A comparison between the corrosion resistances of High Velocity Oxy Fuel (HVOF) sprayed coatings and hard chromium coatings

Saghi Beyragh, M. R ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.4028/www.scientific.net/MSF.673.173
  3. Publisher: 2011
  4. Abstract:
  5. HVOF-sprayed coatings (WC-17%Co) and hard chromium coatings corrosion resistances have been compared through electrochemical polarization test in 3.5% NaCl solution. WC-17%Co alloy coatings were deposited on mild steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. The layers of standard and crack free hard chromium coatings were prepared by using Direct Current (DC) and Pulse Current (PC) electroplating process on the mild steel substrates. Hard chromium coatings was characterized as a reference material, to verify whether HVOF-sprayed coatings are suitable as a hard chromium coatings replacement. The microstructure of the coatings was examined by OM, SEM and XRD. Standard hard chromium coatings passivate in NaCl environment, but crack free hard chromium coatings were prepared by using Pulse Current (PC) electroplating do not passivate. The lowest corrosion current densities (Icorr) were recorded for crack free hard chromium coatings. Comparative electrochemical test results showed that, the Standard hard chromium coating has the highest I corr and were significantly damaged after the electrochemical tests. It is seem to be that WC-17%Co alloy coatings can be substituted for standard hard chromium coatings but crack free chromium coatings bring new challenge for HVOF-sprayed coatings!
  6. Keywords:
  7. Corrosion polarization test ; Crack free coatings ; Hard chromium ; HVOF coatings ; Polarization tests ; Pulse electroplating process ; Carbon steel ; Chromium ; Cobalt alloys ; Corrosion resistance ; Cracks ; Electroplating ; Fuels ; Hard coatings ; High energy physics ; HVOF thermal spraying ; Metal coatings ; Polarization ; Shock waves ; Sodium chloride ; Standards ; Tungsten carbide ; Sprayed coatings
  8. Source: Materials Science Forum, 1 September 2010 through 3 September 2010, Seoul ; Volume 673 , 2011 , Pages 173-178 ; 02555476 (ISSN) ; 9783037850183 (ISBN)
  9. URL: http://www.scientific.net/MSF.673.173