CN104860691A - Preparation method for high-strength ferro silicon nitride kiln furniture - Google Patents

Abstract

The invention belongs to the field of high-grade refractory materials, and relates to a preparation method of auxiliary materials in the firing process of ceramic materials and magnetic materials, in particular to a preparation method of high-strength ferrosilicon nitride kiln furniture, using iron-silicon 75 alloy powder as raw material, Nitriding combustion in the nitriding furnace can obtain a honeycomb loose block ferrosilicon nitride raw body, after cutting, impregnating with phenolic resin, drying and grinding, the finished ferrosilicon nitride kiln furniture can be obtained, and the kiln furniture The normal temperature compressive strength of the finished product is greater than 90MPa. The beneficial effect of the present invention is: the preparation method breaks through the traditional kiln furniture preparation method, the kiln furniture does not need to be formed, does not need to be sintered at high temperature, the production process is simple, and the ferrosilicon nitride kiln furniture prepared by this method can be used repeatedly, and the number of times of use is more than 200 Second, it greatly saves energy and production costs, and is convenient for industrial promotion and application.

Description

Preparation method of high-strength silicon nitride iron kiln furniture

technical field

The invention belongs to the field of high-grade refractory materials, and relates to a preparation method of auxiliary materials for firing ceramic materials and magnetic materials, in particular to a preparation method of high-strength ferrosilicon nitride kiln furniture.

Background technique

Kiln furniture is an important auxiliary material in ceramic materials and magnetic materials, which plays a supporting and protective role in the sintering process of materials. On the one hand, the kiln furniture should protect the fired products from pollution and erosion such as gas and dust; on the other hand, the kiln furniture plays the role of holding and supporting. Therefore, the kiln furniture must not only bear the weight of the fired product, but also avoid chemical reaction with the product to cause pollution. The kiln furniture is required to have the following basic properties: (1) High fire resistance, good thermal stability and chemical stability; (2) High normal temperature and high temperature compressive strength; (3) Good thermal conductivity, low heat storage; (4) Regular appearance and precise size.

With the development of the ceramic industry, higher requirements are put forward for kiln furniture, and the firing of traditional products is transformed from sagger firing to open flame boxless firing; kiln furniture materials are moving toward high strength, thin wall, light weight, energy It is developed in the direction of rapid high-temperature firing, higher regularity and precision.

At present, kiln furniture at home and abroad can be mainly divided into three major systems: magnesium aluminum silicon kiln furniture, silicon carbide kiln furniture and new kiln furniture. At present, among domestically used kiln furniture, high-alumina kiln furniture has low strength, poor thermal stability, and short service life; mullite kiln furniture has high cost, which is not conducive to large-scale industrialization; Fe ₂ O ₃ , the performance is affected, and high pressure is required for molding, which is difficult to achieve with general equipment, and the production cost is high. Compared with foreign countries, there is still a certain gap in the development level of domestic kiln furniture. The low performance of kiln furniture has seriously hindered the renewal and development of the ceramic industry. Therefore, selecting high-quality and cheap raw materials and adopting a simple process to prepare kiln furniture materials with excellent and stable performance, high regularity and precision, and to promote large-scale industrialization to alleviate the situation that SiC kiln furniture is difficult to use in large quantities. with a direction of development.

The high-strength ferrosilicon nitride kiln furniture of the present invention has relatively high strength and can meet the requirements of support and load-bearing of the kiln furniture; the porosity is relatively high, and it is a kind of porous ceramic with good thermal shock stability; The main phase of ferrosilicon nitride is silicon nitride, and the service temperature is relatively high; under the conditions of use of ferrosilicon nitride, no melt and gas phase will be produced, and it has good chemical stability; only by cutting the original billet of ferrosilicon nitride The kiln furniture can be prepared from the body, the processing technology is simple, the cost is extremely low, and it is convenient for industrialization and large-scale application; ferrosilicon nitride is a kind of honeycomb porous ceramic, which is easy to cut and meets the requirements of kiln furniture for regularity and accuracy. . Therefore, the high-strength ferrosilicon nitride kiln furniture described in the present invention can meet the requirements of the ceramic industry under the new situation for kiln furniture materials to be high-strength, thin-walled and light, able to withstand rapid high-temperature firing, and have higher regularity and accuracy. direction of development needs.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention provides a method for preparing high-strength ferrosilicon nitride kiln furniture that can be used in the sintering process of ceramic materials and magnetic materials.

