Aluminium oxynitride

Aluminium oxynitride
Names
Systematic IUPAC name
Aluminium oxynitride
Identifiers
Abbreviations ALON
12633-97-5 Yes
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
Crystal structure cubic spinel
Lattice constant a = 794.6 pm[2]
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 Yes verify (what is: Yes/?)
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-ultraviolet, 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. It can be fabricated to transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. Because of its relatively low 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 bulletproof and blast-resistant windows. Manufacturing methods continue to be refined. The cost is similar to that of synthetic sapphire.

Properties

Mechanical[2]
Thermal and optical[4]

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]

Applications

ALON is used in various defense and infrared- (IR-) related applications such as reconnaissance sensor windows, speciality IR domes with different shapes such as hemispherical, hyper-hemispherical and tangent ogive domes, transparent armor, windows for laser communications, and in some semiconductor-related applications.[2][6] When formed and polished as a window, the material costs from US$10 to US$15 per cm2 (~ US$20,000/m2) for instrument windows 2mm to 5mm thick in large volume (Costs checked 2012).

1.6" thick ALON armor is capable of stopping .50 BMG armor piercing rounds, which can penetrate 3.7" of traditional glass laminate.[7]

Manufacture

ALON is a polycrystalline ceramic material which can be fabricated as windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. It is made primarily of aluminum, oxygen, and nitrogen, and can vary slightly in its composition (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%.[8]) 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 have been 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.

See also

References

  1. ↑ 1.0 1.1 Sales (2003). "ALON Optical Ceramic. Technical data" (.PDF). Surmet Corporation. Retrieved 2009-01-09.
  2. ↑ 2.0 2.1 2.2 2.3 Lee M. Goldman et al. ALON® Optical Ceramic Transparencies for Sensor and Armor Applications, Surmet
  3. ↑ Richard L. Gentilman et al. Transparent aluminum oxynitride and method of manufacture U.S. Patent 4,520,116 Issue date: May 28, 1985
  4. ↑ 4.0 4.1 Joseph M. Wahl et al. Recent Advances in ALONTM Optical Ceramic, Surmet
  5. ↑ 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.
  6. ↑ 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.
  7. ↑ Surmet's ALON® Transparent Armor 50 Caliber Test
  8. ↑ 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.

Patents

External links