Oxidation resistance and self hardening of CrAlN/BN nanocomposite coatings

Masateru Nose*, Tomohiro Watanuki, Tokimasa Kawabata, Yuji Hatano, Kenji Matsuda, Ssusumu Ikeno

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

CrAlN/BN nanocomposite coatings were deposited on mirror-polished silicon wafer and high-speed steel (HSS) substrates using reactive cosputtering, i.e., pulsed dc and rf sputtering of CrAl and h-BN targets, respectively. Further, the oxidation resistance of the obtained coatings was investigated. The CrAlN/BN coating exhibited superior oxidation resistance properties when compared with those of the CrAlN coatings; after annealing the sample at 800 °C in air for 1 h, the plastic hardness value of the CrAlN coatings decreased to 50% of the as-deposited hardness value; in contrast, the CrAlN/BN coatings exhibited self hardening phenomena from 700 to 800 °C in the range of 5 to 30%. In particular, the CrAlN/18 vol% BN coatings showed an increase of approximately 30% in hardness values, and a maximum hardness value of approximately 50 GPa was reached after annealing the sample at 800 °C in air. The plastic hardness value hardly changed when the sample was annealed up to 800 °C in nitrogen and argon; this result was contrary to the result obtained for the sample that was annealed in air. The radiofrequency glow discharge optical emission spectroscopy (rf-GD-OES) analysis of the CrAlN/18 vol% BN coating annealed in air revealed that the coating has an oxide layer deposited on the surface to a depth of ∼200 nm. Conventional transmission electron microscopy (TEM) observations of the same coating indicate that the columnar structure was disrupted by a thin layer (30-40 nm) of the coating annealed in air. The indentation hardness value of the annealed coating was measured using Ar ion sputtering before and after etching of the annealed surface. Subsequently, when the oxide layer was etched to a depth of 200 nm from the surface, the hardness value decreased from approximately 48 GPa to 43 GPa; this result was similar to the results obtained for the as-deposited coating.

Original languageEnglish
Title of host publicationTHERMEC 2011
PublisherTrans Tech Publications Ltd
Pages2559-2564
Number of pages6
ISBN (Print)9783037853030
DOIs
StatePublished - 2012
Event7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011 - Quebec City, QC, Canada
Duration: 2011/08/012011/08/05

Publication series

NameMaterials Science Forum
Volume706-709
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

Conference

Conference7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011
Country/TerritoryCanada
CityQuebec City, QC
Period2011/08/012011/08/05

Keywords

  • CrAlN/BN
  • Hard coating
  • Nanocomposite
  • Oxidation resistance
  • Self hardening

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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