<title>Micromachined SiC fiber optic pressure sensors for high-temperature aerospace applications</title>

An analytical review of physically possible methods and available achievements in registering hydrostatic pressure or mechanical stresses using fiber optic fibers and sensors based on them based on published works that can be used in harsh environmental conditions is carried out. The results of the review show that fully distributed or quasidistributed fiber-optic systems for recording hydrostatic pressure or mechanical stress can be implemented on the following physical principles and apparatus with measures to compensate or suppress the influence of temperature: polarizing sensors on birefringent single- mode light guides and OTDR equipment; micro-flexible sensors with OTDR equipment on conventional multimode fibers; measuring systems on fiber Bragg gratings; on discrete sensors, in particular, on sealed fiber Fabry–Perot interferometers; Brillouin distributed sensors on single-mode fibers that are not sensitive to temperature changes. It is shown that single-mode birefringent fibers with hollow holes in the shell and fiber Bragg gratings written in the core have a good linear sensitivity to hydrostatic pressure and a weak dependence on temperature. Lattices in phosphorous-containing single-mode light guides have increased high-temperature properties up to ~500 C and higher. A number of discrete fiber sensors’ structures and pressure recorders are investigated. Various structures of sensitive elements of pressure sensors on sealed fiber Fabry–Perot interferometers and fiber gratings in spherical and cylindrical small-sized cases are investigated. Sensors based on Fabry–Perot fiber interferometers soldered into a glass capillary and protected from water by external high-temperature hermetic coatings showed good linearity in the pressure range of 0…540 ATM at temperatures up to ~200 C. The sensors are efficient at temperatures up to 600 °C and are promising for use in severe and special external conditions. The possibility of compensating the temperature sensitivity by selecting external coatings is shown. Pressure sensors were tested on local areas with microbends and it was shown that they can measure pressures up to ~24 МPа at temperatures up to ~450 C, but to compensate for the dependence of the readings on temperature, it must be measured by an independent sensor. The possibility of independent and simultaneous measurement of hydrostatic pressure and temperature along a single fiber using spontaneous Brillouin scattering is shown. Pressure is measured by the frequency shift of Brillouin scattering, and temperature by its intensity. The operation of the Brillouin recorder in the pressure range 0…34 MРа is demonstrated. The pressure resolution was ~0,2 МРа. New methods are proposed for detecting Brillouin scattering – a heterodyne signal with a high signal-to-noise ratio and based on frequency modulation of a semiconductor single-frequency distributed feedback laser. The measurement range has been increased by more than 10 km and the coordinate resolution has been increased. The Brillouin scattering method is promising for creating distributed systems for measuring hydrostatic pressure or mechanical stress for severe physical conditions, including temperatures of ≥3000 C.

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All-SiC Fiber-Optic Sensor Based on Direct Wafer Bonding for High Temperature Pressure Sensing

Photonic Sensors ◽

10.1007/s13320-021-0640-7 ◽

2021 ◽

Author(s):

Ting Liang ◽

Wangwang Li ◽

Cheng Lei ◽

Yongwei Li ◽

Zhiqiang Li ◽

...

Keyword(s):

High Temperature ◽

Pressure Sensor ◽

Fiber Optic ◽

Fiber Optic Sensor ◽

Sensor Failure ◽

Light Interference ◽

Sic Fiber ◽

Direct Wafer Bonding ◽

Bonding Technology ◽

Sic Wafer

AbstractThis paper presents an all-SiC fiber-optic Fabry-Perot (FP) pressure sensor based on the hydrophilic direct bonding technology for the applications in the harsh environment. The operating principle, fabrication, interface characteristics, and pressure response test of the proposed all-SiC pressure sensor are discussed. The FP cavity is formed by hermetically direct bonding of two-layer SiC wafers, including a thinned SiC diaphragm and a SiC wafer with an etched cavity. White light interference is used for the detection and demodulation of the sensor pressure signals. Experimental results demonstrate the sensing capabilities for the pressure range up to 800 kPa. The all-SiC structure without any intermediate layer can avoid the sensor failure caused by the thermal expansion coefficient mismatch and therefore has a great potential for pressure measurement in high temperature environments.

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TEM study of boron additions to cobalt aluminide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104790 ◽

1988 ◽

Vol 46 ◽

pp. 546-547

Author(s):

Gerald B. Feldewerth

Keyword(s):

High Temperature ◽

Turbine Engines ◽

Major Drawback ◽

University Of Missouri ◽

Specific Strength ◽

Aerospace Applications ◽

Wide Range ◽

Ordered Alloys ◽

The University ◽

Very High

In recent years an increasing emphasis has been placed on the study of high temperature intermetallic compounds for possible aerospace applications. One group of interest is the B2 aiuminides. This group of intermetaliics has a very high melting temperature, good high temperature, and excellent specific strength. These qualities make it a candidate for applications such as turbine engines. The B2 aiuminides exist over a wide range of compositions and also have a large solubility for third element substitutional additions, which may allow alloying additions to overcome their major drawback, their brittle nature.One B2 aluminide currently being studied is cobalt aluminide. Optical microscopy of CoAl alloys produced at the University of Missouri-Rolla showed a dramatic decrease in the grain size which affects the yield strength and flow stress of long range ordered alloys, and a change in the grain shape with the addition of 0.5 % boron.

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Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121193 ◽

1992 ◽

Vol 50 (1) ◽

pp. 158-159

Author(s):

Warren J. Moberly ◽

Daniel B. Miracle ◽

S. Krishnamurthy

Keyword(s):

Thermal Stresses ◽

Load Transfer ◽

Coefficient Of Thermal Expansion ◽

Hot Isostatic Pressing ◽

Matrix Composites ◽

Ongoing Research ◽

Aerospace Applications ◽

Sic Fiber ◽

The Matrix ◽

Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

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Application of fiber optic high temperature sensors for structural monitoring of structures submitted to fire

IABSE Symposium Report ◽

10.2749/222137814814069598 ◽

2014 ◽

Vol 102 (7) ◽

pp. 2932-2938 ◽

Cited By ~ 1

Author(s):

Paula Rinaudo ◽

Benjamín Torres Górriz ◽

David Barrera Villar ◽

Ignacio Payá Zaforteza ◽

Pedro Calderon Garcia ◽

...

Keyword(s):

High Temperature ◽

Fiber Optic ◽

Temperature Sensors ◽

Structural Monitoring

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ALCOA ALUMINUM ALLOY 7050

Alloy Digest ◽

10.31399/asm.ad.al0233 ◽

1990 ◽

Vol 39 (1) ◽

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

High Temperature ◽

Magnesium Alloy ◽

Stress Corrosion Cracking ◽

Heat Treating ◽

Thin Sections ◽

Aerospace Applications ◽

Temperature Performance ◽

Aluminum Company

Abstract ALCOA ALUMINUM ALLOY 7050 is an aluminum-zinc-copper-magnesium alloy with a superior combination of strength, stress-corrosion cracking resistance and toughness, particularly in thick sections. In thin sections it also possesses an excellent combination of properties that are important for aerospace applications. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, and joining. Filing Code: Al-233. Producer or source: Aluminum Company of America. Originally published as Aluminum 7050, January 1979, revised January 1990.

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