The technical scheme of the present invention is: the preparation method of high-strength ferrosilicon nitride kiln furniture, this method specifically comprises the following steps:

Step 1. Preparation of block: Using iron-silicon 75 alloy powder as raw material, nitriding and burning in a flash nitriding furnace to obtain a honeycomb loose block ferrosilicon nitride original body, the ferrosilicon nitride The phases of the original green body are Fe ₃ Si and Si ₃ N ₄ , the mass fraction of Fe ₃ Si is 20%-30%, the mass fraction of silicon nitride is 70%-80%, and the apparent porosity is 20%-40%; The bulk density is 2.4-2.7g/cm ³ ;

Step 2. Cutting: cutting the ferrosilicon nitride body obtained in step 1 according to the production requirements of kiln furniture to obtain kiln furniture of the desired shape;

Step 3. Put the kiln furniture prepared in step 2 into a vacuum tank, evacuate to 10 ^-1 ~10 ^-3 MPa, heat the phenolic resin with a carbon residue rate ≥ 50% to 150-250°C, and heat the heated phenolic resin Put the resin into the device connected with the vacuum tank, open the valve between the vacuum tank and the device, fill the vacuum tank with kiln furniture with phenolic resin, pressurize to 5~10MPa, and make the ferrosilicon nitride kiln furniture in the phenolic Immerse in resin for 5-10 h;

Step 4. Drying: Put the kiln furniture into a drying box after being processed in step 3, and dry it for 20-24 hours at a temperature of 200°C;

Step 5. Polish the dried ferrosilicon nitride kiln furniture until it is smooth, and then the finished ferrosilicon nitride kiln furniture can be obtained, and the normal temperature compressive strength of the finished kiln furniture is greater than 90MPa.

Further, the vacuum tank can withstand a pressure above 15MPa.

In the present invention, phenolic resin is added, and the phenolic resin decomposes at high temperature, leaving a certain amount of residual carbon in the ferrosilicon nitride kiln furniture. Carbon reacts with silicon nitride in ferrosilicon nitride at high temperature, forming silicon carbide during use under high temperature and harsh conditions, forming a silicon nitride combined with silicon nitride structure, which has better high temperature performance and can improve structural stability . Adding phenolic resin can close some pores in the ferrosilicon nitride kiln furniture, and the reduction rate can reach 30% of the original porosity. The residual carbon left after the resin on the surface of silicon nitride kiln furniture is decomposed can reduce the wetting angle with the sample, so that the product will not react with the kiln furniture.

The beneficial effects of the present invention are: due to the adoption of the above technical scheme, the method can obtain high-strength ferrosilicon nitride kiln furniture by cutting it into different sizes according to the actual production requirements of different types of kiln furniture. And the preparation method breaks through the traditional kiln furniture preparation method. The kiln furniture does not need molding, heat treatment, and high-temperature sintering. The production process is simple. The ferrosilicon nitride kiln furniture prepared by this method can be used repeatedly. Significantly save energy and production costs.

detailed description

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

The preparation method of high-strength silicon nitride iron kiln furniture of the present invention, this method specifically comprises the following steps:

Step 1. Preparation of block: Using iron-silicon 75 alloy powder as raw material, nitriding and burning in a flash nitriding furnace to obtain a honeycomb loose block ferrosilicon nitride original body, the ferrosilicon nitride The phases of the original green body are Fe ₃ Si and Si ₃ N ₄ , the mass fraction of Fe ₃ Si is 20%-30%, the mass fraction of silicon nitride is 70%-80%, and the apparent porosity is 20%-40%; The bulk density is 2.4-2.7g/cm ³ ;

