Influence of KCl and HCl on a Laser Clad FeCrAl Alloy: In-Situ SEM and Controlled Environment High Temperature Corrosion

TL;DR

This study examines how HCl and KCl affect the corrosion behavior of laser clad FeCrAl alloy coatings at high temperatures, revealing interactions with chlorine and their impact on corrosion mechanisms.

Contribution

It provides new insights into the combined effects of HCl and KCl on FeCrAl alloy corrosion under simulated biomass boiler conditions.

Findings

HCl facilitates chlorine-based corrosion from the gas phase.

Presence of HCl and KCl reduces mass gain compared to KCl alone.

Slow growth of aluminium oxide observed during exposure.

Abstract

Increasing pressure on the power industry to reduce carbon emissions has led to increased research into the use of biomass feedstocks. This work investigates the effects of HCl and KCl, key species influencing biomass boiler corrosion, on a laser clad coating of the FeCrAl alloy Kanthal APMT. In-Situ SEM exposure of the coating at 450 oC for 1 h was performed to investigate the initial effects of KCl on the corrosion process. The same coatings were exposed to 250 h exposures in both an air environment and a HCl rich environment. The influence of KCl was investigated in both. Evidence of a slow growing aluminium oxide was observed. It was found that HCl allowed chlorine based corrosion to occur suggesting it can interact from the gas phase. It was also observed that the presence of both HCl and KCl reduced the mass gain compared to KCl in an air environment.