Corundum
[CAS# 1302-74-5]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Oxides and peroxides >> Metal oxide
• Name: Corundum
• Synonyms: APA 0.5; Abramant F 36; Abramax F 46; Abramax F 54; Alodur ZWSK 1T180; Alodur ZWSK 1T200; BA 95 325F; Ceralox APA 0.5; Cristalba CAHPF 240; Dermagrain 900; Dural F 30; Dural HT; Dural HT-F 24; Dural P 120; EB 99; EKF 100; EKF 500; Electrocorundum; F 220; F 240; F 280; F 280 (mineral); F 800; F 800 (mineral); FN 237
• Molecular Formula: Al₂O₃
• Molecular Weight: 101.96
• CAS Registry Number: 1302-74-5
• EC Number: 603-397-4
• SMILES: O=[Al]O[Al]=O

Properties

• Density: 14.05 g/cm^3*
• Melting point: 2054 °C^**
• Refractive index: 1.771^***

^* Gottfried, C.

^** Fomichev, E. N.

^*** Kiselev, V. I.

Discovery and Applications

Corundum, a crystalline form of aluminum oxide (Al₂O₃), is one of the most important and widely used minerals in various industries due to its exceptional hardness and chemical stability. The substance has a rich history and a range of applications that highlight its significance in material science and industry.

The discovery of corundum dates back to ancient times, with references to its use as an abrasive and gemstone found in historical texts. The mineral is found in various geological settings, including metamorphic rocks, igneous rocks, and alluvial deposits. It occurs naturally in a range of colors, including colorless, blue (sapphire), and red (ruby), depending on the presence of trace elements. Corundum is formed under high-pressure and high-temperature conditions, contributing to its hardness and durability.

The most significant property of corundum is its hardness, which is second only to diamond on the Mohs scale. This characteristic makes it an invaluable material in the production of abrasives. Synthetic corundum, produced through methods such as the Bayer process, has been widely used as an abrasive in grinding, cutting, and polishing applications. Its ability to effectively wear down other materials makes it ideal for use in sandpapers, grinding wheels, and other abrasive tools.

In addition to its use as an abrasive, corundum's hardness and chemical inertness make it a critical material in the manufacture of cutting tools and industrial machinery. For example, corundum is employed in the production of high-performance cutting tools and wear-resistant components that require exceptional durability and resistance to wear and corrosion. Its use extends to various industrial applications, including the aerospace, automotive, and metalworking industries.

Corundum's significance is also highlighted in its role as a gemstone. The red variety, known as ruby, and the blue variety, known as sapphire, are highly valued for their beauty and are used in fine jewelry. The color variations in these gemstones are due to the presence of different trace elements, such as chromium for ruby and iron and titanium for sapphire. The beauty and rarity of these gemstones have made them highly sought after in the luxury market.

Synthetic corundum, produced through methods such as the Verneuil process or the flame fusion technique, has revolutionized the gemstone industry. Synthetic sapphires and rubies are used not only in jewelry but also in various industrial applications, including high-durability windows, optical lenses, and electronic substrates. The ability to control the growth conditions and purity of synthetic corundum has allowed for the creation of materials with tailored properties and applications.

In addition to its applications in abrasives and gemstones, corundum is used as a refractory material due to its high melting point and chemical resistance. Refractory bricks made from corundum are used in high-temperature furnaces, kilns, and reactors, where their durability and stability under extreme conditions are crucial.

Handling corundum requires standard safety precautions, especially when dealing with its abrasive forms. Dust from corundum abrasives can be a respiratory hazard, and appropriate protective measures should be taken to minimize exposure.

Ongoing research continues to explore new applications and improvements in the use of corundum. Advances in material science and engineering are leading to the development of new synthetic corundum materials with enhanced properties for a variety of applications.

In summary, corundum is a versatile and important material with a wide range of applications due to its hardness, chemical stability, and role as a gemstone. Its discovery and development have had a significant impact on various industries, and continued research promises to expand its applications further.

References

1987. [A preliminary report on Al2O3-ceramic delayed implantation]. Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology, 22(2).
URL: https://pubmed.ncbi.nlm.nih.gov/3476276

2023. Synthesis of Polyamide-Al2O3 Nanocomposite Membranes Using the Nanofiltration Phase Separation Method. The 6th Mechanical Engineering, Science and Technology (MEST 2022) International Conference.
DOI: 10.2991/978-94-6463-134-0_58

1990. Clinical experience with alumina ceramic transcutaneous connector to prevent skin-exit infection around CAPD catheter. Advances in peritoneal dialysis. Conference on Peritoneal Dialysis, 6.
URL: https://pubmed.ncbi.nlm.nih.gov/1982797