Abstract
Silica fiber optic sensors are resistant to corrosive environments and high temperatures, making them attractive candidates for harsh conditions found in nuclear and aerospace industries. Moreover, fibers can be deployed remotely for continuous measuring of spatially distributed temperatures and strains. This study investigated embedding a Ni/Cu bi-metallic coated fiber in a stainless-steel 316 (SS316) matrix using laser powder bed fusion towards functionalizing metal components for site-specific health monitoring. The embedded fiber was continuously interrogated during controlled heating to 1000°C. The measured fiber strains were similar to the expected differential thermal strains between the fiber and the SS316 matrix, until divergent behavior was observed at temperatures >500°C. No debonding at the matrix–coating–fiber interfaces was observed during microscopy, but significant interactions between the coatings and matrix resulted in diffusion-driven chemistry variations and Kirkendall void formation. Applying the strain-lag theory revealed plastic behavior in the Ni coating at temperatures >500°C, limiting the strain transfer to the fiber at higher temperatures. It was estimated that the elastic modulus in the Ni coating had decreased from ∼200 GPa at room temperature to below 40 GPa, starting at 600°C. The low elastic modulus above 600°C is within the margin of what the tangent modulus would be in the case of bilinear isotropic hardening. Regardless of the divergent strain transfer at higher temperatures, the fiber was exposed to the equivalent of 1.9 % engineering strain at 1000°C, but measured only a 0.7 % engineering strain due to the poor strain transfer. Although compensating for the plastic behavior of Ni proved challenging, the bonding of a brittle silica fiber to a metal matrix surviving to 1000°C invites potential iterations on coating material for future application. For example, the embedded fiber is sufficient for acoustic energy transfer, realizing high temperature distributed acoustic sensing.
| Original language | English |
|---|---|
| Article number | 104355 |
| Journal | Additive Manufacturing |
| Volume | 91 |
| DOIs | |
| State | Published - Jul 5 2024 |
Funding
Notice: This manuscript has been authored by UT-Battelle, LLC under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This work was originally supported by the Transformational Challenge Reactor Program and later supported by the Advanced Materials and Manufacturing Technologies Program of the US Department of Energy’s Office of Nuclear Energy. Electroplating of the Ni coating was performed by Cesar Dominguez at Los Alamos National Laboratory. FIB in situ lift-out was performed by Yi-Feng Su. Spectroscopy was performed by Will Cureton and Robert Sacci. The authors thank Daniel C. Sweeney and Gerry L. Knapp for their insightful reviews of the draft manuscript. This work was originally supported by the Transformational Challenge Reactor Program and later supported by the Advanced Materials and Manufacturing Technologies Program of the US Department of Energy's Office of Nuclear Energy. Electroplating of the Ni coating was performed by Cesar Dominguez at Los Alamos National Laboratory. FIB in situ lift-out was performed by Yi-Feng Su. Spectroscopy was performed by Will Cureton and Robert Sacci. The authors thank Daniel C. Sweeney and Gerry L. Knapp for their insightful reviews of the draft manuscript.
Keywords
- Additive manufacturing
- Distributed sensing
- Laser powder bed fusion
- Optical frequency domain reflectometry
- SS316