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Published September 2013 | public
Journal Article

Impact of doping on the mechanical properties of acicular mullite

Abstract

Acicular mullite (ACM) is a highly porous ceramic with a needlelike microstructure. Next-generation ACM-based diesel particulate filters will require porosities >60%, making optimizing ACM's mechanical properties a key area of interest. A prior study determined that, for the range of microstructures evaluated, the elastic modulus, strength, and fracture toughness were largely functions of total porosity and not needle or pore size, consistent with the Gibson–Ashby foam model. Therefore, alternate strengthening and toughening methods were sought. Doping the ACM precursor with either MgO or Nd_2O_3 produced ACM microstructures that appeared similar but had differing bulk mechanical properties. The mechanical properties of the mullite needles, the intergranular glassy phase, and the mullite–glass interface of the ACMs were investigated, but no major differences were found. Using X-ray computed tomography, a 3D imaging technique, it was found that MgO-doping of the ACM created a less uniform, and thus weaker, microstructure than Nd_2O_3-doping.

Additional Information

© 2013 Elsevier Ltd. Received 13 October 2012; received in revised form 21 January 2013; accepted 5 February 2013; Available online 9 March 2013. This work was funded by a research grant from The Dow Chemical Company. ACM processing and portions of the SEM microscopy were carried out at The Dow Chemical Company, and the authors would like to thank Kwanho Yang, Chan Han, Cliff Todd, Janet Goss, Sherry Allen, and Nick Shinkel from Core R&D of The Dow Chemical Company for their help and expertise. The mechanical property tests were done at the CLAMMP facility at Northwestern University (NSF DMR-0520513). Additional SEM microscopy was performed in the EPIC and Keck-II facilities of NUANCE at Northwestern University. NUANCE Center is supported by NSF-NSEC, NSF-MRSEC, Keck Foundation, the State of Illinois, and Northwestern University. Test sample preparation was carried out at the OMM facility of Northwestern University. X-ray computed tomography was done at the Advanced Photon Source. Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. Finally, a special thanks to David Haberthür and Julie Fife for their help and training in 3D image analysis.

Additional details

Created:
August 22, 2023
Modified:
October 26, 2023