Hot Corrosion of Co-based Alloys with 25%NaCl+75%Na2SO4 Coating at 1173 K

Abstract

Hot corrosion behavior of pure Co, Co-10Cr and Co-10Cr-5Al alloys in the presence of a salt coat of Na2SO4+NaCl in air at 1173 K was studied. The results indicated that among the three samples, the mass gain of Co-10Cr-5Al alloy is the smallest, while that of Co-10Cr is biggest. The corrosion products of Co-10Cr-5Al can be divided into three layers, of which the outside layer is CoO, the middle layer consists of Cr2O3 and Al2O3, and the inside layer is a small amount of Chromium sulfide and aluminum sulfide. The corrosion products of Co-10Cr can also be divided into three layers, from the outermost to the innermost layer are CoO, Cr2O3, and small amount of Cr2S3. The corrosion resistance of Co-10Cr-5Al alloy is better than that of Co-10Cr alloy.

Keywords

• co-based alloys
• na2so4+25%nacl salt film
• hot corrosion