Classification and Uses of Refractory Plastics
Fire-resistant plastic has strong plasticity. The tamping method is usually used for construction, and the ceramic structure is formed after strong tamping and high-temperature baking. The medium- and high-temperature structure has high strength, strong wear resistance, and excellent thermal shock resistance. Refractory plastics vary according to the materials used, and aluminum silicate refractory plastics are commonly used. Such as clay refractory plastics, high alumina refractory plastics, and corundum refractory plastics. Different binder methods have different performances and uses.
The composition of refractory plastics is the same as that of refractory castables. They are all made of refractory aggregates and powders of different particles, with the addition of binders, plasticizers, preservatives, anti-shrinkage agents, and other materials. The different bonding methods are mainly divided into three categories: clay-bonded plastics, phosphate-bonded plastics, and aluminum phosphate-bonded plastics.
(1) Clay-bonded plastic is a mixture made of clay clinker and high-aluminum clinker as the main materials, and plastic clay as the binding agent. The mud is mixed with water and then pressurized to form bricks with a certain plasticity. The main characteristics of this material are its good thermal shock resistance and thermal spalling resistance. Mainly used for the roof and walls of steel rolling heating furnaces.
(2) Phosphoric acid combined plastic is made of clay clinker or high alumina bauxite clinker and corundum as the main materials. Phosphoric acid or acidic aluminum phosphate is used as a binding agent, and a mixture is prepared by adding plastic refractory clay, preservatives, and admixture materials. The characteristics of this material include high medium and high-temperature bond strength, strong wear resistance, and thermal shock resistance.
When producing phosphate-bonded plastic blanks, a two-step mixing process should be adopted. In the first step, 60% of the total required amount of phosphoric acid solution is mixed with refractory aggregate, powder, and plastic clay, and then mixed evenly and trapped for 24 hours. So that the refractory aggregate can fully absorb the phosphoric acid solution, and the metallic iron contained in the refractory aggregate (brought in during crushing) can fully react with the phosphate to release H2 gas. Then perform the second step of kneading. During kneading, add preservatives and the remaining approximately 40% phosphoric acid solution. When the required plasticity index is reached after mixing evenly, it is then pressed or extruded into a green body, and the green body is sealed and stored with a plastic film.
The phosphoric acid-bonded plastic prepared from a phosphoric acid solution with a density of 1.25g/cm3, clay clinker, and high-aluminum clinker uses aluminum phosphate solution as the binding agent. High-temperature wear-resistant plastics can be prepared by using corundum as aggregate and a-Al2O3 fine powder and micro powder as powder.
Aluminum phosphate or phosphoric acid combined plastics are widely used in industrial kilns in the metallurgical, petrochemical, power, and mechanical industries. Mainly used for thermal shock resistance, erosion resistance, and wear resistance lining. Such as the burner of the heating furnace, the discharge port of the cement rotary kiln, the feeding port of the vertical kiln, the lining of the high-temperature cyclone separator, etc.
(3) Aluminum sulfate bonded plastics use clay clinker or high alumina bauxite clinker and corundum as the main materials and aluminum phosphate solution as the binding agent. A mixture is prepared by adding plastic refractory clay, preservatives, and admixture materials. The characteristics of this material include high medium and high-temperature bond strength, strong wear resistance, and thermal shock resistance. Low production cost and wide range of uses.
Aluminum sulfate is a solid substance. It must be dissolved in water before use. Its density reaches 1.15-1.2g/cm3. Aluminum sulfate combined with plastic construction method. The first mixing - trapped material - the second mixing - use. The first mixing is to add 60%-70% of the required aluminum sulfate solution. The purpose is to wet the aggregate and the solution so that the iron in the refractory aggregate reacts with aluminum sulfate to generate H2 and discharge it to prevent expansion after being made into a green body. During the second mixing, add the remaining 30%-40% aluminum sulfate solution, and then squeeze the mud into a blank. Seal the package with polyethylene film to prevent moisture from evaporating and losing plasticity.
Aluminum sulfate-bonded plastics are mainly used for industrial furnace linings with high structural strength. For example, it can be used as prefabricated blocks for the bottom of annular heating furnaces, forging furnace linings, shaft kiln linings, etc. Rongsheng Refractory Materials Manufacturer is a powerful manufacturer and seller of refractory materials. Our environmentally friendly, fully automatic unshaped refractory material production line is dedicated to providing long-life refractory lining materials for high-temperature industrial furnace linings. Contact us to get free samples and quotes.
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