Microstructure and tribological properties of plasma-sprayed chromium oxide - molybdenum oxide compostie coatings

In Woong Lyo, Hyo Sok Ahn, Dae Soon Lim

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)


Plasma-sprayed composite coatings of Cr2O3-MoO3 were studied to identify their microstructure and to understand the influence of molybdenum oxide composition in the coatings on their tribological behavior. Cr2O3-MoO3 composite powders and Cr2O3 powders were fabricated using a spray-drying method and plasma-sprayed coatings of these powders were produced to evaluate their tribological performance. Wear tests were conducted with a reciprocating motion at room temperature and 450 °C under dry sliding condition. Measurement of friction coefficient was made in association with the sliding cycle. The physical characteristics of surfaces were investigated by scanning electron microscopy and chemical composition of the coating surfaces was analyzed using a X-ray photoelectron spectrometer and a transmission electron microscope (TEM). The study showed that the microhardness of coatings containing MoO3 were higher than that composed of Cr2O3 alone. The result of TEM analysis indicated that chromium/molybdenum was precipitated in the grain and grain boundary. The friction coefficients of the MoO3 -added coatings were lower than that without MoO3 addition at both test temperatures. However, the addition of MoO3 in the Cr2O3 coatings did not significantly improve the wear performance of the coatings at both test temperatures. Dispersed smooth films were formed in the worn surface for all coatings. These wear protecting layers, formed by plastic deformation of adhered and compacted debris particles to the surface, strongly influence the friction of the coatings as already observed by the authors with different plasmasprayed coatings. The chemical composition of these films varied depending on the test temperature.

Original languageEnglish
Pages (from-to)413-421
Number of pages9
JournalSurface and Coatings Technology
Publication statusPublished - 2003 Jan 30

Bibliographical note

Funding Information:
The authors would like to thank the Ministry of Science and Technology and the Critical Technology 21 Program (Machinery Design Technology Enhancement) for financial support and interest in this work.

Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.


  • Friction and wear
  • Plasma-sprayed CrO-MoO composite coatings
  • Surface films
  • Transmission electron microscopy
  • X-ray photo electron spectroscopy

ASJC Scopus subject areas

  • General Chemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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