Na_2SO_4-NaCl 混合塩塗布試験におけるニッケル基単結晶超合金の高温腐食におよぼす Cr および Re の効果

概要

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The alloying effect of chromium and rhenium was investigated on the hot-corrosion resistance of nickelbased single crystal superalloys. Using a conventional thermo-gravimetric method, hot-corrosion resistance to the Na_2SO_4-NaCl salt environment was measured with a variety of alloys, Ni-(9∿16)mol% Cr-12mol% Al-(1.2∿2.0)mol% Ti-(1.1∿2.7)mol% Ta-(1.2∿3.8)mol% W-(0∿1.0)mol% Mo-(0∿1.0)mol% Re. Hot-corrosion resistance was shown to be improved significantly with increasing chromium content in the alloys. For example, a hot-corrosion index which was defined as the weight gain of the specimen exposed for 72ks to the salt, was reduced to nearly nil in the 16mol%Cr alloys. This result was interpreted as due to the existence of a corrosion product layer containing Cr, Al, Ni, O and S. This layer formed in the interface between the base alloy and the salt was very efficient in suppressing the hot-corrosion due to a basic-fluxing mechanism. Similarly, it was found that the addition of a small amount of rhenium up to 0.4∿0.5mol% could improve hot-corrosion resistance remarkably.
社団法人日本鉄鋼協会の論文
1992-05-01