Optimization of ceramic strength using elastic gradients

Yu Zhang, Li Ma

Research output: Contribution to journalArticle

Abstract

We present a new concept for strengthening ceramics by utilizing a graded structure with a low elastic modulus at both top and bottom surfaces sandwiching a high-modulus interior. Closed-form equations have been developed for stress analysis of simply supported graded sandwich beams subject to transverse center loads. Theory predicts that suitable modulus gradients at the ceramic surface can effectively reduce and spread the maximum bending stress from the surface into the interior. The magnitude of such stress dissipation is governed by the thickness ratio of the beam to the graded layers. We test our concept by infiltrating both top and bottom surfaces of a strong class of zirconia ceramic with an in-house prepared glass of similar coefficient of thermal expansion and Poisson's ratio to zirconia, producing a controlled modulus gradient at the surface without significant long-range residual stresses. The resultant graded glass/zirconia/glass composite exhibits significantly higher load-bearing capacity than homogeneous zirconia.

Original languageEnglish (US)
Pages (from-to)2721-2729
Number of pages9
JournalActa Materialia
Volume57
Issue number9
DOIs
StatePublished - May 2009

Keywords

  • Ceramic matrix composites (CMC)
  • Flexure formulas
  • Functionally graded materials (FGM)
  • Modulus gradients
  • Stress dissipation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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