Aluminum oxide
Thermal Stability and Performance: Characterized by a melting point of 2040°C and boiling point of 2980°C, alumina demonstrates exceptional thermal endurance, rendering it suitable for high-temperature applications including crucible manufacturing and abrasive material production.
Mechanical Hardness and Crystallography: With a Mohs hardness rating of 8.8, alumina ranks among the hardest known engineering materials, enabling applications in precision cutting instruments and synthetic gemstone fabrication.
Industrial Application Diversity: Alumina serves critical functions in bearing systems, high-velocity mechanical components, and corundum-based crucibles engineered to withstand operational temperatures reaching 1800°C in chemical processing environments.
Chemical Stability and Safety Considerations: The material exhibits notable chemical inertness and water insolubility, though prolonged inhalation of particulate matter requires implementation of respiratory protection measures due to potential pulmonary system impairment risks.
Alumina, with the chemical formula Al₂O₃, is commonly known as aluminum oxide. This thermally stable white powder exhibits water insolubility and possesses defined physical characteristics: melting point 2015°C, boiling point 2980°C, specific gravity 4.0, and Mohs hardness 8.8. The compound crystallizes in multiple polymorphic forms, among which the α and γ phases represent the predominant crystalline configurations.
Melting point | 2040 °C(lit.) |
Boiling point | 2980°C |
density | 3.97 |
bulk density | 950-1100g/L |
vapor pressure | 17 mm Hg ( 20 °C) |
refractive index | 1.765 |
Fp | 2980°C |
storage temp. | Sealed in dry,Room Temperature |
solubility | Miscible with ethanol. |
form | powder |
color | White to pink |
Specific Gravity | 3.97 |
Odor | Odorless |
PH Range | 3.5 - 4.5 |
PH | 7.0±0.5 ( in H2O) |
Water Solubility | INSOLUBLE |
semiconductor properties | <0001> |
Crystal Structure | Trigonal |
crystal system | Three sides |
Merck | 14,356 |
Space group | R3c |
Lattice constant | a/nmb/nmc/nmα/oβ/oγ/oV/nm30.475890.475891.299190901200.2548 |
Exposure limits | ACGIH: TWA 1 mg/m3 |
Dielectric constant | 4.5（Ambient） |
InChIKey | PNEYBMLMFCGWSK-UHFFFAOYSA-N |
CAS DataBase Reference | 1344-28-1(CAS DataBase Reference) |
NIST Chemistry Reference | Aluminum oxide(1344-28-1) |
EPA Substance Registry System | Alumina (1344-28-1) |
Safety Information
Hazard Codes | Xi,F |
Risk Statements | 36/37/38-67-36/38-11-36 |
Safety Statements | 26-24/25-16-7-36 |
WGK Germany | - |
RTECS | BD1200000 |
F | 3 |
TSCA | Yes |
HazardClass | 8 |
HS Code | 28181010 |
Hazardous Substances Data | 1344-28-1(Hazardous Substances Data) |
Toxicity | Chronic inhalation of Al2O3 dusts may cause lung damage. |
Industrial production is achieved through thermal dehydration of aluminum hydroxide precursors. In geological formations, the α-polymorph occurs naturally as corundum, a mineral second only to diamond in hardness. The incorporation of chromophoric impurities generates colored variants of corundum, yielding precious gemstones including ruby (containing Cr³⁺ ions) and sapphire (incorporating Ti³⁺, Fe²⁺, and Fe³⁺ cations).
Contemporary technological processes facilitate the synthesis of artificial gemstones through precisely controlled crystallization of molten alumina. These laboratory-grown crystals achieve quality parameters equivalent to their natural counterparts while enabling extensive industrial utilization. They function as precision bearings in high-velocity mechanical systems, serve as jewel bearings in chronometric instruments, perform as advanced abrasive media, and operate as thermal-resistant components. Additionally, synthetic corundum crucibles demonstrate exceptional thermal endurance, maintaining structural integrity at operational temperatures reaching 1800°C.
