The composition and application fields of tabular corundum. Tabular corundum is corundum that is not smelted in an electric furnace. It is made of smelted alumina (Al2O3 content of more than 85%), which is wet-milled into a 3-micron micro-particle slurry (a binder should be added during ball milling), and then pressed into various geometric shapes of abrasive particles, and sintered at 1500°C. The composition of tabular corundum. The main chemical components of sintered tabular corundum are: Al2O3 (85~88%), SiO2 (3~4%), TiO2 (3.5~4.5%), Fe2O3 (5.6~6.5%). It has an α-Al2O3 microcrystalline structure, high toughness, can withstand greater grinding pressure without breaking, and can cut thicker metal layers, with a lateral feed of up to 6mm or more.
Plate-shaped corundum is used as various reaction vessels and pipelines, and chemical pump components in chemical systems due to its high hardness, good wear resistance and high strength. It is used as mechanical parts and various molds, such as wire drawing molds and pencil core extrusion molds. It is used as cutting tools, abrasives, bulletproof materials, human joints, sealing grinding rings, etc.
Because plate-shaped corundum has high-temperature insulation, it is used as threaded tubes and protective tubes for thermocouples. The insulation used in atomic reactors is still excellent, and the loss and dielectric constant are not large. It is widely used in the electronics industry for solid integrated electric furnace substrates, tube sockets, shells, porcelain frames, thin windows, missile radar antenna protection covers, etc.
Transparent corundum products can be used to make lamps and microwave fairings. In addition, Na-b-Al2O3 products are electrolyte materials for making sodium-sulfur batteries.
Al2O3 is an ionic crystal with a very stable structure. When used at high frequency, high voltage and high temperature, its insulation is still excellent, and the loss and dielectric constant are not large. It is widely used in the electronics industry for solid extruded circuit substrate tube sockets, shells, porcelain frames, micro-glass windows, missile radar antenna protection covers, etc.
Corundum products have good airtightness and are airtight even at high temperatures. Therefore, they are widely used in electric vacuums. Plate corundum manufacturers have learned that corundum is used to make various large electronic tube shells and dual-in-line package shells in solid microcircuits.
The Role of Tabular Corundum in the Foundry Industry
Tabular corundum plays an important role in the foundry industry, which is mainly reflected in the following aspects:
1. As a high-performance refractory material
Excellent physical properties: Tabular corundum has a coarse crystal and well-developed α-Al₂O₃ crystal structure, which gives it high purity and good volume stability. It has small pores and more closed pores, and its porosity is comparable to that of fused corundum, which gives it excellent thermal shock resistance and spalling resistance.
Improving the performance of refractory materials: Tabular corundum can be used as the main component in aluminum-carbon, aluminum-magnesium-carbon, magnesium-aluminum-carbon, magnesium-spinel, and aluminum-chromium refractory bricks, significantly improving the performance of these refractory materials. It can also be introduced into high-aluminum amorphous refractory materials as an enriched alumina component further to enhance the material’s refractoriness and service life.
Improve mold life: Tabular corundum is often used to manufacture key components of casting molds, such as sprue sleeves and runner plates, due to its high hardness and wear resistance. These components need to withstand the scouring and erosion of high-temperature molten metal during the casting process. The use of tabular corundum can significantly improve the wear resistance and service life of the mold.
Optimize the casting process: Tabular corundum has high thermal conductivity and low thermal expansion coefficient, which helps to quickly dissipate heat and reduce thermal stress during the casting process. This helps to reduce casting defects such as pores, shrinkage holes and cracks, and improve the quality and yield rate of castings.
3. Application in casting auxiliary materials
Used as casting material and prefabricated parts: Tabular corundum can be used as aggregate for casting material and prefabricated parts, and used to manufacture various casting refractory materials. These materials can provide good thermal insulation and support during the casting process, ensuring the smooth progress of the casting process.
Used as sliding nozzles and breathable bricks: Tabular corundum is often used to manufacture casting auxiliary materials such as sliding nozzles and breathable bricks due to its excellent thermal shock resistance and erosion resistance. These auxiliary materials can ensure the smooth flow and discharge of molten metal during the casting process, while preventing defects such as pores and inclusions in the castings.
4. Other applications
Smelting of rare and precious metals and special alloys: Tabular corundum is often used in crucibles and vessels for smelting rare and precious metals and special alloys due to its high purity and good high-temperature resistance. This helps to ensure the smooth progress of the smelting process and the stability of product quality.
The Role of Tabular Corundum in Ceramics
The role of plate-shaped corundum in ceramics is mainly reflected in the following aspects:
Improve the hardness and wear resistance of the glaze: Plate-shaped corundum has very high hardness and wear resistance, which enables it to significantly improve the hardness and wear resistance of the glaze when used as a ceramic glaze. The improvement of glaze hardness means that ceramic products can better resist physical damage such as scratches and wear during use, thereby extending the service life.
Improve the glossiness of the glaze: The crystal structure of plate-shaped corundum enables the glaze to form a smoother and flatter surface during the firing process, thereby improving the glossiness of the glaze and making the ceramic products look brighter and more beautiful.
Enhance the adhesion and overall aesthetics of the glaze: Plate-shaped corundum can help other materials in the glaze to better adhere to the surface of ceramic products, further enhancing the overall aesthetics of the glaze.
Improve chemical corrosion resistance:Tabular corundum has excellent chemical stability and can resist corrosion from a variety of chemical substances. Adding tabular corundum to ceramic glazes can effectively improve the chemical corrosion resistance of glazes, so that ceramic products can maintain stable performance in harsh environments such as acidic and alkaline.
Improve thermal stability: Tabular corundum has high refractoriness and high thermal shock stability. Adding tabular corundum to ceramic glazes can improve the thermal stability of glazes, making it less likely for the glaze surface to crack or peel off during firing, thereby improving the overall quality of ceramic products.
Improve glaze fluidity: The particle shape and distribution characteristics of tabular corundum help improve the fluidity of glazes, so that the glaze can be more evenly covered on the surface of ceramic products during coating, reducing the generation of bubbles and defects, and further improving the beauty and quality of ceramic products.
Improve mechanical strength: The addition of tabular corundum can also improve the mechanical strength of ceramic products, such as compressive strength and flexural strength, so that ceramic products can better withstand the impact and extrusion of external forces during use, and improve safety in use.
