Deposit-induced Corrosion of Ni-base Alloys – Environmental and Alloying Effects

Corrosion of gas turbine components at high temperatures under salt deposits is a critical issue that can adversely affect their performance and longevity. The presence of calcium-containing compounds has been reported in these environments. These compounds may have different origins, e.g., sand particles, salts from marine atmospheres, atmospheric pollutants, etc. The consequences of the reactions between the salt deposits and the alloy substrate can result in enhanced solute depletion, and removal/ destruction of the external protective scale. In this presentation, the focus will be on the effect of chromium concentration, and process variables such as temperature, time and atmosphere, on the deposit-induced corrosion of Ni-base alloys. Degradation mechanisms will be discussed.