Effect of film thickness on the fracture toughness of amorphous diamond-like carbon

Krishna Jonnalagadda, Ioannis Chasiotis

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

Abstract

Fracture toughness, KIC measurements were conducted for the first time on hydrogen-free tetrahedral amorphous Diamond-like Carbon (ta-C) MEMS-scale specimens of different thicknesses. Uniform gage microscale specimens with mathematically sharp edge pre-cracks were prepared by microindentation on the SiO2 sacrificial layer. The radial-median crack from the indent propagated into the specimen generating a sharp pre-crack. The crack length was measured by an Atomic Force Microscope (AFM). Freestanding fracture specimens were then obtained by wet etching the SiO2 sacrificial layer. Microtensile tests were performed on the precracked specimens under mode-I loading in fixed grip configuration. In order to investigate the specimen thickness dependence of KIC fracture tests were conducted on specimens with thicknesses in the range of 0.5-3 μm. KIC was 4.25 ± 0.7 MPa√m for 0.5 μm specimens, 4.4 ± 0.4 MPa√in for 1 μm specimens, and 3.06 ± 0.17 MPa√m for 3 μm thick specimens. The 25% lower fracture toughness of the 3 μm films points to a film thickness dependence of fracture toughness that was attributed to different through-the-thickness stresses in considerably thick ta-C films and compositional changes occurring during post-deposition processing.

Original languageEnglish (US)
Title of host publicationAmerican Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS
Pages363-364
Number of pages2
DOIs
StatePublished - Dec 1 2005
Event2005 ASME International Mecahnical Engineering Congress and Exposition, IMECE 2005 - Orlando, FL, United States
Duration: Nov 5 2005Nov 11 2005

Publication series

NameAmerican Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS
Volume7 MEMS
ISSN (Print)1096-665X

Other

Other2005 ASME International Mecahnical Engineering Congress and Exposition, IMECE 2005
CountryUnited States
CityOrlando, FL
Period11/5/0511/11/05

ASJC Scopus subject areas

  • Mechanical Engineering
  • Electrical and Electronic Engineering
  • Control and Systems Engineering

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  • Cite this

    Jonnalagadda, K., & Chasiotis, I. (2005). Effect of film thickness on the fracture toughness of amorphous diamond-like carbon. In American Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS (pp. 363-364). (American Society of Mechanical Engineers, Micro-Electro Mechanical Systems Division, (Publications) MEMS; Vol. 7 MEMS). https://doi.org/10.1115/IMECE2005-81631