silicon carbide pressure sensors for venus …

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National Aeronautics and Space Administration www.nasa.gov SILICON CARBIDE PRESSURE SENSORS FOR VENUS ENVIRONMENT R. S. Okojie 1 , D. Lukco 2 , R. D. Meredith 1 , L. M. Nakley 1 , and K. Phillips 3 1 NASA Glenn Research Center, Cleveland, OH 44135; [email protected], (216)433-6522 2 Vantage Partners, LLC, NASA Glenn Research Center, Cleveland OH, 3 Sierra Lobo Corporation, NASA Glenn Research Center, Cleveland OH. Primary Sponsor: NASA Transformational Tools and Technologies Project of the ARMD Task Support: Long Life In-Situ Solar System Explorer (LLISSE) of SMD IPPW 2018 Boulder, Colorado

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Page 1: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

SILICON CARBIDE PRESSURE SENSORS FOR

VENUS ENVIRONMENT

R. S. Okojie1, D. Lukco2, R. D. Meredith1, L. M. Nakley1, and K. Phillips3

1NASA Glenn Research Center, Cleveland, OH 44135;

[email protected], (216)433-65222Vantage Partners, LLC, NASA Glenn Research Center, Cleveland OH,

3Sierra Lobo Corporation, NASA Glenn Research Center, Cleveland OH.

Primary Sponsor: NASA Transformational Tools and Technologies Project of the

ARMD

Task Support: Long Life In-Situ Solar System Explorer (LLISSE) of SMD

IPPW 2018 Boulder, Colorado

Page 2: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Interest in Venus has been stimulated by the ongoing debate about

Earth’s planetary evolution, particularly in regards to its climate, and

NASA has proposed a flagship mission to Venus to be launched in the

near future. Quantifying how the Venus evolution ran its course will

greatly aid researchers trying to model Earth’s climate dynamics.

Motivation

ObjectiveTo determine the long-term robustness and survivability of semi-

encapsulated piezoresistive silicon carbide pressure sensors in a simulated

Venus atmosphere where pressure ~90 bar, temperature ~ 465 ⁰C, and

aggressive reactive chemistry (SO2, COS, etc). This is with the goal of

infusion into future Venus science missions

IPPW 2018 Boulder, Colorado

Page 3: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Legacy SiC Pressure Sensors for Aero-Engine Applications

Demonstrated at 800 ⁰C!

3

NASA SiC Pressure Sensors

0

15

30

45

0 50 100 150 200

Net

Ou

tpu

t (m

V)

Applied pressure (psi)

Room 300 ºC 500 ºC 700 ºC 800 ºC

Sensor 273Excitation Voltage = 10V

800 oC Pressure Sensor Demonstrated!Sensor get better with increase in temperature!

Net Output vs. Static Pressure

Approved for public release; distribution unlimited.

Alireza Behbahani and Kenneth Semega, “Sensing challenges for controls and PHM in the hostile operating conditions

of modern turbine engine.” AFRL-RZ-WP-TP-2008-2184

Leverage the superior attributes of

piezoresistive SiC based pressure

sensors at higher temperature:

-Batch fabrication

-Higher gauge factor

-Portability

Tech Leapfrog

Technology Enabling Space

Infusion into Venus missions require material and structural considerations to

survive the chemistry and high pressure

IPPW 2018 Boulder, Colorado

Page 4: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Simulated Venus Atmospheric Conditions

Temperature: 460 ⁰C +/- 10 ⁰C

Pressure: 1356 psia +/- 20 psia

Chemistry: “Venus atmosphere” 96.5% CO2, 3.5% N2, 180 ppm SO2, 12 ppm

CO, 51 ppm COS, 2 ppm H2S, 0.5 ppm HCl, 2.5 ppb HF

Range: SO2 concentration range 100-200 ppm

Glenn Extreme Environment Rig (GEER)

IPPW 2018 Boulder, Colorado

Page 5: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Contact wire

Sealing Glass

Reference Cavity

SiC Pressure Sensor

TC

go

es i

n he

re

AlN

Plug-In Type SiC Absolute Pressure Sensor

IPPW 2018 Boulder, Colorado

Page 6: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Plug-In Type SiC Pressure Sensor Extension for Insertion into GEER

IPPW 2018 Boulder, Colorado

Page 7: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Start Up Vessel leak checked to 1400 psia at ambient temperature with high purity nitrogen.

Next, the vessel will be purged of residual air and nitrogen by performing three

pressure/vacuum cycles. The vessel will be left under vacuum after the last purge

cycle in preparation for the specialty gas fill.

Constituents of Venus atmosphere will be delivered to the vessel at ambient

temperature starting with the vessel at negative pressure. The fill process will begin

with CO2 which will continue to flow continuously as the remaining specialty gas are

filled. Specialty gases will be filled in the following order:

Inlet valve closed to isolate the gas mixture within the vessel. Vessel temperature

set point set to 456 C and the heaters will increase at 7 C/hr until the set point is

reached.

Shutdown Upon completion of test, the vessel temperature set point will be reduced to 150 C. During

cool down, the gas mixture will remain inside the vessel. Once the average gas

temperature reaches 150 C, the mixture will be vented and the vessel will be thoroughly

purged with dry nitrogen. The heaters will maintain an average internal temperature of 150

C during venting and purging. Once the purge is complete, the heaters will be turned off

allowing the vessel to cool to ambient temperature. A small amount of nitrogen will be left

inside the vessel during the final cool down to maintain positive pressure inside the vessel.

