High temperature corrosion and electrochemical behavior of HVOF sprayed Inconel 718 coating using an innovative device: HTCMD

Abstract

Inconel 718 is one of the most commonly used nickel‐based superalloy materials in petroleum industry due to its high temperature mechanical properties and corrosion resistance. Generally, corrosion resistance assessment of materials at high temperature condition is a challenging task and most of the previous studies in this area were based on estimation of weight‐loss in the sample, which cannot provide accurate results, and it could be very time‐consuming. In this study, a high temperature corrosion measurement device (HTCMD) was used to evaluate electrochemical behavior of HVOF deposited Inconel 718 coating in 3.5 wt% NaCl solution at elevated temperatures. EIS and potentiodynamic polarization results revealed very low corrosion rate of the Inconel 718 coating. Materials characterization by SEM, XRD, and EDS indicated formation of chromium oxide rich unstable passive layer resulted in localized protection of superalloy material that was not sufficient to provide corrosion protection for the entire surface, during the service at high temperature condition.

Effect of heat treatment on the δ phase distribution and corrosion resistance of selective laser melting manufactured Inconel 718 superalloy

“…The excellent corrosion resistance of Inconel 718 could be attributed to the formation of Cr 2 O 3 thin layer on the surface, but the passive layer was not stable and will be destroyed with the time increased in chloride ions solution. In Figure , the FeCl 3 immersion test shows that during the same immersion time, HT950 treated sample showing much weak corrosion attack on the surface, which indicated that HT950 treated sample have lower corrosion rate.…”