Aluminium oxynitride

Aluminium oxynitride (marketed under the name ALON by Surmet Corporation[3]) is a transparent ceramic composed of aluminium, oxygen and nitrogen. Aluminium oxynitride is optically transparent (≥ 80%) in the near-ultraviolet, visible, and midwave-infrared regions of the electromagnetic spectrum. It is four times as hard as fused silica glass, 85% as hard as sapphire, and nearly 115% as hard as magnesium aluminate spinel. Since it has a cubic spinel structure, it can be fabricated to transparent windows, plates, domes, rods, tubes, and other forms using conventional ceramic powder processing techniques.

"ALON" redirects here. For the aircraft corporation, see Alon (disambiguation).
Aluminium oxynitride

Spinel structure of ALON
Names
Systematic IUPAC name
Aluminium oxynitride
Identifiers
Abbreviations ALON
Properties
(AlN)x·(Al2O3)1−x,
0.30 ≤ x ≤ 0.37
Appearance White or transparent solid
Density 3.691–3.696 g/cm3[1]
Melting point ~2150 °C[1]
insoluble
1.79[2]
Structure
cubic spinel
a = 794.6 pm[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Aluminium oxynitride is the hardest polycrystalline transparent ceramic available commercially.[2] Because of its relatively low weight, distinctive optical and mechanical properties, and resistance to oxidation or radiation, it shows promise for applications such as bulletproof, blast-resistant, and optoelectronic windows.[4] Aluminium oxynitride-based armor has been shown to stop multiple armor-piercing projectiles of up to .50 BMG.[5]

Aluminium oxynitride is commercially available in sizes as large as 18-by-35-inch (460 mm × 890 mm; 46 cm × 89 cm) monolithic windows.[6]

Properties

Aluminium oxynitride is resistant to damage from various acids, bases, and water.[7]

Mechanical

Aluminum oxynitride has the following mechanical properties:[2]

Thermal and optical

Aluminum oxynitride has the following thermal and optical properties:[8]

Applications

Aluminium oxynitride is used for infrared-optical windows, with greater than 80% transparency at wavelengths below about 4 micrometers, dropping to near zero at about 6 micrometers.[9] As such, it has applications as a sensor component, specialty IR domes, and windows for laser communications.[9] It has also been demonstrated as an interface passivation layer in some semiconductor-related applications.[10]

Aluminium oxynitride has less than half the weight and thickness of glass-based transparent armor.[11] 1.6-inch (41 mm; 4.1 cm) thick aluminium oxynitride armor is capable of stopping .50 BMG armor-piercing rounds, which can penetrate 3.7 inches (94 mm; 9.4 cm) of traditional glass laminate.[9][12]

In 2005, the United States Air Force began testing aluminium oxynitride-based armor "to shield troops".[13]

Manufacture

Aluminium oxynitride can be fabricated as windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. Its composition can vary slightly: the aluminium content from about 30% to 36%, which has been reported to affect the bulk and shear moduli by only 1–2%.[14] The fabricated greenware is subjected to heat treatment (densification) at elevated temperatures followed by grinding and polishing to transparency. It can withstand temperatures of about 2,100 °C (2,370 K) in inert atmospheres. The grinding and polishing substantially improves the impact resistance and other mechanical properties of armor.[8]

Patents

Patents related to aluminum oxynitride include:

"Transparent aluminum" became a popular term after its use in the film Star Trek IV: The Voyage Home (1986).[15][16]

See also

References
  1. "ALON Optical Ceramic. Technical data" (PDF). Surmet Corporation. 2003. Archived from the original (PDF) on 2013-06-12. Retrieved 2009-01-09.
  2. Mohan Ramisetty et al. Transparent Polycrystalline Spinels Protect and Defend, American Ceramic Society Bulletin, vol.92, 2, 20–24 (2013)
  3. 4520116, Richard L. Gentilman, Edward A. Maguire, Leonard E. Dolhert, "Transparent aluminum oxynitride and method of manufacture", published May 28, 1985, assigned to Surmet Corp
  4. "Domes & Infrared Optics". Surmet.
  5. Ramisetty, Mohan; Sastri, Suri A.; Goldman, Lee (Aug 2013). "Transparent Ceramics Find Wide Use in Optics". Photonics Spectra.
  6. "Surmet Achieves Major Milestone on its ALON Window Scale-up Program". PRWeb. May 28, 2013.
  7. 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.
  8. Joseph M. Wahl et al. Recent Advances in ALON Optical Ceramic, Surmet
  9. Goldman, Lee M.; Twedt, Rich; Balasubramanian, Sreeram; Sastri, Suri (2011-05-20). "ALON optical ceramic transparencies for window, dome, and transparent armor applications". Window and Dome Technologies and Materials XII. SPIE. 8016: 64–77. doi:10.1117/12.886122.
  10. 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. Bibcode:2006ApPhL..89t2903Z. doi:10.1063/1.2388246. Retrieved 2022-02-11.
  11. Security News (2015-06-03). Optically Clear Aluminium Provides Bulletproof Protection. TSS, 3 June 2015. Retrieved on 2015-07-10 from http://www.tssbulletproof.com/optically-clear-aluminum-provides-bulletproof-protection/.
  12. "Surmet's ALON® Transparent Armor 50 Caliber Test". Retrieved 2023-01-09.
  13. Schogol, Jeff (October 30, 2005). "Air Force testing lighter, transparent ALON armor". Stars and Stripes. Retrieved 2020-06-25.
  14. 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.
  15. Harve Bennett, Nicholas Meyer, Steve Meerson, & Peter Krikes (1986). "Screenplay for Star Trek IV: The Voyage Home". Retrieved 2020-02-22.{{cite web}}: CS1 maint: multiple names: authors list (link)
  16. Harve Bennett, Nicholas Meyer, Steve Meerson, & Peter Krikes (1986). "Screenplay for Star Trek IV: The Voyage Home". Retrieved 2020-02-22.{{cite web}}: CS1 maint: multiple names: authors list (link)
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