Diamond nucleation from the gas phase onto cold-worked Co-cemented tungsten carbide

Riccardo Polini*, Pierangelo D'Antonio, Enrico Traversa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Co-cemented tungsten carbide (WC-Co) substrates with fine (1 μm) and coarse (6 μm) grain size were sintered using 6 wt.% Co as a binder. The as-sintered samples were ground to the final geometry (10 × 10 × 3 mm3). After the grinding treatment, the full width at half maximum (FWHM) of the WC X-ray diffraction (XRD) peaks indicated a high level of strain in a few micrometers thick surface layer, according to the penetration depth of Cu Kα radiation. The as-ground substrates were submitted to a two-step etching procedure with Murakami's solution, to roughen the surface, and 10 s acid wash to etch surface cobalt out. The Murakami's etching time was varied between 1 and 20 min. Fine- and coarse-grained substrates submitted to different chemical etching times were characterized by scanning electron microscopy and XRD, and then submitted to short diamond nucleation runs in a Hot Filament Chemical Vapour Deposition reactor. Both FWHM of WC peaks and diamond nucleation density decreased by increasing the Murakami's etching duration, providing that the etched layer did not exceed 2 μm thickness. When a layer thicker than a couple of micrometers was removed by etching, diamond nucleation density was very low and no more dependent on etching time. This occurrence suggested that diamond nucleation density correlates well with the amount of residual strain at the substrate surface and can be tailored by a suitable control of strain-related defects produced by mechanical treatments.

Original languageEnglish (US)
Pages (from-to)340-345
Number of pages6
JournalDiamond and Related Materials
Volume12
Issue number3-7
DOIs
StatePublished - Jan 1 2003

Keywords

  • Cemented carbide
  • Cutting tools
  • Nucleation and growth
  • Surface pre-treatment

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Chemistry(all)
  • Mechanical Engineering
  • Physics and Astronomy(all)
  • Materials Chemistry
  • Electrical and Electronic Engineering

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