Abstract
Abstract
Metallic high-velocity oxy fuel (HVOF) coatings are increasingly being used to provide corrosion protection in process engineering environments. In this paper the microstructural and corrosion characteristics of HVOF-sprayed Inconel 625 are considered and compared with wrought Inconel 625. Electrochemical techniques (a.c. and d.c.) have been used to characterize the corrosion behaviour of the coating and wrought alloy in static saline conditions at ambient temperature (18°C) and at a higher temperature (50 °C). Galvanic corrosion tests between Inconel 625 and carbon steel have been conducted. Using a combined electrochemical monitoring and microstructural examination methodology, it has been shown that HVOF-sprayed Inconel 625 suffers localized corrosion not evident on the wrought alloy. In addition it has been demonstrated that no benefits in corrosion performance are gained by using a vacuum impregnation technique to seal the surface of the coating.
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