Surface modification of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

W. M. Silva*, V. J. Trava-Airoldi, Y. W. Chung

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Because of the high residual compressive stress normally accompanying the growth of diamond-like carbon (DLC) coatings and the large mismatch in the thermal expansion coefficient between DLC and steel, it is difficult to grow DLC coatings much thicker than 0.25 μm on steels. This paper describes our attempt to overcome this thickness limitation by a sequence of carbonitriding, carburizing and equilibration pre-treatments of the steel surface, followed by DLC coating deposition, all conducted within the same deposition system without breaking vacuum. These pre-treatments resulted in a surface with a graded composition and hardness profile. Such a graded interface is expected to reduce the interfacial energy, decrease thermal mismatch between the coating and the substrate, and thus improve coating adhesion. X-ray diffraction revealed the formation of various hard carbide and nitride phases. Raman spectroscopy showed that the modified steel surface just before DLC deposition exhibits local carbon bonding characteristics similar to DLC. Pulsed dc plasma-enhanced chemical vapor deposition was used to deposit one-micron thick DLC on these steel surfaces. The coating hardness was ~. 18-19. GPa. Its adhesion on the steel substrate was measured by scratch testing and was found to be comparable to thick, adherent DLC coatings deposited by other methods.

Original languageEnglish (US)
Pages (from-to)3703-3707
Number of pages5
JournalSurface and Coatings Technology
Volume205
Issue number12
DOIs
StatePublished - Mar 15 2011

Keywords

  • Adhesion
  • Carbonitriding
  • Diamond-like Carbon
  • Diffusion
  • Hardness
  • Scratch Testing

ASJC Scopus subject areas

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

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