Фасонные огнеупорные кирпичи, называемые огнеупорными, способны выдерживать различные физико-химические изменения и механические воздействия при высоких температурах. А специальные фасонные огнеупорные кирпичи — это огнеупорные материалы определенной формы и размеров.
According to the preparation method, the shaped refractory bricks can be divided into fired bricks, unfired bricks, electrofusion bricks (fusion casting bricks), refractory thermal insulation bricks. In addition, special shape refractory bricks can be divided into standard bricks, ordinary bricks, turn type and so on according to shape and size. Shaped refractory bricks can be used as high-temperature building materials and construction materials for building furnaces and various thermal equipment.
The main feature of profiled refractory brick is high early strength, 3-7 days maximum compressive strength at room temperature up to 30MPa or more. The disadvantage is poor volume stability at medium temperature, the strength decreases, the maximum drop can reach 40% or so, so the room temperature compressive strength requirements should meet the requirements of the project and national standards. Decrease in strength at temperature is the main factor: low calcium high alumina cement profiled refractory bricks in the heating furnace furnace process of heating furnace to reach a certain temperature (350 ℃ or so), hydride began dehydration, transformation of cementite hydride structure, compactness and strength of the cast material volume reduction, cast material at this time, the body strength has fallen to the lowest point, after generally stabilized.
As the heating temperature rises to 1100 ℃, the cementite gradually sintered, the refractory brick crystal type mold begins to turn into mullite crystals. As the temperature continues to rise, mullite crystals continue to grow, the glass phase matrix in the casting material is in the liquid state, the formation of high-temperature ceramic sintered mold, the strength is greatly increased. At a temperature of about 1300 ℃, the strength of shaped refractory brick can reach more than 60 MPa. This is an essential feature of shaped refractory bricks in the high-temperature state.