Failure of brittle layers on polymeric substrates from Vickers indentation

Herzl Chai, Brian R. Lawn*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A study is made of median crack evolution in brittle coatings subjected to sharp contacts. A model bilayer system consisting of a glass plate bonded to a polycarbonate base, with a Vickers pyramid as indenter, is used to demonstrate the evolution in situ. The cracks undergo a phase of stable downward growth with increasing load. Beyond the coating mid-plane, flexural stresses (coupled with the local contact field) elongate and accelerate the median cracks through the plate to failure. Critical loads corresponding to this failure state diminish with decreasing layer thickness until, at small thicknesses, failure occurs spontaneously at initiation.

Original languageEnglish
Pages (from-to)335-338
Number of pages4
JournalScripta Materialia
Issue number4
StatePublished - Aug 2006


  • Bilayers
  • Brittle coatings
  • Glass
  • Median cracks
  • Vickers indentation


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