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Ferrosilicon inoculant, also known as ferrosilicon particles, is a granular material made of ferrosilicon alloys through crushing and sieving. The core component is silicon (usually 65%-80%), and the particle size is mostly controlled at 0.2-10mm. Its production requires three steps: first, silica (SiO₂) and coke are used as raw materials, and reduced and smelted in an electric furnace of 1600-1800℃ to form coarse silicon with a purity of 95%-98%; then it is removed by crushing, pickling and sieving to make industrial silicon; finally, the ferrosilicon alloy (such as FeSi75) is accurately crushed, and the fine powder is removed through the screen to form silicon particles with uniform particle size.
In cast iron production, silicon particles are used as an efficient incubator to optimize casting performance through the dual mechanism of 'graphitization regulation + heterogeneous nucleation':
Inhibit white mouth and improve processability: The silicon elements decomposed by silicon particles promote the decomposition of iron carbide into graphite, reducing the thickness of the casting white mouth layer.
Refine graphite and grains: The aluminum and calcium in the silicon particles form high-melting point particles (such as Al₂O₃), providing a heterogeneous nucleation core for graphite.
Equilibrium tissue and reduce defects: Silicon particles with uniform particle size (such as 0.5-2mm) can reduce wall thickness sensitivity and eliminate microshrinkage.
Balance between advantages and limitations
Significant advantages:
Process stability: Fine-free design avoids burning, the absorption rate is stable between 70%-90%, which is 20% higher than ordinary ferrosilicon fertilization effect, and the slag volume is reduced by 40%.
Long-term anti-decay: The anti-decay time of silicon strontium composite particles is twice that of ordinary ferrosilicon, which is suitable for continuous production of assembly lines, and solves the problem of spheroidization decay within 15 minutes.
Cost optimization: The dosage is only 1/2 of 75 ferrosilicon, and the mold life is extended by 10%-15%, and the overall cost is reduced by 8%-12%.
Potential risks:
Excessive silicon brittleness: Adding more than 0.8% can easily cause ferrite to roughen, and a company will accidentally increase to 1.2%, and the casting hardness dropped from HB200 to HB160, and its toughness decreased by 25%.
Particle size sensitivity: The oxidation loss of overly fine particles (<0.1mm) is high, and the absorption rate decreases by 40%; the dissolution is slow, and the risk of local silicon segregation increases.
Component constraints: The silicon content needs to be strictly controlled at 72%-80%, which is too low and insufficient infertility, and too high aggravates the tendency to shrink.
