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This content will become publicly available on December 27, 2018

Title: Effect of silicon and oxygen dopants on the stability of hydrogenated amorphous carbon under harsh environmental conditions

Harsh environments pose materials durability challenges across the automotive, aerospace, and manufacturing sectors, and beyond. While amorphous carbon materials have been used as coatings in many environmentally-demanding applications owing to their unique mechanical, electrical, and optical properties, their limited thermal stability and high reactivity in oxidizing environments have impeded their use in many technologies. Silicon- and oxygen-containing hydrogenated amorphous carbon (a-C:H:Si:O) films are promising for several applications because of their higher thermal stability and lower residual stress compared to hydrogenated amorphous carbon (a-C:H). However, an understanding of their superior thermo-oxidative stability compared to a-C:H is lacking, as it has been inhibited by the intrinsic challenge of characterizing an amorphous, multi-component material. Here, we show that introducing silicon and oxygen in a-C:H slightly enhances the thermal stability in vacuum, but tremendously increases the thermo-oxidative stability and the resistance to degradation upon exposure to the harsh conditions of low Earth orbit (LEO). The latter is demonstrated by having mounted samples of a-C:H:Si:O on the exterior of the International Space Station via the Materials International Space Station (MISSE) mission 7b. Exposing lightly-doped a-C:H:Si:O to elevated temperatures under aerobic conditions or to LEO causes carbon volatilization in the near-surface region, producing a silica surfacemore » layer that protects the underlying carbon from further removal. In conclusion, these findings provide a novel physically-based understanding of the superior stability of a-C:H:Si:O in harsh environments compared to a-C:H.« less
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [4] ;  [5] ;  [6] ;  [5] ;  [4] ;  [7] ;  [4]
  1. Univ. of Texas, Austin, TX (United States)
  2. Lehigh Univ., Bethlehem, PA (United States)
  3. Univ. of Pittsburgh, PA (United States)
  4. Univ. of Pennsylvania, Philadelphia, PA (United States)
  5. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  6. Univ. of North Texas, Denton, TX (United States)
  7. Univ. of Florida, Gainesville, FL (United States)
Publication Date:
Report Number(s):
SAND-2017-11747J
Journal ID: ISSN 0008-6223; 658425
Grant/Contract Number:
AC04-94AL85000; AC02-98CH10886
Type:
Accepted Manuscript
Journal Name:
Carbon
Additional Journal Information:
Journal Volume: 130; Journal Issue: C; Journal ID: ISSN 0008-6223
Publisher:
Elsevier
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1429674