Effect of Phosphate Antioxidant on Resisting to Buildups Formation of Carbon Sleeves in Continuous Annealing Furnace for Silicon Steel Production

Phosphate is an antioxidant commonly used for impregnating treatment of low-temperature and medium-temperature carbon sleeves for continuous annealing furnace in silicon steel production. The microstructure, topography and composition of the buildups embedded on and adhered to the surface of the carbon sleeve were investigated by SEM and EDX. The water resistance performance of carbon sleeve dipping with phosphate was tested by soaking method. It is found that the buildups contain high phosphorus which mainly comes from phosphate antioxidants in the carbon sleeve. A large quantity of white substances seeped out to the surface of carbon sleeve after soaking for 24 h. The water resistance of carbon sleeve treated with phosphate antioxidant was poor. In terms of the resistance to buildups formation and water, phosphate is not a good antioxidant for carbon sleeve in continuous annealing furnace for silicon steel production.