Abstract
The high-temperature oxidation of additively manufactured and chemically vapor infiltrated (3D-printed SiC) has been compared to chemical vapor deposited (CVD) SiC. 100-h isothermal exposures were conducted at 1425° and 1300°C at 1 atm under both dry air and steam environments. A SiC reaction tube was utilized to reduce silica volatility. After steam oxidation at 1425° and 1300°C, on the 3D-printed SiC surface, which was intrinsically rougher than the CVD surface, scales were 70%–90% thicker at the convex regions compared to concave/flat regions. In the convex regions, large cracks perpendicular to the oxidizing interface were observed. After dry air oxidation, scale thicknesses were comparable between 3D-printed SiC and CVD SiC, regardless of geometry. Finite element modeling, conducted to elucidate the relationship between SiC geometry and ß- to α-cristobalite transformation stress, determined cristobalite transformation tensile stresses to be on the order of 103 MPa during cool down, assuming a 6 vol% reduction. Compared to flat SiC substrates, tensile transformation stresses were elevated at concave regions and relaxed at convex regions. Combined with specimen mass gain (accounting for the rougher surface) of 3D-printed SiC being 15%–32% higher for 3D-printed SiC after 1300°C and 1425°C steam oxidation, the work presented concludes that the increased oxidation of 3D-printed SiC is primarily caused by tensile hoop stresses driven by oxidation volume expansion. Lastly, the efficacy of the 3D-printing method is demonstrated through the production of tristructural isotropic imbedded 3D-printed SiC fuel forms.
| Original language | English |
|---|---|
| Pages (from-to) | 2225-2237 |
| Number of pages | 13 |
| Journal | Journal of the American Ceramic Society |
| Volume | 104 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 2021 |
Funding
The oxidation and modeling work at ORNL was sponsored by the Transformational Challenge Reactor program under auspices of US Department of Energy, Office of Nuclear Energy. The University of Texas at San Antonio (UTSA) effort on this investigation was supported by the US Department of Energy Office of Nuclear Energy Advanced Gas Reactor Program and Department of Energy Nuclear Energy University Programs, award number: DE‐NE0008798. The aid and technical insight of Bruce Pint, Brandon Johnston, and Mike Howell are gratefully acknowledged. Sebastien Dryepondt and Takaaki Koyanagi performed a thorough review of the manuscript. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency express or implied or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
| Funders | Funder number |
|---|---|
| DOE Office of Nuclear Energy | DE‐NE0008798 |
| US Department of Energy Office of Nuclear Energy Advanced Gas Reactor Program | |
| U.S. Department of Energy | |
| Office of Nuclear Energy | |
| University of Texas at San Antonio |
Keywords
- modeling/model
- oxidation
- silicon carbide
