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What Is Silica Insulation Brick

Date:2016-05-18 10:13 | From:Zhengzhou Sunrise Refractory | Author:admin
Silica insulation brick is a type of light weight insualtion brick with a silica content of more than 91% and a density of less than 1.2 g/cm3. It is widely used for the insulation of the industrial furnaces. 
What Is Silica Insulation Brick
Silica insulation brick is made of silica by adding inflammable substances (coke, anthracite coal, sawdust, and carbonized rice husk) or foaming agents to form porous structure. Generally add 35-45% anthracite coal or about 30% coke as inflammable substances. Since there are Fe2O3 and Al2O3 in the ash of coke and anthracite coal, there is no need to add iron scales. Similar to the production of common silica brick, some mineralizing agents will be added to promote the transformation of quartz. Pulp waste is added as a binging agent to increase the strength of bricks. 
 
The raw materials and water are added into a kneading machine by a certain proportion and kneaded into mud. Then the mud is shaped into bricks by mechanical or manual molding. The bricks are dried until the residual water is less than 0.5% in order to avoid volume expasnion caused by the crystal transformation of SiO2. when firing, increase and decrease the temperature slowly. 
 
The mineral composition of the brick consists of 78%-86% tridymite, 13%-15% cristobalite and 4%-7% quartz. In general, its density is 0.9-1.1g/cm3, cold crushing strength is 2.0-5.9MPa and thermal conductivity is 0.35-0.42W/(m•K). 
 
Except the insulation properties, it largely retains the properties of silica bricks. Its softening temperature under load is more than 1620℃, close to that of dense silica brick. it has only a small amount of residual expansion and better thermal stability than dense silica brick. 
 
Silica inuslation brick can be long-term used under high temperature (1500-1550℃) conditions without contact with slags. Its service temperature should be no more than 1550℃ and not directly contact molten materials and corrosive gases. Since silica duct is harmful to the human body and its production is more complex than fire clay insulation brick and high alumina insulation brick, it takes account of a small properion of the total production of insulation materials. 
 
Silica inuslation brick is suitable for the insulation of hot stoves and glass furnaces. it can be divided into 2 grades. The grade Ⅰ can directly contact with the flame and is suitable for the insulation of the roof of reheating furnaces and portland industrial furnaces. The grade Ⅱ can be used for the insulation of common insutrial furnaces. 
 
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