High Temperature Corrosion of CoNiCrAlY-Si Alloys in an Air-Na₂SO₄-NaCl Gas Atmosphere

Abstract

The addition of Si to CoNiCrAlY was considered in order to develop corrosion resistant alloys for coating applications. The high temperature corrosion behavior of spark plasma sintered CoNiCrAlY alloys of 0, 10, 20, and 30 mass% Si content was investigated in an air-(Na₂SO₄+25.7 mass%NaCl) gas atmosphere at elevated temperatures of 923, 1073, and 1273 K. The results showed that CoNiCrAlY-Si alloys formed mainly an Al₂O₃ or Al₂O₃/SiO₂ scale, depending on the alloy composition and the temperature. The addition of 30 mass% Si significantly improved the high-temperature corrosion resistance of CoNiCrAlY alloy in an air-(Na₂SO₄+25.7 mass%NaCl) gas atmosphere at these temperatures. The high temperature corrosion behavior of CoNiCrAlY-Si alloys was discussed in the present paper.