Influence of Feedstock and Thermal Spray Process on the Phase Composition of Alumina Coatings and Their Sliding Wear

Omar Ali, Rehan Ahmed*, Filofteia Laura Toma, Lutz-Michael Berger, Björn Matthey, Nadimul Faisal, Khalid Ahmed

*Corresponding author for this work

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Abstract

Suspension thermal spraying is an emerging coating technology that enables the deposition of dense-structured ceramic coatings. As wear resistance is a main application field of alumina (Al2O3) coatings, this study aimed to evaluate the dry reciprocating sliding wear resistance of suspension sprayed high velocity oxy-fuel (S-HVOF) alumina coatings and to compare it with atmospheric plasma sprayed (APS) and HVOF coatings. Coatings were analyzed in the as-sprayed state and post-treated at 910 °C (hot isostatically pressed, HIPed) conditions. Wear tests were conducted using a tribometer, following the ASTM G133-02 standard and a sintered WC-6 wt.% Co ball as the counterbody. Coating characterization was done using scanning electron microscopy, x-ray diffraction and nanoindentation technique. Results indicate that the HVOF, HVOF-HIP and S-HVOF coatings had a high α-Al2O3 content, whereas the APS and APS-HIP coatings had a high γ-phase content together with high porosity. Sliding wear resistance was an order of magnitude higher for the S-HVOF and HVOF coatings than the APS and APS-HIPed coatings. This difference in wear performance was attributed to the high nanohardness, elastic modulus, dense microstructure and relatively high α-Al2O3 content in the HVOF, S-HVOF and HVOF-HIP coatings. Results are discussed in terms of the wear mechanism and structure-property relationship.

Original languageEnglish
Pages (from-to)2028-2053
Number of pages26
JournalJournal of Thermal Spray Technology
Volume32
Issue number7
Early online date19 Jun 2023
DOIs
Publication statusPublished - Oct 2023

Keywords

  • alumina coating
  • sliding wear
  • structure-property relationship
  • suspension
  • thermal spray coating
  • wear mechanism

ASJC Scopus subject areas

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

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