Scale up of large ALON<sup>®</sup> and spinel windows

Goldman, Lee M.; Kashalikar, Uday; Ramisetty, Mohan; Jha, Santosh Kumar; Sastri, Suri

doi:10.1117/12.2269467

Cited by 4 publications

(3 citation statements)

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“…The material can achieve excellent transmittance from ultraviolet to mid-infrared wavelengths [ 3 ]. These ceramics have various favorable properties, such as good mechanical strength, temperature stability, and chemical resistance, that allow them to be applied as transparent armor, missile domes, refractory materials, optoelectronics, and high temperature windows [ 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

2021

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This paper describes combusting loose powder beds of mixtures of aluminum metal powders and aluminum oxide powders with various grain sizes under various nitrogen pressure. The synthesis conditions required at least 20/80 weight ratio of aluminum metal powder to alumina powder in the mix to reach approximately 80 wt% of γ-AlON in the products. Finely ground fused white alumina with a mean grain size of 5 μm was sufficient to achieve results similar to very fine alumina with 0.3 μm grains. A lower nitrogen pressure of 1 MPa provided good results, allowing a less robust apparatus to be used. The salt-assisted combustion synthesis upon addition of 10 wt% of ammonium nitrite resulted in a slight increase in product yield and allowed lower aluminum metal powder content in mixes to be ignited. Increasing the charge mass five times resulted in a very similar γ-AlON yield, providing a promising technology for scaling up. Synthesis in loose powder beds could be utilized for effective production of relatively cheap and uniform AlON powder, which could be easily prepared for forming and sintering without intensive grounding and milling, which usually introduce serious contamination.

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Section: Introductionmentioning

confidence: 99%

Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

2021

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“…8,9 AlON transparent windows have been scaled up to 14 × 24 inches and even larger sizes. 10 AlON transparent ceramics have a good light transmittance in the wavelength range of 0.2-5.2 μm, as well as excellent mechanical and dielectric properties, making it a candidate material for IR windows, metal vapor lamp envelopes, and opt-electric windows. [11][12][13] AlON ceramics are regarded as durable optical materials used in high-temperature applications due to their structural stability.…”

Section: Introductionmentioning

confidence: 99%

“…Over decades, Raytheon produced large‐sized transparent ceramics of high optical quality and commercialized transparent ceramics 8,9 . AlON transparent windows have been scaled up to 14 × 24 inches and even larger sizes 10 . AlON transparent ceramics have a good light transmittance in the wavelength range of 0.2‐5.2 μm, as well as excellent mechanical and dielectric properties, making it a candidate material for IR windows, metal vapor lamp envelopes, and opt‐electric windows 11‐13 .…”

Section: Introductionmentioning

confidence: 99%

Oxidation behavior and mechanism of aluminum oxynitride (AlON) at elevated temperatures

Yang

Chen

et al. 2020

J. Am. Ceram. Soc.

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The oxidation behavior and mechanism of aluminum oxynitride (AlON) powder exposed to air at elevated temperatures between 800°C and 1300°C was investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM), electron spin resonance (ESR), nuclear magnetic resonance (NMR), and simultaneous thermogravimetry, differential thermal analysis, and mass spectrometry techniques (TG-DTA-MS). The weight of AlON gradually increases to a maximum value at 1150°C and then decreases with further heating. Meanwhile, AlON powder undergoes chemical changes, as evidenced by lattice expansion, and turns eventually into alumina. ESR spectra reveal the occurrence of lone pair electrons in the oxidized products and the intensity of corresponding resonance signal increases before disappearing with the increase in temperature. Combined with the results of NMR and TG-DTA-MS, the measured data suggest that Al-N in [AlO 3 N] tetrahedron and [AlO 5 N] octahedron are gradually oxidized into Al-ON group with lone pair electrons, which causes continuous weight gain and lattice expansion. Further oxidation at higher temperatures results in alumina and N 2 .

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Research status and challenges in the manufacturing of IR conformal optics

Zhao,

Wang,

Zhang

et al. 2024

Defence Technology

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Scale up of large ALON^® and spinel windows

Cited by 4 publications

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Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

Oxidation behavior and mechanism of aluminum oxynitride (AlON) at elevated temperatures

Research status and challenges in the manufacturing of IR conformal optics

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Scale up of large ALON® and spinel windows

Cited by 4 publications

References 0 publications

Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

Oxidation behavior and mechanism of aluminum oxynitride (AlON) at elevated temperatures

Research status and challenges in the manufacturing of IR conformal optics

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Product

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Scale up of large ALON^® and spinel windows