NASA Technical Reports Server (NTRS) 20050198935: High Temperature Chemistry in the Columbia Accident Investigation

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by  NASA Technical Reports Server (NTRS)

High Temperature Chemistry in the Columbia Accident Investigation
Nathan Jacobson and Elizabeth Opila
NASA Glenn Research Center
Cleveland, OH 44135
David Tallant and Regina Simpson
Sandia National Laboratories
Albuquerque, NM 87 185
Initial estimates on the temperature and conditions of the breach in Columbia’s wing
focused on analyses of the slag deposits. These deposits are complex mixtures of the
reinforced carbodcarbon (RCC) constituents, insulation material, and wing structural
materials. However it was possible to clearly discern meltedsolidified CerachromeB
insulation, indicating the temperatures had exceeded 1760°C. Current research focuses
on the carbodcarbon in the path from the breach. Carbon morphology indicates heavy
oxidation and erosion. Raman spectroscopy yielded further temperature estimates. A
technique developed at Sandia National Laboratories is based on crystallite size in carbon
chars. Lower temperatures yield nanocrystalline graphite; whereas higher temperatures
yield larger graphite crystals. By comparison to standards the temperatures on the
recovered RCC fragments were estimated to have been greater than 2700°C.
High Temperature Chemistry in
u
the Columbia
Y
I
Accident Investigation
Nathan S. Jacobson and Elizabeth J. Opila
NASA Glenn Research Center
Cleveland, OH 44135
David R. Tallant and Regina Simpson
Sandia National Laboratories
Albuquerque, NM 871 85
- Examine @CC)near,breach and hot-gas-path
A
- Understand response of RCC to extreme conditions
- Estimate wing leading edge material temperatures near the
breach+compare to estimates from slag studies
Techniques
- Electron microscropy (Glenn)
r.
- Raman spectroscopy (Sandia)
Identification of Breach
Multi-NASA Center Team Effort-JSC, MSFC, LaRC, GRC
Ish%
Key features o,? f e u edp 62-c
I '
- Large deposits of 'slag'-solidified Cerachrome insulation, aluminum
-
alloys, Fe alloys, Ni alloys ,b-&b;&,
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'~
- 'Knife edge' appearance of RCC (reinforced carbodcarbon)-known to
occur when an exposed edge of RCC is heavily oxidized
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Previous Temperature Estimates
Cerachrome8 mp 1760OC-95% aluminosilicate; 3% chromia
Mullite forms at -1 100°C
Examination slag deposits from upper portion of Panel 8 identified
mullite and melted Cerachrome s 1760OC or greater
I
I
1
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Slag Deposits-Complex Mixtures of Wing Constituents
-
~
i0 SEIL) 04/15/2-003 200um 3 15.0kV 13.Omm X.IO Ok SE(L] 0411512
Region 12 - portion of
Solidified metals and
ceramics carbon fiber
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Region of Melted Cerachrome
Only well-understood Feature for
Temperat ur e Determination
L:!llULL\SHUllL~l \FE-SEMZIW3AlI.SPC
Label A: A3A
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/
~,,~,~~,“.,_N!..~-.. -1 .... . 9 .. . . ., ~ , .
.OO 4.00 6.00 0.00 10.00 12.00 14.00
Label A: AM
I
0
i !
Cr Fe Ni - .
YI---Y-III I-. ~ -,
2.00 4.00 6.00 6.00 10.00 12.00 14.00
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: ‘Slag’ Deposits on&ick Side of
ing Leading Edge
Complex mixture of solidified ceramics, ahminum
s, and nic
Only solidified berachrome gave temperature clues
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Focus on fractured and idized carbon/carbon
-
s some through t
/I?-
,‘ 8 1
/’ //I
,-Sodium Silic
--Short Sic fibers, particles
---SIC (-1.5 mm)
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Location of Carbon Samples
A c
- -
r 1
Reinforced CarbonlCarbon (RCC)
in the Shuttle
-
.I.
I
re
Typical ppearance of RCC Cross Section Fragment
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_-- Inner mold line
_- .
I -.-
Slag-solidified
... ..
. . insulation (Cerachrome)
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Fractured/oxidized carbon
fibers and matrix-Focus
I
1 of this study
Outer mold line
Panel 8--Lower
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