Abstract

Corrosión behaviour of 75%Cr3C2-25%NiCr coatings deposited on 42CrMo6 steel by High Velocity Oxy-Fuel spraying (HVOF) was investigated. Three coatings were studied; two of them using different spraying parameters (standard and optimized) and third one submitted to a thermal treatment. The electrochemical behaviour of the coated steels was evaluated by means of Open Circuit Potential (Ecorr), Electrochemical Impedance Spectroscopy (E1S) and Polarization measurements (CP). The structural characterization has been performed by Optical and Scanning Electrón MiCroscopy (SF.M-EDS). before and after ¡inmersión in aerated H2SO4 0.5M solution. The standard sample showed a strong substrate influence during immersion due to the rapid electrolyte penetration through the coating, reaching the steel substrate. It was concluded that the thermal treatment performed during thermal spraying improved the coating behaviour against corrosión as the electrolyte did not reach the steel even after l month of immersion.