Sensors for Harsh Environments by Direct-Write Thermal Spray

Longtin, Jon P.; Sampath, Sanjay; Tankiewicz, S.; Gambino, R. J.; Greenlaw, R.

doi:10.1109/jsen.2003.822218

Cited by 49 publications

(15 citation statements)

References 3 publications

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“…As a result, thermal and kinetic energy is supplied to the particles (Figure 26). This is a similar process to apply TBC to a component [227]. The DWTS process allows the additive generation of sensor circuits on complex shaped components without pre-masking.…”

Section: Hot Gas Component Monitoringmentioning

confidence: 99%

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A Review of NDT/Structural Health Monitoring Techniques for Hot Gas Components in Gas Turbines

Mevissen

Meo

2019

Sensors

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The need for non-destructive testing/structural health monitoring (SHM) is becoming increasingly important for gas turbine manufacturers. Incipient cracks have to be detected before catastrophic events occur. With respect to condition-based maintenance, the complex and expensive parts should be used as long as their performance or integrity is not compromised. In this study, the main failure modes of turbines are reported. In particular, we focus on the turbine blades, turbine vanes and the transition ducts of the combustion chambers. The existing monitoring techniques for these components, with their own particular advantages and disadvantages, are summarised in this review. In addition to the vibrational approach, tip timing technology is the most used technique for blade monitoring. Several sensor types are appropriate for the extreme conditions in a gas turbine, but besides tip timing, other technologies are also very promising for future NDT/SHM applications. For static parts, like turbine vanes and the transition ducts of the combustion chambers, different monitoring possibilities are identified and discussed.

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Section: Hot Gas Component Monitoringmentioning

confidence: 99%

“…K-type thermocouples can measure high operating temperatures. Industry standard K-type thermocouples are made of Chromel (90Ni/10Cr) and Alumel (95Ni/3Mn/2Al/1Si) [227]. A K-type thermocouple consists of a pair of metallic conductors made of these different metals.…”

Section: Hot Gas Component Monitoringmentioning

confidence: 99%

A Review of NDT/Structural Health Monitoring Techniques for Hot Gas Components in Gas Turbines

Mevissen

Meo

2019

Sensors

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“…Direct write is a derivative of thermal spray, which employs a miniature spray torch to print low-profile, fine feature patterns from a wide range of high-temperature materials. Using the direct-write process, a variety of multilayer sensor architectures and printed electronics can be realized with high temperature tolerance for implementation in harsh environments [26][27][28][29]. For the present study, the sensor architecture shown in Fig.…”

Section: B Heat Flux Sensor Fabricationmentioning

confidence: 99%

Heat Flux Measurements in a Scramjet Combustor Using Embedded Direct-Write Sensors

Trelewicz¹,

Longtin²,

Gouldstone

et al. 2015

Journal of Propulsion and Power

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Embedded heat flux sensors fabricated using direct-write technology have been developed and tested within a direct-connect gaseous hydrocarbon-fueled scramjet combustor under Mach 5 flight conditions. The sensors employed a multilayer thermopile architecture fabricated via the additive direct-write thermal spray process, which enables their integration directly onto the components to be tested. The sensors were embedded within a 0.50-mmthick (0.020-in.-thick) thermal barrier coating on test plugs that were inserted into the tunnel for testing. Fuel equivalence ratios and dynamic pressures were varied from φ 0.6 to 1.0 and Q 24 and 48 kPa (500 and 1000 psf), respectively, with increases in the global heat flux found to depend on the tunnel location. Heat flux values ranging from 30 to 75 W∕cm 2 (26 to 66 Btu∕ft 2 · s) were measured downstream of the cavity flame holder, 20 to 150 W∕cm 2 (18 to 132 Btu∕ft 2 · s) in the cavity flame holder, and 20 to 40 W∕cm 2 (18 to 35 Btu∕ft 2 · s) upstream of the flame holder. Direct-write sensors reported heat flux trends that were consistent with separate area-averaged calorimetric measurements, and the local nature of the direct-write sensors enabled the detection of subtle transient phenomena not captured by calorimetry.

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“…Both Theophilou et al [8] and Longtin et al [9] suggested the manufacture of sensors using a traditional thermal spray process which employed masks to pattern the device or by subsequent laser micromachining. Recently, thermal spray techniques, in conjunction with a novel multistage aperture-collimator system, made it possible to deposit sensors with tracks at dimensions of 200 µm directly onto the surface and to be embedded into TBCs, which could survive in harsh environments [10,11]. However, all of the above-mentioned technologies have noticeable disadvantages; all are time-consuming because of either the application of masks or the vacuum-deposition conditions or have an extreme low efficiency of deposition.…”

Section: Introductionmentioning

confidence: 99%

Laser Cladding of Embedded Sensors for Thermal Barrier Coating Applications

et al. 2018

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The accurate real-time monitoring of surface or internal temperatures of thermal barrier coatings (TBCs) in hostile environments presents significant benefits to the efficient and safe operation of gas turbines. A new method for fabricating high-temperature K-type thermocouple sensors on gas turbine engines using coaxial laser cladding technology has been developed. The deposition of the thermocouple sensors was optimized to provide minimal intrusive features to the TBC, which is beneficial for the operational reliability of the protective coatings. Notably, this avoids a melt pool on the TBC surface. Sensors were deposited onto standard yttria-stabilized zirconia (7-8 wt % YSZ) coated substrates; subsequently, they were embedded with second YSZ layers by the Atmospheric Plasma Spray (APS) process. Morphology of cladded thermocouples before and after embedding was optimized in terms of topography and internal homogeneity, respectively. The dimensions of the cladded thermocouple were in the order of 200 microns in thickness and width. The thermal and electrical response of the cladded thermocouple was tested before and after embedding in temperatures ranging from ambient to approximately 450 • C in a furnace. Seebeck coefficients of bared and embedded thermocouples were also calculated correspondingly, and the results were compared to that of a commercial standard K-type thermocouple, which demonstrates that laser cladding is a prospective technology for manufacturing microsensors on the surface of or even embedded into functional coatings.

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Sensors for Harsh Environments by Direct-Write Thermal Spray

Cited by 49 publications

References 3 publications

A Review of NDT/Structural Health Monitoring Techniques for Hot Gas Components in Gas Turbines

A Review of NDT/Structural Health Monitoring Techniques for Hot Gas Components in Gas Turbines

Heat Flux Measurements in a Scramjet Combustor Using Embedded Direct-Write Sensors

Laser Cladding of Embedded Sensors for Thermal Barrier Coating Applications

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