Characteristics and application scope of silicon nitride bonded silicon carbide bricks

Silicon nitride bonded silicon carbide bricks, as an advanced refractory material, have shown extraordinary application value in many industrial fields with their unique physical and chemical properties. This article will conduct an in-depth discussion from three aspects: its characteristics, preparation process and wide range of applications.

Characteristics of silicon nitride bonded silicon carbide bricks

Silicon Nitride Bonded Silicon Carbide Brick (SNBSC) is known for its excellent performance, which mainly includes the following aspects:

1. High high-temperature strength: Silicon nitride combined with silicon carbide bricks exhibit extremely high strength in high-temperature environments, and their high-temperature flexural strength is 4 to 8 times that of ordinary refractory materials. Even at high temperatures of 1200 to 1400°C, its strength and hardness remain almost the same as at normal temperature, making it an indispensable material in high-temperature industrial fields.

2. High thermal conductivity: The thermal conductivity of this material is 7 to 8 times that of ordinary refractory materials. The excellent thermal conductivity helps to quickly balance the temperature distribution, reduce thermal stress, and improve the stability and service life of the equipment.

3. Good thermal shock stability: Silicon nitride combined with silicon carbide bricks have a small thermal expansion coefficient, high thermal conductivity, and are not prone to thermal stress, so they have excellent thermal shock resistance. The structural integrity and stability can still be maintained in environments with rapid changes in high temperature.

4. Excellent corrosion resistance: This material has excellent corrosion resistance to a variety of chemical substances, such as cryolite, aluminum fluoride, sodium fluoride, calcium fluoride and other molten substances, which makes it suitable for use in harsh environments such as non-ferrous metal smelting. Excellent performance in the environment.

5. Strong oxidation resistance: Silicon nitride and silicon carbide are both strong oxidation resistance materials. Even in high-temperature oxidizing atmospheres, they can maintain good stability and are not easily oxidized.

6. High hardness and high wear resistance: The Mohs hardness of silicon nitride combined with silicon carbide bricks is about 9, which belongs to the high hardness category among non-metallic materials. Its wear resistance is also extremely excellent, and it is suitable for use in high-wear environments. application.

Preparation process

The preparation process of silicon nitride bonded silicon carbide bricks is complex and delicate, and the reaction sintering method is mainly used. Silicon carbide sand is used as the main raw material, an appropriate amount of metallic silicon powder is added, and the green body is prepared through reasonable particle gradation, mixing system and molding process. Subsequently, high-temperature firing is performed in a dedicated firing equipment under a nitrogen atmosphere. During the firing process, metallic silicon powder reacts with nitrogen to generate silicon nitride (Si3N4). This gray-white crystal serves as the matrix binding phase, tightly binding the silicon carbide particles (aggregate) together to form a spatial network structure, giving the material a unique performance.

Application scope

Silicon nitride bonded silicon carbide bricks are widely used in many industrial fields due to their excellent properties:

1. Non-ferrous metal smelting: In the smelting process of aluminum, lead, zinc, copper and other metals, silicon nitride combined with silicon carbide bricks are used as electrolytic cell linings, nozzle bricks, waist and belly bricks, etc., which are not only resistant to erosion and erosion, but also It can also maintain good thermal conductivity and improve smelting efficiency.

2. Steel industry: In the steelmaking and steel rolling processes, silicon nitride combined with silicon carbide materials are used as ladle linings, blast furnace tuyere bricks, etc. Its high-temperature strength and thermal shock resistance significantly improve the service life and safety of the equipment. sex.

3. Ceramics and electric porcelain: During the firing process of ceramics and electric porcelain, kiln furniture and rollers made of silicon nitride combined with silicon carbide significantly reduce energy consumption and improve product quality and qualification rate.

4. Metal heat treatment: In the field of metal heat treatment, silicon nitride combined with silicon carbide materials can be used to make fixtures, heating elements and other components. Its high temperature resistance and thermal shock resistance ensure the stability and efficiency of the heat treatment process.

5. Environmental protection industry: In desulfurization and denitrification projects, nozzles made of silicon nitride combined with silicon carbide materials have the advantages of precise size, corrosion resistance, erosion resistance, and excellent atomization performance, which significantly improve the operating efficiency and lifespan of environmental protection equipment.

6. Other industrial fields: In addition, silicon nitride combined with silicon carbide materials are also widely used in submerged arc furnaces, thermal power plants, industrial kilns, powder processing, wear-resistant current components and other fields. Its high-performance characteristics are ideal for these industries. Provide strong support for equipment upgrades and energy conservation and emission reduction.

In summary, silicon nitride bonded silicon carbide bricks play an increasingly important role in modern industry due to their excellent performance and wide range of applications. With the continuous advancement of science and technology and the growing industrial demand, the application prospects of silicon nitride combined with silicon carbide materials will be broader.