Corrosion Mechanism of Slag-Line Materials in Blast Furnace Main Trough

摘要

The corrosion mechanisms of slag-line materials in a blast furnace main trough were investigated by finger corrosion tests between 1723 and 1823K with the oxygen partial pressure below 0.2 atm. The material was scarcely corroded by blast furnace slag in the part of the specimen submerged into the slag. However, local corrosion at the slag-atmosphere interface occurred in oxidizing atmosphere and the corrosion rate increased in proportion to p(O2). Moreover, the corrosion rate increased with the rotation speed of the test specimen. From the results, the rate-determining step of the local corrosion was found to be the diffusion of oxygen through the laminar slag film wetting the refractory. Therefore, the motion of the slag and Marangoni convection accelerate the corrosion. Both SiC and C in the material are oxidized by oxygen that diffuses through the laminar film. The formed SiO_2 reaction product then dissolves into the slag and CO escapes from the system.