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_(2)SO_(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_(2)O_(3)and Al_(2)O_(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_(2)O_(3), and small amount of Cr_(2)S_(3). The corrosion resistance of Co-10Cr-5Al alloy is better than that of Co-10Cr alloy.