Corrosion of 304 stainless steel by molten NaNo3/KNO3 [sodium nitrate/potassium nitrate] in a thermal convection loop

by Livermore Sandia National Laboratories, CA

Other authorsRobert W. Bradshaw
Technical Report, 1980

Barcode

CSP Unique ID 190707579

Status

Electronic Resource

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**Click on MARC view for more information on this report.**

Publication

SAND Report: SAND80-8856, December 1980.

Language

Library's review

ABSTRACT:
The corrosion behavior of Type 304 stainless steel in molten NaN03-KN03 was studied at temperatures between 600°C and 350°C using thermal convection loops. Corrosion rates were somewhat less than 2.5 x 10-2 mm/year (1 mil/ year) at the maximum temperature. Two corrosion processes were
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observed, formation of oxide scales and depletion of chromium from the alloy. Oxidation products generally consisted of at least two layers, a layer of Fe304 over an iron-chromium spinel. In addition, a complex oxide was detected which appeared to be a double oxide of iron and, a salt impurity, magnesium. Chromium accumulated as a soluble product in the melt but thermal gradient mass transfer was not observed. Chromium depletion kinetics were approxi­mately parabolic with time suggesting a diffusion controlled process. Auto­genous weldments experienced somewhat more corrosion in the heat-affected zone than either the fusion zone or the parent alloy.
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