Sintering of hierarchically-structured boron carbide for toughening and multi- functionality
November 10-14, 2019
Boron carbide is light-weight, is thermally stable, has high hardness/stiffness, and is multi-functional (semiconducting, thermoelectric, and high neutron absorption cross-section). Boron carbide has been of interest for applications in extreme environments, including turbine engines, protection armor against impact, heat, and radiation, but such application is currently limited due to its brittleness and low sinterability. The toughening of ceramics has been investigated for many years as a light-weight, thermally/chemically stable alternative to structural materials. Among many methods, ceramic micro-fibers implementation has been effective, and further toughening is expected though engineering of matrices, specifically by implementing intentionally weak interphases to provide locally controlled deformation and thus energy dissipation within matrices. For example, in the past we experimentally studied the potentials of nano-porosity introduction into ceramics on deformation behaviors, by indenting on a model system of anodic aluminum oxide. Normally, porosity in ceramics is regarded as the defect, but we identified that, when pore size is below 100 nm, nanopores deform in a controlled manner (collapse or shear band, see Figure 1a), contributing to fracture toughness increase. Meanwhile, introduction of nano-porosity resulted in stiffness and hardness decrease.
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Namiko Yamamoto, Jingyao Dai, and Jogender Singh, "Sintering of hierarchically-structured boron carbide for toughening and multi- functionality" in "Composites at Lake Louise 2019", John Kieffer, University of Michigan, USA Erik Spoeke, Sandia National Laboratories, USA Meisha Shofner, Georgia Institution of Technology, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/composites_all_2019/1