Silicon nitride-bonded silicon carbide brick characteristics

Silicon nitride-bonded silicon carbide brick is a new type of high-end refractory material. The raw materials of this brick are of high purity. During the production process, it is also necessary to control the addition of temporary binding agents. The binding agent can help the raw materials to be fused evenly. The binding agent can also improve the reaction efficiency between silicon powder and nitrogen during the drying and firing.

Among nitride-bonded refractory materials, the most widely used material is Si3N4-bonded SiC. Like silicon oxynitride-bonded silicon carbide products and Siallon-bonded silicon carbide products, this material is also used in nitriding furnaces. Obtained by reaction sintering method.

Silicon nitride bonded silicon carbide brick production process

There are two types of processes for silicon nitride combined with silicon carbide bricks: semi-dry molding and grouting molding. Semi-dry molding has higher production efficiency and is currently more common. Grouting molding is relatively rare. Temperature and time during the production process have a great impact on product quality. The temperature cannot be too low and the time cannot be too short. Too low or too short will reduce the nitriding reaction and affect product quality. When the temperature rises too fast or too high, cracks will appear on the surface of the embryo’s body. When installing the kiln, the way the kiln is installed will also affect the quality. There must be a certain space for the smooth penetration of nitrogen, which can avoid silicon flow caused by excessive kiln installation.

The quality and performance of the product are also closely related to the temperature of the nitridation reaction. The firing temperature should be around 1400°C, first the temperature rise stage, and then the nitridation reaction stage of the raw materials. In the heating stage, the temperature rises from the initial temperature to 1100°C, and the temperature of the raw material nitridation reaction is between 1100 and 1350°C.

Characteristics of silicon carbide bonded silicon nitride refractory bricks

Silicon nitride composite bricks have high strength, creep resistance, and nitriding resistance. It is resistant to high temperatures above 1850°C and has the function of not being wetted by metal. It also has good thermal shock resistance at high temperatures and a low thermal expansion coefficient.

Application of silicon nitride composite bricks

Silicon nitride-bonded silicon carbide bricks are mainly used for electrolytic cell linings, ceramic kiln furniture, blast furnace vent water cooling pipe casing bricks, and calcium carbide furnace doors. Not only does it have good energy-saving and environmental protection effects, but its service life is 1-2 times longer than that of silicon carbide bricks.