Relationships between hardness, Young's modulus and elastic recovery in hard nanocomposite coatings

J. Musil, F. Kunc, H. Zeman, H. Poláková

Research output: Contribution to journalArticle

372 Citations (Scopus)

Abstract

The paper is devoted to an assessment of the mechanical behavior of hard and superhard nanocomposite coatings from loading/ unloading curves measured by a computer-controlled Fischerscope H 100 microhardness tester and a maximum depth dmax of the diamond indenter impression into the coating at a given load L. It is shown that: (1) the area between the loading/unloading curve and the value of dmax decreases with increasing (i) hardness H, (ii) effective Young's modulus E =E/(1-v2) and (iii) universal hardness HU, where E and v are the Young's modulus and the Poisson ratio, respectively; and (2) there is no simple relation between the mechanical response of the coating and H or E alone; however, this response is strongly dependent on the ratio H/E. The last fact gives a possibility of tailoring the mechanical properties of a coating for a given application, e.g. to prepare coatings with high hardness H, high resistance to plastic deformation (ΟH3 /E2), high elastic recovery Wc, but with low E and high dmax. Special attention is also given to the analysis of problems in accurately measuring the hardness of superhard (≥60 GPa) coatings. It is shown that a high elastic recovery Wc≥80% of superhard films with H≥60 GPa (1) strongly decreases the gradient dH/dL and (2) shifts the region L, where H(L) ≈ constant and the hardness H is correctly measured, to higher values of L. This means that the lowest load L used in the hardness measurement must be higher than L used in measurements of coatings with H<60 GPa to prevent the value of H measured from being significantly higher than the real hardness of the coating.

Original languageEnglish
Pages (from-to)304-313
Number of pages10
JournalSurface and Coatings Technology
Volume154
Issue number2-3
DOIs
Publication statusPublished - 15 May 2002

Fingerprint

modulus of elasticity
Nanocomposites
nanocomposites
hardness
Elastic moduli
Hardness
recovery
coatings
Recovery
Coatings
unloading
Unloading
Diamond
high resistance
Poisson ratio
curves
test equipment
Microhardness
microhardness
plastic deformation

Keywords

  • Magnetron sputtering
  • Mechanical properties
  • Microindentation measurements
  • Nanocomposite films

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Relationships between hardness, Young's modulus and elastic recovery in hard nanocomposite coatings. / Musil, J.; Kunc, F.; Zeman, H.; Poláková, H.

In: Surface and Coatings Technology, Vol. 154, No. 2-3, 15.05.2002, p. 304-313.

Research output: Contribution to journalArticle

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