MRS Bulletin

Technical Feature

Technical Feature

Nanocomposite Hard Coatings for Wear Protection

Jörg Patscheider

Abstract

Nanocomposite thin films successfully promote hardness, oxidation resistance, improved wear behavior, and other properties relevant for wear-reducing coatings. Such coatings are composed of nanocrystalline grains of transition-metal nitrides or carbides surrounded by an amorphous hard matrix. The properties of nanocomposite coatings, especially hardness, are directly linked to nanostructure. The codeposition of the amorphous and nanocrystalline phases of different compositions results in different morphologies, which in turn affect the coating's properties. A maximum hardness ranging from 30 GPa to reported values above 60 GPa has been observed for most nanocomposite coatings. To obtain enhanced hardness, the domain size of the nanocrystalline phase must be below 10 nm, while the thickness of the amorphous layer separating the nanocrystals must be maintained at only a few atomic bond lengths. The prime reason for the hardness enhancement is the absence of dislocation activity.

Keywords

  • nanocomposites;
  • elastic properties;
  • superhard coating materials;
  • thin films

Jörg Patscheider established the thin-film technology laboratory at EMPA (Swiss Federal Laboratories for Materials Testing and Research, Dübendorf) and has been a researcher there since 1991. He carries out application-oriented R&D work on thin films of diamond, diamond-like carbon, and nanocomposites with universities and industrial companies; at present, his interests lie in nanostructured coatings. Patscheider received his PhD degree from the University of Zurich for his work on plasma-assisted chemical vapor deposition of Al2O3 and TiN; following graduation, he was a postdoctoral fellow a Texas A&M University In 2002, he was a visiting scientist at the University of Illinois in Urbana-Champaign.

Patscheider can be reached by e-mail at joerg.patscheider@empa.ch.

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