Aluminium oxynitride
| Aluminium oxynitride | |
|---|---|
|
Aluminium oxynitride |
|
| Identifiers | |
| Abbreviations | ALON |
| CAS number | 12633-97-5  |
| Properties | |
| Molecular formula | (AlN)x·(Al2O3)1-x, 0.30 ≤ x ≤ 0.37 |
| Appearance | White or transparent solid |
| Density | 3.696–3.691 g/cm3[1] |
| Melting point | |
| Solubility in water | insoluble |
| Refractive index (nD) | 1.79[2] |
| Structure | |
| Crystal structure | cubic spinel |
| Lattice constant | a = 794.6 pm[2] |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
Aluminium oxynitride or AlON is a transparent polycrystalline ceramic with cubic spinel crystal structure composed of aluminium, oxygen and nitrogen. It is currently marketed under the name ALON by Surmet Corporation.[3] ALON is optically transparent (≥80%) in the near ultra violet, visible and near infrared regions of the electromagnetic spectrum. It is 4 times harder than fused silica glass, 85% as hard as sapphire and nearly 15% harder than magnesium aluminate spinel. The material is stable up to 1,200 °C (2,190 °F).[1] It can be fabricated to transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. Because of its relatively light weight, optical and mechanical properties, and its resistance to damage due to oxidation or radiation, it shows promise for use as infrared, high temperature and ballistic and blast resistant windows. Manufacturing methods continue to be refined. At US$10–$15 per square inch the cost is currently (2005) higher than that of other ballistic resistant window materials.
Contents |
[edit] Properties
- Mechanical[2]
- Young modulus 334 GPa
- Shear modulus 135 GPa
- Poisson ratio 0.24
- Knoop hardness 1800 kg/mm2 (0.2 kg load)
- Fracture toughness 2.0 MPa·m1/2
- Flexural strength 0.38–0.7 GPa
- Compressive strength 2.68 GPa
- Thermal and optical[4]
- Specific heat 0.781 J/(g·°C)
- Thermal conductivity 12.3 W/(m·°C)
- Thermal expansion coefficient ~4.7×10−6/°C
- Transparency range 200–5000 nm
In a 1989 review, Corbin summarized research showing that ALON appears to be radiation resistant and resistant to damage from various acids, bases and water.[5]
[edit] Applications
ALON is used in various defense and Infrared (IR) related applications such as Recce sensor windows, specialty IR domes with different shapes such as hemispherical, hyper-hemispherical and tangent ogive domes, transparent armor, windows for laser communications, and in some semi-conductor related applications[6] When formed and polished as a window, the material currently (2005) costs about US$10 to US$15 per square inch (~ US$20,000/m2).[2]
[edit] Manufacture
ALON is a polycrystalline ceramic material which can be fabricated to windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. It is made primarily of aluminium, oxygen, and nitrogen, and can vary slightly in its components (such as varying the aluminium content from about 30% to 36%, which has been reported to affect the bulk and shear moduli by only 1–2%.[7]) The fabricated greenware is subjected to heat treatment (densification) at elevated temperatures followed by grinding and polishing to transparency. It remains transparent until about 2100 °C. The grinding and polishing substantially improves the impact resistance and other mechanical properties of armor.[4] Densities of 85% of the theoretical can be achieved. It is 85% as hard as sapphire and 15% harder than magnesium aluminate spinel. ALON is four times harder than fused silica glass, thus making it useful in a wide range of armor applications.
[edit] See also
[edit] References
- ^ a b c Sales (2003) (.PDF). ALON Optical Ceramic. Technical data. Surmet Corporation. http://www.surmet.com/docs/Product_sheet_ALON.pdf. Retrieved 2009-01-09.
- ^ a b c d Lee M. Goldman et al. ALON® Optical Ceramic Transparencies for Sensor and Armor Applications, Surmet
- ^ Richard L. Gentilman et al. Transparent aluminum oxynitride and method of manufacture U.S. Patent 4,520,116 Issue date: May 28, 1985
- ^ a b Joseph M. Wahl et al. Recent Advances in ALONTM Optical Ceramic, Surmet
- ^ Corbin, N (1989). "Aluminum oxynitride spinel: A review". Journal of the European Ceramic Society 5 (3): 143–154. DOI:10.1016/0955-2219(89)90030-7.
- ^ Zhu, Ming; Tung, Chih-Hang; Yeo, Yee-Chia (2006). "Aluminum oxynitride interfacial passivation layer for high-permittivity gate dielectric stack on gallium arsenide". Applied Physics Letters 89 (20): 202903. DOI:10.1063/1.2388246.
- ^ Graham, Earl K.; Munly, W.C.; McCauley, James W.; Corbin, Norman D. (1988). "Elastic properties of polycrystalline aluminum oxynitride spinel and their dependence on pressure, temperature and composition". Journal of the American Ceramic Society 71 (10): 807–812. DOI:10.1111/j.1151-2916.1988.tb07527.x.
[edit] Patents
- Process for producing polycrystalline cubic aluminum oxynitride JW McCauley U.S. Patent 4,241,000, 1980
- Aluminum oxynitride having improved optical characteristics and method of manufacture TM Hartnett, RL Gentilman U.S. Patent 4,481,300, 1984
- Transparent aluminum oxynitride and method of manufacture RL Gentilman, EA Maguire U.S. Patent 4,520,116, 1985
- Transparent aluminum oxynitride and method of manufacture RL Gentilman, EA Maguire U.S. Patent 4,720,362, 1988
- Transparent aluminum oxynitride-based ceramic article JP Mathers U.S. Patent 5,231,062, 1993
[edit] External links
- The Influence of Sintering Additives on the Microstructure and Properties of ALON. Yechezkel Ashuach. Master's Thesis, Technion – Israel Institute of Technology, 2003
- Solubility Limits of La and Y in Aluminum Oxynitride (AlON) at 1870°C Lior Miller and Wayne D. Kaplan. Department of Materials Engineering, Technion, Haifa, Israel, 2006
[edit] Links
|
|||||
