Corundum mullite bricks are refractory insulation materials that primarily consist of α-Al2O3 corundum as the main crystal phase. Due to their high heat resistance, strength, compressive strength, oxidation resistance, corrosion resistance, insulation properties, and good sealing, they have found increasing applications with the advancement of contemporary technology.
Approximately 5% of alumina trihydrate (Al(OH)3) is used in the production of refractory insulation materials, while another 5% is utilized in wear-resistant materials, electronic devices, petroleum and chemical plants, ceramics, paper industry, and other fields. The remaining 90% is primarily used in the power system for metallurgical processes. Many alumina trihydrate factories focus on the production of alumina trihydrate, such as alumina micro powder, low-sodium alumina trihydrate, γ-Al2O3, ultrafine α-Al2O3 silica powder, and high-purity Al(OH)3. However, there are currently no specialized alumina trihydrate processing plants for the production of refractory insulation materials.
Corundum mullite bricks utilize a diverse range of raw materials, ensuring easy availability. In terms of production and processing technology, they can be manufactured using traditional processes for corundum mullite brick production or adopting methods derived from traditional ceramics. Over the past half-century of research, development, and production, the processing technology has become increasingly refined, and the variety of materials continues to expand, making corundum mullite bricks widely applicable in the field of refractory insulation materials.
The main applications of corundum mullite bricks are as follows:
(1)High-temperature applications: Due to their heat resistance, corrosion resistance, and high toughness, corundum mullite bricks are used in various industries such as steel pouring nozzles, smelting precious metals, aluminum alloys, high-purity metal materials, glass-metal sealing in laser systems, and containers. They are also used as refractory insulation materials in high-temperature industrial kilns, such as furnace linings (walls and pipes) in iron smelting blast furnaces. They find applications in physical and chemical containers, automotive spark plugs, high-temperature resistant materials, and more. Low-silicon calcined corundum bricks with SiO2 content below 0.5% are used as furnace materials in carbon black, boron chemical plants, organic fertilizers, synthetic ammonia reactors, and biomass gasification furnaces.
(2)Wear-resistant applications: With their high strength, excellent wear resistance, and high compressive strength, corundum mullite bricks are used as components in chemical plant systems for corrosion-resistant vessels, pipelines, and pumps. They are also used in the manufacturing of mechanical parts, various molds such as wire drawing dies and pencil core mold nozzles, CNC blades, mold wear-resistant materials, EXO materials, human joints, and sealing grinding rings.
(3)High-temperature insulation applications: Corundum mullite bricks with their high-temperature insulation properties are used as sheathed tubes and maintenance tubes for thermocouples, insulation layers in atomic reactors, and other high-temperature insulation components. For example, even at a temperature of 1720℃, platinum-rhodium thermocouples have poor gas permeability.
(4)In the electronics industry, crystalline Al2O3 exhibits good insulation properties even at high frequencies, high voltages, and elevated temperatures. It is widely used in solid-state integrated circuit chip base steel plate sockets, casings, ceramic frames, microwave heating resonators, protective covers for cruise missile radar detection antennas, and more.
(5)Corundum products have excellent sealing properties and poor gas permeability even at high temperatures, making them widely used in electric vacuum pumps. For example, steel corundum is used to make various large and medium-sized rectifier tube shells and axial bearing direct-insert packaging casings in solid-state microcircuits.
(6)Corundum insulation materials, such as corundum mullite bricks, corundum hollow balls, and non-woven fabrics, are widely used as furnace bodies and rotary kilns in various high-temperature furnaces. They provide both heat resistance and thermal insulation.
(7)Transparent corundum products can be used to manufacture LED light tubes and microwave heating rectification covers. In addition, Na-β-Al2O3 products are used as raw materials for sodium-sulfur batteries. Corundum mullite bricks, especially fire-resistant products, are not only used in the production of refractory insulation materials but also in the production of decorative building materials, electronic devices, chemical plants, and mechanical equipment. Corundum refractory insulation materials belong to high-quality goods.