High temperature corrosion studies. A. Iron: based superalloy in SO/sub 2//O/sub 2/ atmospheres. B. Gas: solid reaction with formation of volatile species

Abstract

unknown ~easons (164). Fifth, the formation of volatile species plays an ~mFortant role in many high temperature gas-sol~4 metallurgical reactions. !his type ~f reaction should be ~pn~idered ~ith the scale formation reaction in order to evaluate the high temperature material performance. The oxida~ive volatilization of chromium oxide• at very high temperatures can pecome significant since the latter material is one 9t ~~e ~o~t important protective scales in many high temperatu~e ~~l9ys. The p~es~n~ ipvestigation is divided into two c~tegori~s which are b~sl~~llY related to each other in the study of gaseous ~9~~9sipn of metals at high• temperatures.. The first is the experlmeutal study of the corrosion behavior of several i~9n~~ased superalloys and pure chromium metals under so 2 ,o 2 atmosph~~es between 750 ~nd 1100°C by the thermogr~vimet~ic method. Different kinetic models were employed ~o ~n,ly~e the data in oE~er to get the most reliable re~ction rate constants. The effects of sulfur activity ~~9 g~? !low on the corrosion rate were studied. The activation energies were obtained from fitting the reaction rate to the Arrehenius equation. The reaction products were examined by met~_llographic procedufe•~• X-ray .. diffractipp method and electron microprobe analysis. The second part of this investigation reevaluated the published kinetic data of several gas-solid reactions ~ith the ~