Step 2. Cutting: cutting the ferrosilicon nitride body obtained in step 1 according to the production requirements of kiln furniture to obtain kiln furniture of the required shape;

Step 3. Put the kiln furniture prepared in step 2 into a vacuum tank, evacuate to 10 ^-1 ~10 ^-3 MPa, heat the phenolic resin with a carbon residue rate ≥ 50% to 150-250°C, and heat the heated phenolic resin Put the resin into the device connected with the vacuum tank, open the valve between the vacuum tank and the device, fill the vacuum tank with kiln furniture with phenolic resin, pressurize to 5~10MPa, and make the ferrosilicon nitride kiln furniture in the phenolic Immerse in resin for 5-10 h;

Step 4. Drying: Put the kiln furniture into a drying box after being processed in step 3, and dry it for 20-24 hours at a temperature of 200°C;

Step 5. Polish the dried ferrosilicon nitride kiln furniture until it is smooth, and then the finished ferrosilicon nitride kiln furniture can be obtained, and the normal temperature compressive strength of the finished kiln furniture is greater than 90MPa.

Example 1:

A method for preparing high-strength ferrosilicon nitride kiln furniture, the method specifically includes the following steps:

Step 1. Preparation of block: Using iron-silicon 75 alloy powder as raw material, nitriding and burning in a flash nitriding furnace to obtain a honeycomb loose block ferrosilicon nitride original body, the ferrosilicon nitride The phases of the original green body are Fe ₃ Si and Si ₃ N ₄ , the mass fraction of Fe ₃ Si is 25%, the mass fraction of silicon nitride is 75%, the apparent porosity is 30%; the bulk density is 2.5g/cm ³ ;

Step 2. Cutting: cutting the ferrosilicon nitride body obtained in step 1 according to the production requirements of kiln furniture to obtain kiln furniture of the desired shape;

Step 3. Put the kiln furniture prepared in step 2 into a vacuum tank, evacuate to 10 ^-2 MPa, heat the phenolic resin with a carbon residue rate ≥ 50% to 250°C, and put the heated phenolic resin into the vacuum tank In the connected device, open the valve between the vacuum tank and the device, fill the vacuum tank with kiln furniture with phenolic resin, pressurize to 7.5MPa, and impregnate the silicon nitride kiln furniture in the phenolic resin for 45 minutes;

Step 4. Drying: put the kiln furniture into a drying box after being processed in step 3, and dry it for 24 hours at a temperature of 200°C;

Step 5. Polish the dried ferrosilicon nitride kiln furniture until it is smooth, and then the finished ferrosilicon nitride kiln furniture can be obtained, and the normal temperature compressive strength of the finished kiln furniture is greater than 90MPa.

Example 2:

A method for preparing high-strength ferrosilicon nitride kiln furniture, the method specifically includes the following steps:

Step 1. Preparation of block: Using iron-silicon 75 alloy powder as raw material, nitriding and burning in a flash nitriding furnace to obtain a honeycomb loose block ferrosilicon nitride original body, the ferrosilicon nitride The phases of the original green body are Fe ₃ Si and Si ₃ N ₄ , the mass fraction of Fe ₃ Si is 30%, the mass fraction of silicon nitride is 70%, the apparent porosity is 40%; the bulk density is 2.7g/cm ³ ;

Step 2. Cutting: cutting the ferrosilicon nitride body obtained in step 1 according to the production requirements of kiln furniture to obtain kiln furniture of the desired shape;

Step 3. Put the kiln furniture prepared in step 2 into a vacuum tank, evacuate to 10 ^-3 MPa, heat the phenolic resin with a carbon residue rate ≥ 50% to 200°C, and put the heated phenolic resin into the vacuum tank In the connected device, open the valve between the vacuum tank and the device, fill the vacuum tank with kiln furniture with phenolic resin, pressurize to 10MPa, and impregnate the iron silicon nitride kiln furniture in the phenolic resin for 1 hour;

Step 4. Drying: Put the kiln furniture into a drying box after being processed in step 3, and dry it for 22 hours at a temperature of 200°C;

Step 5. Polish the dried ferrosilicon nitride kiln furniture until it is smooth, and then the finished ferrosilicon nitride kiln furniture can be obtained, and the normal temperature compressive strength of the finished kiln furniture is greater than 90MPa.

