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Title: Mesostructure and porosity effects on the thermal conductivity of additively manufactured interpenetrating phase composites

Abstract

In this paper, we have investigated the relationship between structure and thermal conductivity in additively manufactured interpenetrating A356/316L composites. We used X-ray microcomputed tomography to characterize the pore structure in as-fabricated composites, finding microporosity in both constituents as well as a 50 μm thick layer of interfacial porosity separating the constituents. We measured the thermal conductivity of a 43 vol% 316L composite to be 53 Wm -1K -1, which is significantly less than that predicted by a simple rule-of-mixtures approximation, presumably because of the residual porosity. Motivated by these experimental results we used periodic homogenization theory to determine the combined effects of porosity and unit cell structure on the effective thermal conductivity. This analysis showed that in fully dense composites, the topology of the constituents has a weak effect on the thermal conductivity, whereas in composites with interfacial porosity, the size and structure of the unit cell strongly influence the thermal conductivity. Finally, we also found that an approximation formula of the strong contrast expansion method gives excellent estimates of the effective thermal conductivity of these composites, providing a powerful tool for designing functionally graded composites and for identifying mesostructures with optimal thermal conductivity values.

Authors:
 [1];  [2];  [3];  [4];  [5];  [1]
  1. Rice Univ., Houston, TX (United States). Materials Science and NanoEngineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Manufacturing Demonstration Facility
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center; Univ. of Tennessee, Knoxville, TN (United States). Bredesen Center
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rice Univ., Houston, TX (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); Rice Univ. (United States)
OSTI Identifier:
1468211
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Additive Manufacturing
Additional Journal Information:
Journal Volume: 22; Journal ID: ISSN 2214-8604
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; additive manufacturing; composites; thermal conductivity; finite element analysis; homogenization theory

Citation Formats

Moustafa, Abdel R., Dinwiddie, Ralph B., Pawlowski, Alexander E., Splitter, Derek A., Shyam, Amit, and Cordero, Zachary C. Mesostructure and porosity effects on the thermal conductivity of additively manufactured interpenetrating phase composites. United States: N. p., 2018. Web. doi:10.1016/j.addma.2018.05.018.
Moustafa, Abdel R., Dinwiddie, Ralph B., Pawlowski, Alexander E., Splitter, Derek A., Shyam, Amit, & Cordero, Zachary C. Mesostructure and porosity effects on the thermal conductivity of additively manufactured interpenetrating phase composites. United States. doi:10.1016/j.addma.2018.05.018.
Moustafa, Abdel R., Dinwiddie, Ralph B., Pawlowski, Alexander E., Splitter, Derek A., Shyam, Amit, and Cordero, Zachary C. Thu . "Mesostructure and porosity effects on the thermal conductivity of additively manufactured interpenetrating phase composites". United States. doi:10.1016/j.addma.2018.05.018. https://www.osti.gov/servlets/purl/1468211.
@article{osti_1468211,
title = {Mesostructure and porosity effects on the thermal conductivity of additively manufactured interpenetrating phase composites},
author = {Moustafa, Abdel R. and Dinwiddie, Ralph B. and Pawlowski, Alexander E. and Splitter, Derek A. and Shyam, Amit and Cordero, Zachary C.},
abstractNote = {In this paper, we have investigated the relationship between structure and thermal conductivity in additively manufactured interpenetrating A356/316L composites. We used X-ray microcomputed tomography to characterize the pore structure in as-fabricated composites, finding microporosity in both constituents as well as a 50 μm thick layer of interfacial porosity separating the constituents. We measured the thermal conductivity of a 43 vol% 316L composite to be 53 Wm-1K-1, which is significantly less than that predicted by a simple rule-of-mixtures approximation, presumably because of the residual porosity. Motivated by these experimental results we used periodic homogenization theory to determine the combined effects of porosity and unit cell structure on the effective thermal conductivity. This analysis showed that in fully dense composites, the topology of the constituents has a weak effect on the thermal conductivity, whereas in composites with interfacial porosity, the size and structure of the unit cell strongly influence the thermal conductivity. Finally, we also found that an approximation formula of the strong contrast expansion method gives excellent estimates of the effective thermal conductivity of these composites, providing a powerful tool for designing functionally graded composites and for identifying mesostructures with optimal thermal conductivity values.},
doi = {10.1016/j.addma.2018.05.018},
journal = {Additive Manufacturing},
number = ,
volume = 22,
place = {United States},
year = {2018},
month = {5}
}

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