Study Of Refractory Coating For The Cord Steel Smelting

Cord steel is of high requirements on cleanliness of molten steel, and its refining conditions are harsh. Magnesia carbon brick of slag line is oxidized easily , and the ladle lining damage partially in the course of using, which cause a decrease of the survice life for ladle lining. Therefore, taking appropriate protective and maintenance measures to improve the survice life of ladle lining has great significance. This article used less aluminum materials to prepare anti-oxidation coating for magnesium carbon brick, discussed the effect of compositions on the surface morphology of coatings and the oxidation resistance, while the coating section microstructure and internal carbon element strength changes were analyzed. And the rheological characteristics of matrix composition of alkaline Jetting refractories for repairing were researched. Their influence mechanism were discussed, which can provide theoretical basis for improving the construction performance of spray refractories for cord steel smelting. The results showed that:(1) When the SiC content was 9wt%, the sample with coating spread well on magnesia carbon brick, and showed lower oxidative mass loss than samples without coating. The sample with 9wt% SiC, 30wt% fused silica and 4.94% Li₂CO₃ had the lowest oxidative mass loss, spread smoothly, and had good bonding with the magnesia carbon brick. From the coating surface to the inner of the coated sample, the intensity index of carbon element increased gradually. The carbon element of sample with 4.94% Li₂CO₃ had the minimum oxidation loss, and the oxidation resistance of the coating was the best.(2) The rheological type of the matrix slurry is Bingham model. The appropriate addition of water, SiO₂ power and magnesium powder is about 38%, 10% and 14%. Adding dispersants can improve the fluidity of the matrix slurry significantly. Compared with other accelerants, boric acid and Ca(OH)2 played the most significant role. Coagulant acid aluminum dihydrogen phosphate and so on can improve the viscosity of slurry significantly when additing more than 0.2%. EDTA·4H,EDTA·2H·2Na and EDTA·4Na had good chelation effect on the slurry, and the chelating capacity of EDTA·2H·2Na and EDTA·4Na are far lower than EDTA·4H.