What is zirconia brick?

What is zirconia brick?

Zirconia bricks are refractory products produced with zirconia as the main raw material. There are two main manufacturing methods: firing method and melting and casting method. There are two crystal forms of zirconia: monoclinic, tetragonal and cubic. When zirconia is heated to about 1100°C, its crystal form will change from monoclinic to tetragonal, accompanied by a volume shrinkage of 7%, and vice versa. Tetragonal zirconia will have a cubic crystal form above 2300°C. The densities of the three crystal forms are 5.68g/cm3 (monoclinic form), 6.10g/cm3 (tetragonal form), and 6.27g/cm3 (cubic form).

Zirconia has a high melting point, high structural strength at high temperatures, and is resistant to acid and alkali erosion. Its physical and chemical properties are as follows:

Apparent porosity%: 15~-20

Volume density (g/cm3): 4.4~-4.6

Normal temperature compressive strength/MPa: 50~-93

Thermal shock resistance (1300℃, water cooling): 6~~12

Zr02+Ca0/%: 97.5

①Dense zirconia bricks

It is formed by isostatic pressing method. Its technical indicators are Zr02>65%, apparent porosity <2.0%, and volume density of about 4.25g/cm3. In E glass, there will be corrosion when the temperature exceeds 1370°C. It is used in the bottom of the melting part of the E glass unit kiln where the temperature of the molten glass is slightly lower, the bottom of the transition channel, the bottom of the forming channel, the liquid tank of the forming channel and the leaky plate support brick, etc. In addition, dense zirconium bricks are also used as backing bricks for dense chrome bricks;

Commonly used international brands include ZS-1300, ZS-1500, ZS-835 and ZS-78 produced by the American CORHART company, ZS65WA produced by the German VGT-DYKO company, and UC-Z, UC-CZ, and UC produced by the Japanese Shinagawa Co., Ltd. -CZB et al.

In recent years, our country's refractory material companies have introduced foreign technology and equipment, and have also produced sintered dense zirconium bricks formed by isostatic pressing, which have been used in some domestic glass and fiberglass kilns.

The German VGT-DYKO company has developed a new type of coarse-grained dense zirconia brick, which greatly improves the internal structure of the brick, thereby improving the brick's resistance to rapid cooling and heat. Its volume density is 3.75a/cm3, and its porosity is 17%. The brand name of this brick is ZS65AR, which has good thermal shock resistance and is most suitable for drawing flow channels and leaky plate support bricks.

②Standard zirconium brick

The ZrO2 content of this brick is about 66%, the bulk density is 3.7a/cm3, and it has good thermal stability and peeling resistance. It is used on the breast wall and back wall of the feeding port area where the powder erosion is serious, the furnace observation hole brick and the breast wall and roof brick of the flame space, and the burner brick.