Hot Corrosion of Co-based Alloys with 25%NaCl+75%Na_2SO_4 Coating at 1173 K

摘要

Hot corrosion behavior of pure Co, Co-10Cr and Co-10Cr-5Al alloys in the presence of a salt coat of Na_2SO_4+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 Cr_2O_3 and Al_2O_3, 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, Cr_2O_3, and small amount of Cr_2S_3. The corrosion resistance of Co-10Cr-5Al alloy is better than that of Co-10Cr alloy.