Title: High temperature corrosion behaviour of HVOF sprayed WC-CrC-Ni coatings

Authors: B. Somasundaram; Ravikiran Kadoli; M.R. Ramesh; C.S. Ramesh

Addresses: Department of Mechanical Engineering, Reva Institute of Technology and Management, Yelahanka, Bangalore – 560 064, India ' Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore – 575 025, India ' Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore – 575 025, India ' Department of Mechanical Engineering, PES Institute of Technology, Bangalore – 560 085, India

Abstract: The present work aims to study the hot corrosion resistance of high velocity oxy-fuel (HVOF) sprayed WC-CrC-Ni coating developed on three types of boiler tube materials such as SA213-T22, MDN-310 and Superfer 800 H steels. Hot corrosion studies were conducted in a molten salt environment of Na2SO4-60%V2O2 at 700°C and thermogravimetric analysis was used to establish kinetics of corrosion. Corrosion kinetics of coated steels followed nearly parabolic behaviour and showed a lower corrosion rate in comparison to uncoated alloys. It is concluded that corrosion is restricted to the external surface of the coating and the formation of thick scale composed of oxides of Cr, Ni and their spinel oxides, acts as a diffusion barrier to the transportation of corrosive species into the coating. The carbides of tungsten and chromium uphold the strength of the coating.

Keywords: high velocity oxy fuel; HVOF; high temperature corrosion; WC-CrC-Ni coatings; boilers; thermogravimetric analysis; corrosion kinetics; coated steel; parabolic behaviour; hot corrosion resistance; boiler tube materials; tungsten; nickel; chromium.

DOI: 10.1504/IJSURFSE.2016.077542

International Journal of Surface Science and Engineering, 2016 Vol.10 No.4, pp.400 - 413

Available online: 05 Jul 2016

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