Development of New Thermal Protection Systems Based on - - PowerPoint PPT Presentation

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Development of New Thermal Protection Systems Based on - - PowerPoint PPT Presentation

Jul 01, 2023 541 likes •797 views

Development of New Thermal Protection Systems Based on Polysiloxane/Silica Composites: Properties Characterization I Kurt Schellhase 1 , Robert Brushaber 1,2 , Hao Wu 1 , Joseph H. Koo 1 *, Jarrod Buffy 3 , and Eric Schmid 4 1 The University of

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Development of New Thermal Protection Systems Based on Polysiloxane/Silica Composites: Properties Characterization I

Kurt Schellhase1, Robert Brushaber1,2, Hao Wu1, Joseph H. Koo1*, Jarrod Buffy3, and Eric Schmid4

1The University of Texas at Austin, Dept. of Mechanical Engineering, 204 E. Dean Keeton

St., C2200, Austin, TX 78712

2Texas Research Institute Austin, Inc., 9063 Bee Caves Road, Austin, TX 78733 3Dyna-Glas, 2100 North Wilkinson Way, Perrysburg, OH 43551 4South Dakota School of Mines & Technology, Composites and Polymer Engineering

(CAPE) Laboratory, 501 E. Saint Joseph Street, Rapid City, SD 57701 *Corresponding author: jkoo@mail.utexas.edu

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Today’s Presentation

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  • Background and Motivation
  • Material Systems
  • Characterization Methods
  • Results
  • Conclusion
  • Future Work
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SLIDE 3

Background

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  • Want to investigate new ablative material systems
  • Need for materials which can withstand harsher

environments

  • Rocket Motors
  • TPS Materials for Re-entry Vehicle
  • Nose Cones – Atmospheric Probes
  • Vertical Launching Systems
  • Fire Prevention – Trains, Submarines, etc.
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SLIDE 4

Ablative Materials

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  • Resist thermochemical erosion caused by harsh environment
  • Formation of the protective char layer
  • Different mechanisms for different materials, no one size fits all ablative
  • Current SOTA resins: SC-1008, PT-15
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SLIDE 5

SC-1008

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  • MIL-standard phenolic resole resin manufactured by

Hexion

  • Typically carbon or silica fiber reinforcement
  • Foamed versions of phenolic used for low density ablators
  • Lots of data collected
  • Diverse applications, from TPS materials to rocket motor

materials

  • Relatively cheap
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SLIDE 6

PT-15

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  • Low viscosity cyanate ester (CE) resin manufactured by

Lonza

  • Typically glass reinforcement
  • Different manufacturer, but CE/3D-quartz used as part of

Orion heat shield/compression pad

  • More expensive
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SLIDE 7

DT-1116

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  • Inorganic matrix, utilizing a mixture of polysiloxane

chemistries manufactured Dyna-Glas Technologies LLC

  • Low thermal transfer
  • Excellent chemical resistance
  • Excellent thermal stability
  • Low heat release rate and heat release capacity
  • Low viscosity and cure temperatures
  • Will be examining two proprietary formulations – DT1116-1

and DT-1116-2

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SLIDE 8

Material Characterization

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  • Thermogravimetric Analysis
  • Thermal Stability & Char Yield
  • Microscale Combustion Calorimeter
  • Heat Release Rate and Capacity
  • Kinetic Parameters Modeling
  • Activation Energy
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SLIDE 9

Char Yield Study

  • 1. Dry the TGA sample 150C for 30min
  • 2. Consistent sample size – 20mg
  • 3. TGA heating rate of 20 C/min in nitrogen.
  • 4. Char yield is defined as the %mass

remaining at 1,000 C.

Developed based on a NASA report on PICA

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Char Yield Study

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Char yield results for SC-1008, PT-15, DT1116-1, and DT1116-2.

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SLIDE 11

Char Yield Study

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dTGA for SC-1008, PT-15, DT1116-1, and DT1116-2.

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SLIDE 12

SC-1008 phenolic at heating rates of 5, 10, 20, and 40ºC/min

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SLIDE 13

PT-15 cynate ester at heating rates of 5, 10, 20, and 40ºC/min

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SLIDE 14

DT-1116-1 polysiloxane at heating rates of 5, 10, 20, and 40ºC/min

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SLIDE 15

DT-1116-2 polysiloxane at heating rates of 5, 10, 20, and 40ºC/min

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SLIDE 16

Decomposition temperature (Td) of 10% mass loss temperature

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Weight % at 1,000ºC

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Kinetic Parameters

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  • The rate of thermal decomposition of

polymers can be modeled by the kinetic rate equation

  • Need to have the correct kinetic parameters

in order to have a accurate model

  • Used the isoconversion method to solve for

the kinetic parameters

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SLIDE 18

Kinetic parameters

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  • Due to the multiple stage degradation and the

high residual mass of the polysiloxane resins, the activation energy could not be accurately determined.

  • Model we are using works well with the single

stage, 1st order decomposition

  • Good model for some resins, but gives

nonsensical activation energy values for DT- 1116

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SLIDE 19

Flammability Properties

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  • Microscale Combustion Calorimeter
  • Lab scale for small sizes
  • Screening tool
  • Good alternative to a cone calorimeter
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Flammability Properties

20 Typical heat release curves for the four resin systems

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SLIDE 21

Flammability Properties

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Comparison of the Heat Release Capacities for the four resin systems

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SLIDE 22
  • DT-1116-1 exhibited the best results with 87% char
  • yield. An increase of ~54% compared to phenolic and

cyanate ester resins.

  • DT-1116 had a HRC of 36 J/g-K. SC-1008 phenolic’s

HRC was 48% higher at 53.31 J/g-K and PT-15 cyanate ester’s HRC was 443% higher at 159.33 J/g-K

  • Activation energy could not be accurately determined

with the current models. A better model is needed.

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Conclusion

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SLIDE 23
  • Dispersion of nanosilica into the resin, and additional

characterization

  • Incorporation of silica fabric into the polysiloxane resin
  • Ablation testing using Oxygen-Acetylene Test Bed

(OTB) and Inductively Coupled Plasma (ICP) torch

  • Mechanical properties

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Future Work

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SLIDE 24

Questions?