore, using silicon carbide, corundum, silicon powder, and silica micropowder as main raw materials, silicon powder and silica micropowder undergo a co-nitridation reaction to generate silicon nitride and silicon oxynitride, resulting in a nitride-bonded corundum-silicon carbide composite material. This production process is simple, and the resulting product maintains the high-temperature flexural strength of silicon nitride-bonded silicon carbide materials while improving their thermal shock resistance, thus possessing broad economic and social value. The bulk density of this product is 2.67-2.73 g / cm³. 3 With a porosity of 14%-15%, a room temperature compressive strength of 180-200MPa, and a high temperature flexural strength of 40-50MPa, the prepared nitride-bonded corundum-silicon carbide composite material retains 320% of its thermal shock resistance after 5 water-cooling cycles at 1350℃, exhibiting performance superior to traditional silicon nitride-bonded silicon carbide refractory materials. Detailed Implementation

[0013] The present invention will be further described below with reference to specific embodiments: Example 1

[0014] The following mixed raw materials were weighed according to mass percentage: silicon carbide particles with particle sizes of 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm were weighed at 15 wt%, 35 wt%, and 15 wt%, respectively; lightweight corundum particles with particle sizes of 0-1 mm and 1-3 mm were weighed at 3 wt% and 5 wt%, respectively; silicon carbide micro powder, silicon powder, and silica powder were weighed at 10 wt%, 12 wt%, and 5 wt%, respectively; and a mixture of calcium lignosulfonate and water was added, with mass percentages of 2 wt% and 1 wt% of the total mass of the mixed raw materials, respectively. The mixture was loaded into a mold and vibrated to form the final product. After drying, it was placed in a nitriding sintering furnace for nitriding treatment at 1420℃. Finally, it was cooled to room temperature with the furnace to prepare a nitride-bonded corundum-silicon carbide composite material. The performance index of the nitride-bonded corundum-silicon carbide ceramic composite material prepared in this embodiment was tested and found to be: bulk density 2.70 g / cm³. 3 The porosity is 15%, the compressive strength at room temperature is 202 MPa, the flexural strength at high temperature is 46 MPa, and the composite material retains 30% of its thermal shock after 5 water-cooling cycles at 1350℃. Example 2

[0015] The following raw materials were weighed by mass percentage: silicon carbide particles with particle sizes of 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm were weighed at 15 wt%, 30 wt%, and 15 wt%, respectively; lightweight corundum particles with particle sizes of 0-1 mm and 1-3 mm were weighed at 3 wt% and 10 wt%, respectively; silicon carbide micro powder, silicon powder, and silica powder were weighed at 10 wt%, 12 wt%, and 5 wt%, respectively; and a mixture of calcium lignosulfonate and water was added, with the mass percentages being 2 wt% and 1 wt% of the total mass of the raw materials, respectively. The mixture was loaded into a mold and vibrated to form the final product. After drying, it was placed in a nitriding sintering furnace for nitriding treatment at 1420℃. Finally, it was cooled to room temperature with the furnace to prepare a nitride-bonded corundum-silicon carbide composite material. The performance index of the nitride-bonded corundum-silicon carbide ceramic composite material prepared in this embodiment was tested and found to be: bulk density 2.71 g / cm³. 3 The porosity is 14.5%, the compressive strength at room temperature is 194 MPa, the flexural strength at high temperature is 42 MPa, and the composite material retains 325% of its thermal shock after 5 water-cooling cycles at 1350℃. Example 3

[0016] The following mixed raw materials were weighed according to mass percentage: silicon carbide particles with particle sizes of 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm were weighed at 15 wt%, 30 wt%, and 15 wt%, respectively; lightweight corundum particles with a particle size of 1-3 mm were weighed at 10 wt%; tabular corundum particles with a particle size of 0-0.5 mm were weighed at 3 wt%; and silicon carbide micro powder, silicon powder, and silica powder were weighed at 10 wt%, 12 wt%, and 5 wt%, respectively. A mixture of resin and alcohol was added, with mass percentages of 5 wt% and 1 wt% of the total mass of the mixed raw materials, respectively. The mixture was loaded into a mold and vibrated to form the final product. After drying, it was placed in a nitriding sintering furnace for nitriding treatment at 1420℃. Finally, it was cooled to room temperature with the furnace to prepare a nitride-bonded corundum-silicon carbide composite material. The performance indicators of the nitride-bonded corundum-silicon carbide ceramic composite material prepared in this embodiment were tested, and the bulk density was 2.71 g / cm³. 3 The porosity is 14.5%, the compressive strength at room temperature is 194 MPa, the flexural strength at high temperature is 46 MPa, and the composite material retains 320% of its thermal shock resistance after 5 water-cooling cycles at 1350℃. Example 4