Example 3:

A method for preparing high-strength ferrosilicon nitride kiln furniture, the method specifically includes the following steps:

Step 1. Preparation of block: Using iron-silicon 75 alloy powder as raw material, nitriding and burning in a flash nitriding furnace to obtain a honeycomb loose block ferrosilicon nitride original body, the ferrosilicon nitride The phases of the original green body are Fe ₃ Si and Si ₃ N ₄ , the mass fraction of Fe ₃ Si is 20%, the mass fraction of silicon nitride is 80%, the apparent porosity is 25%; the bulk density is 2.4cm ³ ;

Step 2. Cutting: cutting the ferrosilicon nitride body obtained in step 1 according to the production requirements of kiln furniture to obtain kiln furniture of the desired shape;

Step 3. Put the kiln furniture prepared in step 2 into a vacuum tank, evacuate to 10 ^-1 MPa, heat the phenolic resin with a carbon residue rate ≥ 50% to 150°C, and put the heated phenolic resin into the vacuum tank In the connected device, open the valve between the vacuum tank and the device, fill the vacuum tank with kiln furniture with phenolic resin, pressurize to 5MPa, and impregnate the iron silicon nitride kiln furniture in the phenolic resin for 0.5 h;

Step 4. Drying: Put the kiln furniture into a drying box after being processed in step 3, and dry for 20 hours at a temperature of 200° C.;

Step 5. Polish the dried ferrosilicon nitride kiln furniture until it is smooth, and then the finished ferrosilicon nitride kiln furniture can be obtained, and the normal temperature compressive strength of the finished kiln furniture is greater than 90MPa.

Claims (2)

1. The preparation method of high-strength ferrosilicon nitride kiln furniture is characterized in that, the method specifically comprises the following steps: Step 1. Preparation of block: Using iron-silicon 75 alloy powder as raw material, nitriding and burning in a flash nitriding furnace to obtain a honeycomb loose block ferrosilicon nitride original body, the ferrosilicon nitride The phases of the original green body are Fe ₃ Si and Si ₃ N ₄ , the mass fraction of Fe ₃ Si is 20%-30%, the mass fraction of silicon nitride is 70%-80%, and the apparent porosity is 20%-40%; The bulk density is 2.4-2.7g/cm ³ ; Step 2. Cutting: cutting the ferrosilicon nitride body obtained in step 1 according to the production requirements of kiln furniture to obtain kiln furniture of the required shape; Step 3. Put the kiln furniture prepared in step 2 into a vacuum tank, evacuate to 10 ^-1 -10 ^-3 MPa, heat the phenolic resin with a carbon residue rate ≥ 50% to 150-250°C, and heat the heated phenolic resin Put the resin into the device connected with the vacuum tank, open the valve between the vacuum tank and the device, fill the vacuum tank with kiln furniture with phenolic resin, pressurize to 5~10MPa, and make the ferrosilicon nitride kiln furniture in the phenolic Immerse in resin for 5-10 h; Step 4. Drying: Put the kiln furniture into a drying box after being processed in step 3, and dry it for 20-24 hours at a temperature of 200°C; Step 5. Polish the dried ferrosilicon nitride kiln furniture until it is smooth, and then the finished ferrosilicon nitride kiln furniture can be obtained, and the normal temperature compressive strength of the finished kiln furniture is greater than 90MPa. 2. The method according to claim 1, characterized in that the vacuum tank can withstand a pressure above 15MPa.