Reversing the inverse hardness-toughness trend using W/VC multilayer coatings

Kaicheng Shi, Chen Wang, Cameron Gross, Yip Wah Chung*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


It is desirable to increase the hardness of protective coatings for reduced abrasive wear and to increase the toughness for improved wear performance due to fatigue and formation of flaws or cracks. Unfortunately, there is an inverse relationship between hardness and toughness: the harder the coating, the lower the toughness. Using W/VC multilayer coatings, we demonstrated that it is possible to reverse this hardness-toughness trend. These coatings were synthesized by DC magnetron sputtering with bilayer periods of about 10nm and different thickness fractions of W. They are crystalline, with hardness and toughness exceeding that of pure VC (25GPa and 1.0MPa-m1/2). In particular, the W/VC multilayer coating with thickness fraction of 90% W achieves hardness of 28.5GPa, comparable to many ceramics-based hard coatings, and toughness of 7.5MPa-m1/2, similar to many nanocrystalline metals. This investigation shows that one can synthesize coatings as hard as ceramics and as tough as metals. These results also indicate that H/E and H3/E2 (H=hardness and E=elastic modulus) are not good proxies for coating toughness.

Original languageEnglish (US)
Pages (from-to)80-84
Number of pages5
JournalSurface and Coatings Technology
StatePublished - Dec 25 2015


  • Hardness
  • Multilayer coatings
  • Toughness

ASJC Scopus subject areas

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


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