GEER Test Conditions

IPPW 2018 Boulder, Colorado

Page 8: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Room Temperature SiC Pressure Response in GEER Chamber(Purge and Vent Steps at room temp)

Sensitivity~0.21 µV/psi

0.44

0.442

0.444

0.446

0.448

0.45

0.452

0 5 10 15 20 25

Ou

tpu

t (V

)

Hours

~1346 psi

14 psi

Nitrogen Venting

Vin=10 VGain=10

0.44

0.442

0.444

0.446

0.448

0.45

0.452

0 2 4 6 8 10 12 14 16 18 20 22

Ou

tpu

t (V

)

Hours

1327 psi 1346 psi

Pressure ramped to 1346 psi and held steady @room (some changes)

Vin=10 VGain=10

0.44

0.442

0.444

0.446

0.448

0.45

0.452

0 1 2 3 4

Ou

tpu

t (V

)

Hours

376 psi

1327 psi

Nitrogen purge. Temperature held relatively steady @ room

Vin=10 VGain=10

Pressure ramp-up Ramp and Dwell Ramp down

1327 psia1327 psia

14 psia

Vin=10 V

Gain=10 Vin=10 V

Gain=10

Vin=10 V

Gain=10

1346 psia ~1346 psia14 psi

IPPW 2018 Boulder, Colorado

Page 9: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

SiC Pressure Sensor Response during GEER Chamber

2.24

2.245

2.25

2.255

2.26

2.265

2.27

0 5 10 15 20 25

Ou

tpu

t (V

)

Hours

Vin=10 VGain=50

Leak check: Pressure Ramp up from 14 psi to 1345 psi @ room

14 psi

1360 psi hold and dwell

2.4 psi

14 psia

2.4 psia

1360 psia hold and dwell

Leak check: Pressure ramp up from 14 psi to 1360 psi @ room

Vin=10 V

Gain=10

Vin=10 V

Gain=50

?

IPPW 2018 Boulder, Colorado

Page 10: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

• Sensor reliably operational for 12 earth days

• Sensor survived 60 earth days (Test duration)

-170

-120

-70

-20

30

80

130

0 100 200 300 400 500 600 700 800 900

Ou

tpu

t (m

V)

Hours

Vin=10 VGain=1

6.7 psi16.9 C

1345 psi451 CReference point

732 psi, 150 C, all gases in;Temperature ramp up to Venus condition

Operational Life of Sensor A

N2 Purge/Temp Ramp Up

Venus condition: 460 C, 1336-1346 psi (SO2 boosting)

SiC Pressure Sensor Operational Life in GEER

IPPW 2018 Boulder, Colorado

Page 11: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Post GEER Chamber Analysis

IPPW 2018 Boulder, Colorado

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National Aeronautics and Space Administration

www.nasa.gov

Post GEER Chamber Analysis

Sensor glass seal

AlN Header

Crystal growth on two adjacent Au wire

AlN back glass seal

Au wire with no crystal growth

Before AfterSensor diaphragm

IPPW 2018 Boulder, Colorado

Page 13: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

• Sealing Glass and sensor remained intact

• AlN header intact

• No loss of reference cavity

Sensor diaphragm

Post GEER Chamber Analysis

Sensor Top View

Glass seal

IPPW 2018 Boulder, Colorado

Page 14: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov 14

Two reaction paths:

1. TiCuSil braze material between ceramic tube and stainless steel tube

• Cu and Ag sulfide crystals grow outward and eventually over the

Au wires terminals.

• Touching of the crystal between wires would result in shunt

resistance.

2. Au-plated Ni wire in individual ceramic tube holes

• Ni diffuses out of Au plating and reacts with SO2 to form nickel

sulfide.

• Continued consumption of the Ni will result in gradual increase

in resistance and sensor output

Key Observations

Inside Chamber Outside Chamber

TiCuSil brazeCeramic tube with Au plated Ni wires SS tube

IPPW 2018 Boulder, Colorado

Page 15: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Devices Materials Outcome

Electronics Packaging Pb PbS

Al2O3 No reaction

Insulation CaO CaSO3, CaSO4

SiC Electronics Pt PtS; fibers when present as thin film

Pt (in the presence of Au) PtS spheres

Au No reaction, but mobile

Ir No reaction, but mobile

SiC No reaction

SiO2 No reaction

Feedthrough Materials Cu Cu2S crystals

Ni NiS crystals

CuBe Cu2S crystals; Cl found on surface

SiC Pressure Sensor Kovar (Ni-Co-Fe) NiS, FexOy

AlN No reaction

Ag-Cu Braze segregation into Cu2S and Ag; Ag mobile

GEER Components Inconel 625 (Ni-Cr-Mo-Fe) NiS, CrxOy

304 SS Mirror finish, low corrosion rate

Al foil/Mg dopedMgO on surface, MgF inner layer,

Al bulk no reaction

Table 4 Tested Materials with Corresponding Outcomes

Lukco, D. et al, Earth and Space Science, doi.org/10.1029/2017EA000355

Materials Tested in Simulated Venus Atmosphere

IPPW 2018 Boulder, Colorado

Page 16: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov

Sensor room temperature test shows good linear response to pressure

Sensor stable and reliably operational for ~12 earth days

Sensor physical structure survived 60 earth days of testing

Primary failure mechanism : Gradual NiS formation on Au-plated Ni

wire resulted in changes in wire resistance

Long term reliable operation beyond 12 days is in the works

Plan to integrate with temperature sensor and electronics in progress

Open to collaboration for infusion into any Venus science mission

architecture

Summary, Conclusion, and Future Plans

IPPW 2018 Boulder, Colorado

Page 17: SILICON CARBIDE PRESSURE SENSORS FOR VENUS …

National Aeronautics and Space Administration

www.nasa.gov 17

Thank You!

IPPW 2018 Boulder, Colorado