Properties and applications of fused cast AZS

Fused cast AZS block is the most widely used fused cast refractory brick. According to the ZrO2 content, it can be divided into 33#, 36# and 41#AZS.
Fused cast AZS containing 33% ZrO2 is called 33# fused cast AZS; fused cast AZS containing 36% ZrO2 is called 36# fused cast AZS; fused cast AZS containing 41% ZrO2 is called 41# fused cast AZS.
Fused cast AZS is mainly composed of baddeleyite and corundum and their eutectic crystals. High viscosity glass phase is filled in the gaps of crystals. The crystals is directly precipitated from the molten liquid and well developed. So, it has large crystal particles and stable crystal phase. Except the voids, it has compact structure and better density than the common sintered bricks. The pores are mainly closed pores and the crystals are intertwined each other, so it has good mechanical properties and wear resistance. The impurities are difficult to invade the bricks. Therefore, this refractory brick has good corrosion resistance. besides, the transformation of ZrO2 at 900~1150℃ when heating or cooling may cause irregular deformation.
Fused cast AZS block can be used in areas in direct contact with molten metals and molten slags. It is the essential material used in the key areas that suffer from severe corrosion.

How to Store Ceramic Fiber Board

Ceramic fiber board is a high-strength refractory fiber board made of ceramic fiber. It is an essential high temperature refractory material. Ceramic fiber board must be stored properly to fulfill its high temperature properties.
Ceramic fiber board is made of ceramic fiber cotton by vacuum forming. It has tough texture, high strength, superior high temperature performance, excellent support force, good tensile strength and impact resistance. Its strength is better than the fiber blanket and vacuum formed felt. It will be gathered together when contact with water and its hardness will be decreased. In this case, it is easy to fall off when touched. So, waterproofing is very important for the storage of ceramic fiber board.
Ceramic fiber board should be stored in dry circumstances with no water and moisture. The building should be watertight and kept dry. Ceramic fiber board should have waterproof plastic film inside and be covered with cartons and placed on the ground with pallets. It should be placed on pallets without contact with the ground, at least 20 mm away from the ground. In the rain season, ceramic fiber products should be covered with a waterproof canvas. Pay attention to water leakage if it is stored in iron house.

The difference between refractory bricks and insulation bricks

As their names imply, refractory brick is used to withstand high temperature and flame, while insulation brick is used to insulate and reduce heat loss. The insulation bricks seldom directly contact flame, while refractory bricks can directly contact flame. Both have their advantages and are used in different parts of furnaces.
Insulation bricks always have thermal conductivity between 0.2-0.4 w/m.k (350±25℃), while refractory bricks have thermal conductivity above 1.0w/m.k(350±25℃). So, insulation bricks have better insulation performance than refractory bricks. the refractoriness of insulation bricks is usually under 1400 degree, while that of refractory bricks is above 1400 degree. insulation bricks are generally lightweight materials with a density between 0.8-1.0g/cm3, while that of refractory bricks is above 2.0g/cm3.
Refractory bricks have better mechanical strength, long service life and better chemical stability. They do not react with batch materials. They have better high temperature performance and can withstand high temperature up to 1900℃.
Refractory bricks and insulation bricks are quite different. Their applications and functions are quite different. It is important to select the right materials according to the actual conditions.

How to Select Insulation Bricks

The use of insulation bricks in the thermal equipment can greatly reduce the heat loss and the weight of furnaces and improve the thermal efficiency and labor productivity.
For most thermal equipment, in order to save energy and improve the working conditions, insulation is necessary. However, for some equipment, insulation is not necessary, given the pros and cons of insulation. Therefore, the actual conditions and the properties of insulation bricks should be taken into consideration when selecting the right insulation bricks.
The insulation bricks can be divided into the following types:
1) Fire clay insulation brick GB/T 3994-2005
2) High alumina insulation brick
3) Mulite insulation brick
The principles for selecting insulation bricks include:
1) It should not affect the service life of the entire refractory masonry;
2) For continuously working high temperature furnaces, generally large area insulation is reasonable and can reduce the heat loss. However, for some special areas such as the open hearth roof, insulation may reduce the service life. For periodically working furnaces, regenerative heat loss is the main factor of heat loss. Insulation may increase the temperature of masonry and increase regenerative heat loss. So, whether periodically working furnaces should be insulated is determined after calculating the heat storage and heat loss.
3) Since the insulation bricks have high porosity, they cannot withstand too much load and should not directly contact the molten metals, molten slags and high-temperature dust.
4) Insulation bricks have low strength. The brick joints and expansion joints should be properly disposed avoid the damage caused by volume expansion. Insulating firebrick should not be subjected to intense mechanical vibration, shock and friction;
5) Since insulation bricks have big reheating linear shrinkage, the maximum working temperature should be 100℃ less than the firing temperature.