Is KCl(g) corrosive at temperatures above its dew point? - Influence of KCl(g) on initial stages of the high temperature corrosion of 11% Cr steel at 600 degrees C
Artikel i vetenskaplig tidskrift, 2004

The influence of gaseous KCl on the high temperature oxidation of CrMoV11 1 (X20) steel at 600degreesC is reported. The sample temperature was above the dew point of KCl, the partial pressure of KCl being about 5ppm. The samples were investigated by a number of surface analytical techniques including grazing angle XRD, SEM/EDX, and SAM. CrMoV11 1 steel shows protective behaviour in clean dry O-2 and O-2/H2O environment because of the formation of a chromium-rich oxide (alpha-(Fe,Cr)(2)O-3). It is Often considered that alkali salts accelerate the corrosion of steel only when present on the surface in solid or liquid form. In contrast, the present result shows that gaseous KCl is very corrosive, also in the absence of condensation. KCl(g) reacts with chromium in the scale, forming K2CrO4(s). This depletes the protective oxide in chromium and leads to the formation of non-protective hematite, Fe2O3.

water-vapor

11%Cr steel

temperature corrosion

chloride

deposits

fe-cr

chromia-forming steels

KCl(g)

alkali-induced high

oxidation

alloys

Författare

Karin Segerdahl

Chalmers, Institutionen för oorganisk miljökemi

Jesper Liske

Chalmers, Institutionen för oorganisk miljökemi

Jan-Erik Svensson

Chalmers, Institutionen för oorganisk miljökemi

Lars-Gunnar Johansson

Chalmers, Institutionen för oorganisk miljökemi

High Temperature Corrosion and Protection of Materials 6, Prt 1 and 2, Proceedings

Vol. 461-464 109-116

Ämneskategorier

Materialteknik

Kemi