Effect of pre-oxidation on the hot corrosion of CoNiCrAlYRe alloy

The effect of pre-oxidation on the resistance to hot corrosion was examined by corroding the CoNiCrAlYRe alloy at 900 degrees C in molten Na2SO4 Preoxidized specimens featured strong adhesion of oxide scale with uniform multi-layered structure The time of pre-oxidation was crucial for controlling Al content sufficient for subsequent hot corrosion However direct corrosion yielded a defective and non-protective oxide scale which allowed detrimental penetration of sulfur into substrate Sulfur migrating along phase boundary was trapped by yttrium to diminish slightly sulphidation Thus two advantages of proper pre-oxidation treatment were presented as keeping repairing for Al2O3 scale and inhibiting sulfur penetration (C) 2010 Elsevier Ltd All rights reserved