The difference between silicon brick and semi-silicon brick

April 1, 2022

The difference between silicon brick and semi-silicon brick

Silica brick is refractory product with SiO2 content above 92%. The higher the content of SiO2 in silica raw materials, the higher the refractoriness of products, the ability of acid erosion resistance is very strong.

Semi-silica brick is made of pyrophyllite as the main raw material, and its refractoriness is more than 1700℃. Good thermal shock resistance, can withstand the impact of steel slag and metal, and has a strong creep resistance.

Silica brick belongs to a variety of acid refractory materials, has a strong resistance to acid slag or acid melt erosion ability, alkali erosion resistance is very poor, and the expansion coefficient of silica brick is very large. The volume of silica brick is stable between 300℃ and melting point. When heated to 1450℃, volume expansion of 1.5% ~ 2.2% will occur. The biggest disadvantage of silicon brick is poor thermal shock resistance and low refractoriness (generally 1690 ~ 1730℃), so its application scope is limited.

A semi-silica brick made of waxy stone. There will be micro expansibility. Because of the mineral composition of wax stone, the lattice size of pyrophyllite in its crystal structure changes little when heated, so it shrinks when roasted, and sometimes expands slightly. In the process of high-temperature use of semi-silica brick, pyrophyllite reacts with acidic slag, forming a layer of glaze substance with high viscosity on the surface of semi-silica brick, preventing the infiltration of acidic slag into the brick, and the ability to resist the erosion of acidic slag is also quite good.

The amount of silicon brick is large and the variety is large. It is mainly used in the carbonization chamber, combustion chamber and partition wall of coke oven and the kiln roof and kiln pool of glass kiln. There are also high temperature bearing parts of hot blast furnace, carbon baking furnace and other furnaces also use silica brick as lining. There are many kinds of silica brick, including silica brick for coke oven, silica brick for hot blast stove, silica brick for electric furnace, silica brick for glass kiln, etc.

The use range and amount of semi-silica brick is not as large as silica brick, which is extremely limited. Although it can be used as the bottom lining of ladle, hot metal ladle lining and flue, the semi-silicon brick is seldom used because of the improvement of steel quality.