Introduction, application and production process of white corundum
White Fused Alumina (WFA) is an artificial abrasive made of industrial alumina powder as the main raw material, which is cooled and crystallized after high-temperature arc melting. Its main component is aluminum oxide (Al₂O₃), with a purity of more than 99%. It is white, hard, dense, and has excellent high temperature resistance, corrosion resistance and insulation properties. It is one of the most widely used advanced abrasives.
1. Product Introduction
White corundum is a kind of artificial corundum. Compared with brown corundum, it has lower impurity content, higher hardness, whiter color, no free silica, and is harmless to the human body. It is especially suitable for process occasions with high requirements for abrasive purity, color and grinding performance. White corundum has a Mohs hardness of up to 9.0, second only to diamond and silicon carbide. It has good self-sharpening properties, is not easy to adhere to the workpiece surface during grinding, and has fast heat dissipation. It is suitable for both dry and wet processing methods.
2. Main Applications
Due to its unique physical and chemical properties, white corundum is widely used in many high-end fields, including but not limited to the following aspects:
Abrasives and grinding tools
It is used to manufacture ceramic grinding wheels, resin grinding wheels, emery cloth, sandpaper, scouring pads, grinding pastes, etc. It is an ideal grinding material for high-carbon steel, alloy steel, stainless steel, glass, ceramics and other materials.
Sandblasting and polishing
It is suitable for metal surface cleaning, rust removal, surface strengthening and matte treatment. Because of its high hardness and non-toxic and harmless, it is often used for sandblasting and polishing of precision molds and stainless steel products.
Refractory materials
It can be used as aggregate or fine powder of advanced refractory bricks, castables, and casting materials. It is widely used in high-temperature environments such as steel, non-ferrous metal smelting kiln linings, glass kilns, etc.
Electronic/optical industry
It is used to manufacture high-purity ceramics, optical glass grinding, LED sapphire substrate polishing, semiconductor silicon wafer cleaning and grinding, etc., and high-purity ultrafine white corundum powder is required.
Functional filler
Used in rubber, plastic, coating, ceramic glaze and other industries to improve the wear resistance, thermal stability and insulation performance of materials.
3. Production process
The production process of white corundum is rigorous and scientific, mainly including the following key steps:
Raw material preparation
Select high-purity industrial alumina powder (Al₂O₃≥99%), screen and chemically test the raw materials to ensure that the impurity content is extremely low and the particle size is uniform.
Arc melting
Put the alumina powder into a three-phase arc furnace and melt it at a high temperature of about 2000℃. During the smelting process, the electrodes are heated to completely melt the alumina and remove impurities to form a pure corundum melt.
Cooling crystallization
After the melt is cooled, it naturally crystallizes to form blocky white corundum crystals. Slow cooling helps the development of grains and stable performance, which is a key link to ensure the quality of white corundum.
Crushing and magnetic separation
The cooled corundum crystals are crushed and finely crushed by mechanical equipment, and then impurities such as iron are removed by strong magnetic separation to ensure the purity of the finished product.
Crushing and screening
Use ball mills, air flow mills and other equipment to crush white corundum to the required particle size, and then use high-precision screening equipment to grade the particle size according to international standards (such as FEPA, JIS) to obtain sand or micro powder of different specifications.
Fine grading and cleaning (depending on the purpose)
For some high-end applications, such as electronic grade and optical grade white corundum powder, air flow classification, pickling and ultrasonic cleaning are carried out to further improve the purity and particle size control accuracy.
Quality inspection and packaging
The finished product needs to undergo a series of quality control processes such as chemical analysis (Al₂O₃, Fe₂O₃, Na₂O, etc.), particle size detection, whiteness detection, etc., and after passing the test, it is packaged according to customer requirements, generally in 25kg bags or ton bags.
As an industrial material with excellent performance, white corundum plays an irreplaceable role in many industries. It is not only an important representative of high-end abrasives, but also a key basic material in high-tech fields such as precision machining, functional ceramics, and electronic materials. With the continuous development of industrial technology, the market’s quality requirements for white corundum are also continuously improving, which also prompts manufacturers to continuously optimize processes, improve product performance, and develop in the direction of higher purity, finer particle size, and more stable quality.
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