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 mid-wave-infrared regions of the electromagnetic spectrum. It is four times as hard as fused silicaglass, 85% as hard as sapphire, and nearly 115% as hard as magnesium aluminate spinel. It can be fabricated into transparent windows, plates, domes, rods, tubes, and other forms using conventional ceramic powder processing techniques.[citation needed]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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]
Propertiesedit
Aluminium oxynitride is resistant to various acids, bases, and water.[6]
Mechanicaledit
Aluminium oxynitride has the following mechanical properties:[2]
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.[8] It has also been demonstrated as an interface passivation layer in some semiconductor-related applications.[9]
Aluminium oxynitride has less than half the weight and thickness of glass-based transparent armor.[10] Aluminium oxynitride armor of 1.6-inch (41 mm; 4.1 cm) thickness is capable of stopping .50 BMG armor-piercing rounds, which can penetrate 3.7 inches (94 mm; 9.4 cm) of traditional glass laminate.[8][11]
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%.[13] 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.[7]
Patentsedit
Patents related to aluminium oxynitride include:
Aluminium oxynitride having improved optical characteristics and method of manufacture TM Hartnett, RL Gentilman U.S. patent 4,481,300, 1984
Process for producing polycrystalline cubic aluminium oxynitride JW McCauley U.S. patent 4,241,000, 1980
Transparent aluminium oxynitride and method of manufacture RL Gentilman, EA Maguire U.S. patent 4,520,116, 1985; U.S. patent 4,720,362, 1988
^ ab"ALON Optical Ceramic. Technical data" (PDF). Surmet Corporation. 2003. Archived from the original (PDF) on 2013-06-12. Retrieved 2009-01-09.
^ abcdMohan Ramisetty et al. Transparent Polycrystalline Spinels Protect and Defend, American Ceramic Society Bulletin, vol.92, 2, 20–24 (2013)
^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
^Ramisetty, Mohan; Sastri, Suri A.; Goldman, Lee (Aug 2013). "Transparent Ceramics Find Wide Use in Optics". Photonics Spectra.
^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.
^ abJoseph M. Wahl et al. Recent Advances in ALON Optical Ceramic, Surmet
^ abGoldman, Lee M.; Twedt, Rich; Balasubramanian, Sreeram; Sastri, Suri (2011-05-20). Tustison, Randal W. (ed.). "ALON optical ceramic transparencies for window, dome, and transparent armor applications". Window and Dome Technologies and Materials XII. 8016. SPIE: 64–77. Bibcode:2011SPIE.8016E..08G. doi:10.1117/12.886122. S2CID 123044722.
^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/ Archived 2018-02-21 at the Wayback Machine.
^Schogol, Jeff (October 30, 2005). "Air Force testing lighter, transparent ALON armor". Stars and Stripes. Retrieved 2020-06-25.
^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.
External linksedit
Processing of Optically Transparent Aluminum Oxynitride
"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.
The Influence of Sintering Additives on the Microstructure and Properties of ALON. Yechezkel Ashuach. Master's Thesis, Technion – Israel Institute of Technology, 2003.