Alumina (Al2O3), or aluminum oxide, is one of the most widely used advanced ceramics due to its outstanding combination of mechanical, thermal, and dielectric properties. It occurs naturally as corundum and can be synthesized in various crystalline forms, with ?-alumina being the most thermodynamically stable. Owing to its high hardness, compressive strength, and resistance to wear, alumina is extensively used across high-temperature, structural, and electronic applications.
Material Overview
High-purity alumina has a typical density of 3.95–3.99 g/cm³, a hardness of 20 GPa, and a flexural strength of 300–400 MPa. It retains structural integrity at temperatures exceeding 1700 °C and exhibits excellent resistance to corrosion and oxidation. Electrically, alumina has a dielectric strength of 12–15 kV/mm and a resistivity above 10¹? ?·cm, making it one of the most reliable ceramic insulators. The combination of low thermal expansion (~8 × 10?? K?¹) and high thermal conductivity (25–35 W/m·K) provides remarkable thermal shock resistance.
Recent research has advanced the design of alumina-based composites to enhance mechanical performance. Yang et al. (2024) demonstrated that continuous alumina fiber–reinforced Al2O3/Al2O3 composites exhibit exceptional thermal stability, retaining 95% of their strength after 100 hours at 1200 °C. Sun et al. (2025) reviewed developments in alumina design, emphasizing structural optimization for improved fracture toughness and durability under aerospace and industrial furnace conditions. Thermally sprayed Al2O3 coatings have also gained attention as high-performance insulators for electrical and electronic systems operating under extreme heat, according to Junge et al. (2022). Porosity and grain morphology remain key determinants of mechanical strength, as shown by Mamun et al. (2021), who reported that sintered alumina samples exhibited a direct inverse correlation between porosity and compressive strength.
Furthermore, Arcaro et al. (2017) found that the incorporation of nano-Al2O3 into lithium–zirconium–silicate (LZS) glass ceramics significantly reduced the coefficient of thermal expansion and improved dimensional stability, confirming alumina’s value in glass-ceramic composites and precision components.
Applications and Advantages
Alumina’s versatility makes it a material of choice for crucibles, furnace tubes, thermocouple sheaths, electronic substrates, and cutting tools. High-purity grades are essential for wear-resistant and electrical insulation components, while fiber and powder forms are employed in composites and coatings for aerospace and energy systems. Alumina’s bio-inertness also supports its use in dental and biomedical implants.
Goodfellow Availability
Goodfellow offers Alumina (Al2O3) in multiple forms, including bolts, fibers, powders, and spheres, suitable for thermal, mechanical, and dielectric applications. Custom compositions and grain sizes can be specified for research and industrial use. Explore alumina and related ceramic materials through the Goodfellow product finder.
References
- Sun, Y., Li, S., Zhao, Q., Cong, Z., Xia, Y., Jiao, X.H., & Chen, D. (2025). Recent advancements in alumina-based high-temperature insulating materials: Properties, applications, and future perspectives. High-Temperature Materials. https://doi.org/10.70322/htm.2025.10001
- Yang, F. H., Jiang, Y., Liu, H., Zhang, Y., & Sun, X. (2024). Microstructure, mechanical properties, and thermal stability of Al2O3/Al2O3 ceramic matrix composites obtained from submicron-sized powders. Ceramics International. https://doi.org/10.1016/j.ceramint.2023.12.289
- Junge, P., Rupprecht, C., Greinacher, M., Kober, D., & Stargardt, P. (2022). Thermally sprayed Al2O3 ceramic coatings for electrical insulation applications. International Thermal Spray Conference. https://doi.org/10.31399/asm.cp.itsc2022p0072
- Al Mamun, M. A., Mohtasim, S. M., & Islam, M. N. (2021). Property analysis of sintered porous aluminum oxide. AIP Conference Proceedings. https://doi.org/10.1063/5.0037605
- Arcaro, S., Moreno, B., Chinarro, E., Salvador, M. D., & Borrell, A. (2017). Properties of LZS/nano-Al2O3 glass-ceramic composites. Journal of Alloys and Compounds, 722, 569–576. https://doi.org/10.1016/j.jallcom.2017.03.299