Fracture toughness of tetrahedral amorphous diamond-like carbon specimens of various thicknesses

Krishna Jonnalagadda, Sung Woo Cho, Ioannis Chasiotis

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We present fracture toughness measurements conducted on Hydrogen-free tetrahedral amorphous Diamond-like Carbon (ta-C) MEMS-scale specimens with thickness in the range of 0.5 - 3μm. Edge pre-cracks were generated in uniform gage specimens via microindentation of the supporting SiO 2 sacrificial layer. One of the indentation cracks propagated in the SiO 2 layer and into the ta-C specimen generating a mathematically sharp crack. The precise crack length was determined using an Atomic Force Microscope (AFM). The pre-cracked specimens were released from the sacrificial SiO 2 via wet etch and mode-I micro-tensile tests were performed on the freestanding specimens. Since ta-C is perfectly brittle the mode-I fracture toughness K IC was computed using the linear elastic fracture mechanics solution (LEFM). K IC was found to be 4.25 ± 0.7 MPa√m for 0.5 μm specimens, 4.4 ± 0.4 MPa√m for 1 μm specimens, and 3.06 ± 0.17 MPa√m for 3 μm specimens. Unlike macroscale specimens, this thickness dependence of fracture toughness is not attributed to a plane stress state. Rather, the observed trends may have arisen from through-the-thickness compositional variations and residual stresses.

Original languageEnglish (US)
Title of host publicationProceedings of the 2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics
Pages1109-1114
Number of pages6
StatePublished - Dec 1 2005
Event2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics - Portland, OR, United States
Duration: Jun 7 2005Jun 9 2005

Publication series

NameProceedings of the 2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics

Other

Other2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics
CountryUnited States
CityPortland, OR
Period6/7/056/9/05

Keywords

  • Fracture toughness
  • MEMS
  • Mechanical properties
  • Ta-C
  • Thin films

ASJC Scopus subject areas

  • Engineering(all)

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  • Cite this

    Jonnalagadda, K., Cho, S. W., & Chasiotis, I. (2005). Fracture toughness of tetrahedral amorphous diamond-like carbon specimens of various thicknesses. In Proceedings of the 2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics (pp. 1109-1114). (Proceedings of the 2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics).