High Purity Silicon Carbide

Industrial-grade silicon carbide is high-purity material with SiC content ≥90% and impurity levels of Fe, S, and P <1%. It typically exists as granular particles ranging from 1-5mm in size. In certain applications, silicon carbide is blended with small amounts of aluminum powder and calcium alloy to further enhance deoxidation efficiency and inclusion removal effectiveness.

Typically added 5-10 minutes before ladle tapping or after slag formation in the refining furnace. At this stage, the molten steel's elevated temperature accelerates silicon carbide dissolution and reaction. Premature addition may cause carbon to react with other elements in the molten steel, forming carbides that compromise the steel's mechanical properties.

Two methods exist for adding silicon carbide: bottom argon blowing + top wire feeding, and in-stream addition during tapping. The former method encapsulates silicon carbide particles within a steel ribbon, which is fed deep into the molten steel via a wire feeder. Combined with bottom argon agitation, this ensures thorough contact between silicon carbide and the molten steel. The latter method involves uniformly dispersing silicon carbide particles into the molten steel stream as it is transferred from the converter to the ladle. The impact force of the molten steel achieves initial mixing, followed by enhanced reaction through subsequent argon agitation.

After silicon carbide addition, real-time monitoring of molten steel oxygen content via an online oxygen analyzer is required, alongside observation of slag condition. A transition from black viscous slag to grayish-white loose slag, accompanied by a gradual decrease in CO gas evolution, indicates the deoxidation reaction is nearing completion.