[0017] The following raw materials were weighed according to mass percentage: silicon carbide particles with particle sizes of 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm were weighed at 15 wt%, 30 wt%, and 15 wt%, respectively; tabular corundum particles with a particle size of 1-3 mm were weighed at 10 wt%; lightweight corundum particles with a particle size of 0-0.5 mm were weighed at 3 wt%; and silicon carbide micro powder, silicon powder, and silica powder were weighed at 10 wt%, 12 wt%, and 5 wt%, respectively. A mixture of resin and alcohol was added, with mass percentages of 5 wt% and 1 wt% of the total mass of the raw materials, respectively. The mixture was loaded into a mold and vibrated to form the final product. After drying, it was placed in a nitriding sintering furnace for nitriding treatment at 1420℃. Finally, it was cooled to room temperature with the furnace to prepare a nitride-bonded corundum-silicon carbide composite material. The performance indicators of the nitride-bonded corundum-silicon carbide ceramic composite material prepared in this embodiment were tested, and the bulk density was 2.72 g / cm³. 3 The porosity is 14.2%, the room temperature compressive strength is 188MPa, the high temperature flexural strength is 41MPa, and the composite material retains 320% of its thermal shock resistance after 5 water-cooling cycles at 1350℃.

Claims

1. A method for preparing a nitride-bonded corundum-silicon carbide composite material, characterized in that: The nitride-bonded corundum-silicon carbide composite material is composed of the following raw materials in the indicated weight percentages: 50-80 wt% silicon carbide particles, 5-20 wt% corundum particles, 5-20 wt% silicon powder, 2-12 wt% silica micropowder, 5-15 wt% silicon carbide micropowder, 2-5 wt% additives, and 1-2 wt% water or alcohol. The corundum particles consist of two different particle sizes: 0-1 mm and 1-3 mm, with contents of 3-8 wt% and 5-15 wt%, respectively. The silicon carbide particles consist of three different particle sizes: 1.5-2.5 mm, 0.5-1.5 mm, and 0-0.5 mm, with contents of 10-15 wt%, 25-35 wt%, and 10-15 wt%, respectively. The silica micropowder, silicon powder, and silica powder are mixed to obtain a fine powder. The additives include calcium lignosulfonate, dextrin, phenolic resin, and water-soluble resin. One or more of the following: The additive is mixed with water or alcohol to form a mixture; silicon carbide particles and corundum particles are mixed and then uniformly mixed with the mixture to form a uniform film on the particle surface; the fine powder is mixed with the uniformly film-covered particles to obtain a mixture; the mixture is placed in a vibration molding machine for molding to obtain a green body; the obtained green body is dried and placed in a nitriding sintering furnace for nitriding treatment, where the silicon powder and silica micropowder in the green body undergo a nitriding reaction to generate silicon nitride and silicon oxynitride; finally, the mixture is cooled to room temperature with the furnace to prepare a nitride-bonded corundum-silicon carbide composite material.

2. The production of a nitride-bonded corundum-silicon carbide composite material as claimed in claim 1, characterized in that The corundum particles are one of lightweight corundum, plate corundum, or a mixture of both.

3. The preparation of a nitride-bonded corundum-silicon carbide composite material as described in claim 1, characterized in that: The D of the silicon carbide micro powder 50 ≤10μm.

4. The preparation of a nitride-bonded corundum-silicon carbide composite material as described in claim 1, characterized in that: The silicon powder D 50 ≤10μm.

5. The preparation of a nitride-bonded corundum-silicon carbide composite material as described in claim 1, characterized in that: The D of the silica micro powder 50 ≤10μm.