Alkali Sulfate-Induced Hot Corrosion Resistance of Various Heat-Resistant Alloys

Alkali sulfate deposits are often present in the byproducts of combustion of many fossil-fuel fired systems such as in the advanced gas turbines and coal-fired power plants. Components used in these systems are apt to undergo accelerated degradation at elevated temperatures when exposed to such aggressive deposits. This study compares Type I hot corrosion resistance (i.e. 900^oC/ 1650^oF) of various Ni-, Co-, and Fe-based solid-solution strengthened alloys. The Type I hot corrosion conditions were simulated by depositing alkali sulfate salt on the test samples and then exposing those samples in a laboratory scale furnace rig to a catalyzed air: SOx atmosphere. Sodium sulfate (Na₂SO₄) salt was used to bring about the hot corrosion. Alloy performances were compared by assessing the weight-change behavior and metal recession as measured from the cross-sections.