Cracking of brittle coatings adhesively bonded to substrates of unlike modulus

Kee Sung Lee, Young Woo Rhee, Douglas H. Blackburn, Brian R. Lawn, Herzl Chai

Research output: Contribution to journalArticlepeer-review


The role of elastic mismatch in determining critical conditions for indentation fracture in brittle coatings on substrates of unlike modulus was investigated. A model transparent trilayer system, consisting of a glass coating layer bonded to a thick substrate of different glass or polymer by a thin layer of epoxy adhesive, facilitated in situ observations of crack initiation and propagation. A tungsten carbide sphere was used to load the layer system. Abrasion flaws were introduced into the top and bottom glass coating surfaces to control the flaw populations and to predetermine the origins of fracture: cone cracks occurred at abraded top surfaces, radial cracks at abraded bottom surfaces. Analytical relations for the critical loads are presented for each crack system in terms of elastic modulus mismatch, indenter and coating dimensions, and material fracture parameters. Implications concerning materials selection for resistance to crack initiation are considered.

Original languageEnglish
Pages (from-to)1653-1656
Number of pages4
JournalJournal of Materials Research
Issue number8
StatePublished - Aug 2000


FundersFunder number
United States National Institute of Dental Research
National Institute of Standards and Technology
Korea Science and Engineering Foundation


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