High Temperature Corrosion of Inconel 600 in NaCl-KCl Molten Salts

G Salinas-Solano,L Martinez-Gomez,J Porcayo-Calderon,J A Ascencio-Gutierrez,V M Salinas-Bravo,J G Gonzalez-Rodriguez

doi:10.1155/2014/696081

Abstract

In this work the corrosion resistance of a high content nickel alloy, Inconel 600, was investigated in mixed NaCl-KCl salts at 700, 800, and 900°C for 100 hours in static air. Investigation was carried out using electrochemical techniques such as polarization curves, rest potential measurements, linear polarization resistance, and electrochemical impedance spectroscopy. Corroded specimens were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Electrochemical measurements showed an increased degradation rate of Inconel 600 with increasing test temperature. SEM and EDS analysis show that the damage experienced by Inconel 600 is greater than that determined by electrochemical measurements. This damage was identified as internal corrosion due to the reaction of Cl2with the alloying elements (Cr and Fe); however, at 900°C the internal damage was minor and it was associated with the nickel content in the alloy.

Highlights

Problems with process equipment resulting from fireside corrosion have been frequently encountered in waste incinerators and biomass-fired boilers
The corrosion resistance of Inconel 600 in NaCl-KCl at 700∘C, 800∘C, and 900∘C was studied by electrochemical techniques an scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis
Corrosive attack was documented by SEM and EDX analysis

Summary

Introduction

Problems with process equipment resulting from fireside corrosion have been frequently encountered in waste incinerators and biomass-fired boilers. The major problem is the complex nature of the feed (waste) as well as corrosive impurities which form low-melting point compounds with heavy and alkali metal chlorides which prevent the formation of protective oxide scales and cause an accelerated degradation of metallic elements [1]. Heat-resistant alloys survive high temperature exposure by growing protective oxide scales. This process involves the selective oxidation of an alloy constituent and necessarily leads to a change in alloy compositions in the subsurface regions. On the other hand it has been suggested that the NiCr-based alloys show better performance than Fe-base alloys This combined effect has been established in other studies [9,10,11,12,13,14]. This work addresses the corrosion resistance of Inconel 600 in NaClKCl mixture (1 : 1 M) at 700, 800, and 900∘C for 100 hours in static air

Experimental

Results and Discussion

Conclusions