Microstructure characterization of electric field assisted sintering (EFAS) sintered metallic and ceramic materials using local thermal diffusivity measurement

• Published in: AIP advances Vol. 13; no. 9; pp. 095220 - 095220-7
• Main Authors: Hua, Zilong, Merighe, Patrick, Rufner, Jorgen, Preston, Arin, Schley, Robert, Wang, Yuzhou, Doran, Spencer, Hurley, David
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 01.09.2023; American Institute of Physics (AIP); AIP Publishing LLC
• Subjects: Diffusivity; electric field assisted sintering; Electric fields; Energy consumption; Heating rate; local density measurement; MATERIALS SCIENCE; Microstructure; Percolation; Plasma sintering; Porosity; Sintering (powder metallurgy); Spark plasma sintering; Surface preparation; Thermal diffusivity
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/5.0160625

Electric Field Assisted Sintering (EFAS, also referred to as spark plasma sintering) is a powerful technology for the consolidation of powder materials. The high heating rate during the sintering process is critical for minimizing energy consumption, but it can also cause microstructure heterogeneities in sintered parts, such as spatially varied porosity. The examination of localized porosity usually requires the use of a scanning electron microscope with a carefully prepared surface. In this paper, photothermal radiometry is used to measure local thermal diffusivity and extract localized porosity of EFAS-sintered parts by using a percolation-threshold model. Applying this approach, we identified the radial position-dependent porosity variation in EFAS parts, which is likely formed due to the large temperature gradient during the sintering process. This approach has a unique advantage because it can measure samples with minimal or no surface preparation, enabling the possibility of in situ characterization in EFAS with proper system modification. Necessary modifications on the measurement approach for EFAS deployment and in situ characterization are also discussed.