The effect of annealing, precipitation-strengthening, and compressive coating processes on sapphire strength

Liu, C.M.; Chen, J.C.; Hu, Long

doi:10.1016/j.msea.2006.01.051

Cited by 11 publications

(8 citation statements)

References 12 publications

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“…The higher the wavenumbers, the lower the absorption coefficients; therefore, the infrared transmittance in the short-wavelength region is less influenced by temperature. The infrared absorption close to the cutoff wavelengths is enhanced, which is seen by the decrease of the high-temperature transmittance and the blue shift of the cutoff wavelengths . With increasing testing temperature, the intensified phonon vibrations increase the density of the maximum phonon energy of the IR material.…”

Section: Resultsmentioning

confidence: 99%

“…The infrared absorption close to the cutoff wavelengths is enhanced, which is seen by the decrease of the high-temperature transmittance and the blue shift of the cutoff wavelengths. 3 With increasing testing temperature, the intensified phonon vibrations increase the density of the maximum phonon energy of the IR material. The higher the maximum phonon energy, the shorter the cutoff wavelength of the infrared spectrum.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Progress in the preparation of large-sized sapphire (α-Al 2 O 3 single crystal) with high quality makes it an attractive infrared (IR)-transmission window candidate material. − However, in extreme military, metallurgy, and aerospace environments, sapphire windows may face further challenges such as harsh climates, flying sand, thermal shock, and high-power laser. Therefore, many issues should be considered for their practical application.…”

Section: Introductionmentioning

confidence: 99%

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SiO₂/HfO₂ Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

Zhao

Wang

et al. 2021

ACS Appl. Electron. Mater.

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It is indispensable to achieve antireflection and protection of the sapphire (i.e., Al 2 O 3 single crystal) infrared window, especially in extreme environments such as high temperature and highenergy laser irradiation. Here, double-layered SiO 2 /HfO 2 films were deposited on sapphire by RF magnetron sputtering with subsequent annealing. The annealing of HfO 2 films in pure oxygen facilitates crystallization, as well as an obvious increase of the O/Hf ratio. The influences of the HfO 2 interlayer on the film microstructure, adhesive strength, film stress, laser-damage resistance, flexure strength, and infrared (IR) transmittance at various temperatures were investigated. The introduction of the HfO 2 interlayer leads to the densification of the SiO 2 protective layer, an improvement in adhesive strength, and an apparent reduction in film stress. A higher flexure strength at high temperature is observed for sapphire coated with a SiO 2 film, while the double-layer SiO 2 (670 nm)/HfO 2 (650 nm) film is superior to the single-layer SiO 2 film in terms of IR high-temperature transmittance and laser-damage resistance.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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SiO₂/HfO₂ Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

Zhao

Wang

et al. 2021

ACS Appl. Electron. Mater.

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“…The existing methods for the strengthening of singlecrystal ceramics are solid solution [3] or precipitation strengthening [4], coating [5], and neutron irradiation [6]. Nevertheless, a surface layer of solid solution or precipitation changes the chemical composition of single crystals, which also results in a decrease of optical transmittance [4]. Neutron irradiation causes transmutation of elements into radioactive isotopes that can pose a hazard to people.…”

Section: Introductionmentioning

confidence: 99%

Surface strengthening of single-crystal alumina by high-temperature laser shock peening

Wang

Yan

Liu

et al. 2020

Materials Research Letters

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“…3 Annealing effects on sapphire have also been studied. 4 Sapphire's material properties creates a unique opportunity for high temperature pressure sensing; however, its high strength, large hardness, and chemical resistance also renders most of the MEMS manufacturing techniques used for sensor fabrication impractical. Laser machining has been proven effective to machine ceramics recently.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Laser Machining of Sapphire for High Temperature Pressure Transducers

Bal¹,

Oates²,

Kumar³

et al. 2016

57th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Challenges associated with materials for high temperature pressure sensor designs, in excess of 1000 • C, are explored here for future applications such as control of combustion processes and flow control of hypersonic vehicles. Currently, silicon based MEMS technology is primarily used for pressure sensing. However, due to the limited melting point of silicon, such sensors have a limited temperature range of approximately 600 • C which is capable of being pushed towards 1000 • C with active cooling. To overcome thermal limitations, the thermomechanical properties of sapphire are investigated to facilitate the design of an optical based pressure transducer which is designed to operate at temperatures approaching 1600 • C. Due to sapphire's hardness and chemical inertness, traditional cutting and etching methods used in MEMS technology are not applicable. The proposed methodology for the sapphire based sensing technology is picosecond laser machining. Here we summarize the material property changes that occur from laser machining across temperatures ranging from room temperature to 1300 • C. Both changes in elastic moduli and strength, as functions of laser machining and temperature, are quantified using four-point bending experiments. The results illustrate comparable or improved strength after laser machining while the modulus was reduced after laser machining at room temperature and 1300 • C by a factor of 1.5 to 2.0.

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The effect of annealing, precipitation-strengthening, and compressive coating processes on sapphire strength

Cited by 11 publications

References 12 publications

SiO₂/HfO₂ Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

SiO₂/HfO₂ Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

Surface strengthening of single-crystal alumina by high-temperature laser shock peening

Experimental Investigation of Laser Machining of Sapphire for High Temperature Pressure Transducers

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The effect of annealing, precipitation-strengthening, and compressive coating processes on sapphire strength

Cited by 11 publications

References 12 publications

SiO2/HfO2 Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

SiO2/HfO2 Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

Surface strengthening of single-crystal alumina by high-temperature laser shock peening

Experimental Investigation of Laser Machining of Sapphire for High Temperature Pressure Transducers

Contact Info

Product

Resources

About

SiO₂/HfO₂ Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures

SiO₂/HfO₂ Laser Film with Enhanced Protection and Antireflection for Sapphire Infrared Windows at High Temperatures