Cordierite Mullite Brick Introduction
Cordierite mullite bricks are sintered with mullite, andalusite, slab corundum and cordierite as the main raw materials, supplemented with ultrafine powder reinforced matrix, which is kneaded, formed, dried and fired at low and medium temperatures, due to cordierite. The firing temperature range is very narrow, and the firing temperature is extremely critical. The mullite cordierite brick prepared by the process not only has excellent thermal shock resistance (1100℃ water cooling ≥ 100 times without crack), but also has a high temperature performance (softness is more than 1500 °C), suitable for ceramic industrial kiln car surface, porous kiln push plate, roller kiln gasket, casing ceramic enamel and hot blast stove ceramic burner.
The cordierite mullite refractory brick is also known as the mullite cordierite brick. The cordierite mullite refractory brick have their own unique characteristics. In order to improve the use effect, the two kinds are combined and made through repeated development experiments.The refractory product solves the problem of low toughness and low softness of cordierite, and at the same time improves the thermal shock resistance of mullite brick.
Cordierite Mullite Brick Raw Material Introduction
Cordierite has a chemical composition of 2MgO·2A12O3·5SiO2, which is a kind of silicate mineral. Because cordierite has low thermal expansion coefficient, excellent thermal stability and good thermal shock resistance, it has been widely used as thermal shock resistance data for automotive exhaust gas purification equipment, catalyst carriers, heat-resistant coatings, heat exchanger data, electronic packaging materials, foam ceramics, printed circuit boards, etc., as well as some hot and cold mutations, such as ceramics Heat exchangers, hot blast stoves, crucibles, slabs, pillar bricks, etc.
Cordierite Manufacturing Process
Cordierite is a product which is excellent in heat shock resistance and often uses a special composition. From raw refractory material, a refractory product having a high content of cordierite (MgO 13.8%, Al2O3 34.8%, SiO2 51.4%) can be obtained. Cordierite refractory data has high mechanical strength and low thermal expansion coefficient, and the flexural strength can reach 95 MPa. The linear expansion coefficient is 2.0×10-6°C-1 in the range of 20-800℃. Mostly used in the ceramic industry, such as slabs, storage slabs, slabs, perforated plates, push plates and palms. Usually, talc refractory materials with high thermal shock resistance are produced by using talc α-Al2O3 and Suzhou soil; talc, clay and bauxite are used to produce cordierite refractory bricks with general thermal shock resistance. The billet composition with the best thermal shock resistance is in the region of the oblique hard pyroxene and cordierite of the Al2O3-MgO-SiO2 ternary system, and the sintering scale is narrow. The billet composed of kaolin and 10% to 30% talc has a sintering scale of 90-240℃,when the talc content is 40%-70%, the sintering scale is sharply reduced to 10-30℃.
A porous body excellent in thermal shock resistance can be obtained from a green body composed of 30% to 40% of talc, 30% to 40% of plastic clay, and about 20% of calcined A12O3. The refractory product is fired at a temperature of 1380 to 1410 ° C to obtain a refractory product having a cordierite content of 60%. In order to obtain as much cordierite as possible during the firing process and prevent the high temperature firing of the lower tombstone into mullite and glass phase, the refractory material can be compounded, mixed, compacted, and then calcined at 1350 ℃, pre-composed Cordierite, which is destroyed and molded, is fired at about 1400 °C. A cordierite refractory brick having a swelling coefficient of 1.4 × 10 -6 ° C -1 can be obtained. Cordierite products have good thermal shock resistance and residual expansion. For porous cordierite products, the linear expansion coefficient is (1~1.2)×10-6·°C-1 in the range of 20~100°C, in 20～200. The coefficient of linear expansion in the °C scale is (1 to 1.5) × 10-6 ° C -1 , and is 2.0 × 10 -6 ° C -1 in the range of 20 to 800 ° C.
Cordierite Mullite Brick Feature
Cordierite in mullite cordierite bricks has a small coefficient of thermal expansion (about 1×10-6 to 2×10-6°C-1 at 25~1 000 °C), which have good thermal shock resistance and chemical stability. However,cordierite mullite refractory brick refractoriness is low, and it will differentiate at 1470 °C. The refractory degree of refractory cordierite mullite brick is high and the coefficient of thermal expansion is large (4.5×10-6°C-1). It can be seen that the swelling coefficient of cordierite and mullite is quite different, and microcracks can be attacked in cordierite mullite refractory bricks, which is beneficial to the thermal shock resistance of the data.
Cordierite Mullite Brick Production Process
Because the formation temperature and differentiation temperature of cordierite are relatively close. That is to say, the burnt scale of cordierite is relatively narrow, and there is no significant cordierite formation at a lower temperature, and the progress of the firing temperature leads to the formation of many glass phases. Therefore, in the production of mullite cordierite kiln furniture, in order to reduce the glass phase, improve the thermal stability of the kiln furniture, facilitate the control of the firing process in the production, and choose to make cordierite and make mullite as the material. In the molding process, because of the injection molding, high pressure grouting and machine forming can be used.
(1) High fire resistance, excellent thermal shock resistance and chemical stability. The firing of modern ceramics is carried out in the direction of fast burning, and the thermal shock resistance is particularly important, the kiln furniture with high chemical stability at high temperature is not easy to react with the refractory product.
(2) Normal temperature and high temperature strength. One of the effects of the kiln furniture is load bearing. It is necessary to fully absorb the load of the products and the kiln furniture, the high strength kiln furniture materials can make the kiln furniture light and thin, to improve the density of the kiln and improve the quality of the refractory products.
(3) Excellent thermal conductivity and low heat storage. The production of refractory products tends to be high quality, high yield, low consumption, and the firing process tends to be fast, which requires less heat storage and faster heat transfer in the kiln.
(4) The appearance is regular and the scale is accurate. The deformation of the refractory product is related to the flatness of the crucible; the scale of the crucible is accurate, which is conducive to mechanized operation and improves the production efficiency.
