Clay bonded products are widely used in silicon carbide refractories

Due to the different silicon carbide bonding materials, their properties, service conditions and service life are very different

Silicon carbide refractory is a high-quality refractory with excellent high-temperature properties such as high strength, high thermal conductivity, good seismic resistance, oxidation resistance, wear resistance and corrosion resistance. It is widely used in metallurgy, energy, chemical industry and other industries.

At first, silicon carbide refractories used clay, SiO2, silicate and mullite as binder. With the application of high-tech means, new silicon carbide products have been widely developed. Such as silicon nitride bonded silicon carbide, silicon oxynitride bonded silicon carbide, reaction sintered silicon carbide, recrystallized silicon carbide from recrystallized raw materials, silicon carburizing silicon carbide and other silicon carbide materials. Their high temperature performance is more excellent, so that silicon carbide refractories continue to enter new application fields.

Various types of silicon carbide refractories are introduced as follows:

Silicon carbide refractories with different bonding phases

1. Clay bound phase

In silicon carbide refractories, clay bonded products are common, low price and simple process. At present, clay bonded silicon carbide kiln has a large amount in China's ceramic industry.

Due to the reaction of aluminum, oxygen and silicon carbide in clay at 1120 ~ 1150 ℃, the product has low fire resistance and weak oxidation resistance, and its application field is limited. The amount of clay in the product generally does not exceed 15%, and the amount of fine powder in the ingredients should not be too large, otherwise it is easy to oxidize. The content of silicon carbide is between 50% ~ 93%. It is generally used to make sagger, cushion cake and flame barrier plate.

2. SiO2 binding phase

About 10% SiO2 (micro powder and quartz powder) is added to silicon carbide, and SiO2 film is formed on the surface of silicon carbide particles by means of sintering process to combine silicon carbide particles. Because of its high purity of raw materials and less impurities, its high-temperature performance is much better than that of clay bonded products, but the performance of the product is also affected by the molding process. It can be used in high oxygen atmosphere above 1200 ℃. It is generally used to make shed plates and pillars.

3. Mullite bonded silicon carbide

Mullite (5% ~ 8%) and silicon carbide are used as raw materials and pulp or dextrin as binder. After molding, mullite and silicon carbide are sintered at 1380 ℃. Compared with clay bonded silicon carbide and SiO2 bonded silicon carbide, the product has excellent performance, thermal shock resistance and oxidation resistance. At present, it is gradually used in ceramic kilns in China.