Hot-Corrosion Resistance of Ni–Cr–Al–Y and Ni–18% Si Alloys in Sulfate Eutectic and Sulfate Plus Vanadate Melts at 973 K

The hot-corrosion resistance of Ni–Cr–Al–Y and Ni–17.8 wt.% Si was examined in sulfate and sulfate plus vanadate melts at 973 K. Two salt-deposit compositions were considered: (a) sodium sulfate+50 mole% magnesium-sulfate eutectic and (b) sodium sulfate plus 20 mole% sodium meta-vanadate. Both types of deposit were molten at the test temperature. Cyclic hot-corrosion tests were conducted in a gas mixture consisting of oxygen, sulfur dioxide, and 0.0240 vol.% sulfur trioxide. The hot-corrosion kinetics were evaluated using weight change and the corrosion mechanism deduced from post-test metallography. The results indicate that the nickel–silicon alloy had much better hot corrosion resistance than Ni–Cr–Al–Y under all test conditions considered. The sample preparation process is outlined, the test procedure summarized, and the experimental results are presented and discussed.