Corrosion of in situ TiN/O'-sialon materials by blast furnace cohesive zone slag

Corrosion mechanism of in-situ TiN/O'-sialon composites exposed to simulated blast furnace (BF) cohesive zone slag was investigated by means of static droplet method. High-temperature X-ray fluoroscopy was used to monitor the melting of slag and the interaction process between slag and the materials. Phase composition of residue slag was analyzed by XRD. The microstructure, element distribution and corrosion depth of the corroded region of the materials were observed and determined by EPM. The results show that the main corrosion mechanism of TiN/O'-sialon is the penetration of molten slag and the chemical reaction between the material and molten slag. After being corroded, the structure of TiN/O'-sialon material changes to form slag zone, penetrated zone and unchanged zone. During corrosion process, some newly formed high-melting-point phases by the interaction between molten slag and the material and TiN in the material cause the increase of viscosity of the molten slag and the decrease of fluidity, which will prevent the further corrosion. Therefore the corrosion resistance to slag of the materials can be improved by the increase of TiN content.