Ferrosilicon nitride (Fe-Si3N4) is a new type of nitride raw material synthesized at high temperature using nitriding technology. It is the product of nitriding ferrosilicon alloy powder by heating it to 1200~1400℃ in a chemical atmosphere. Its main component is 75%~80% (w) silicon nitride, and it also contains free iron and unnitrided FeSi.
During the ferrosilicon nitriding reaction, the reaction itself is highly exothermic, and iron plays the role of a catalyst; the finer the ferrosilicon size, the larger the specific surface area, the faster and more intense the reaction, and the ferrosilicon particles are severely sintered, resulting in difficulty in nitrogen diffusion and poor nitriding effect.
For coarse ferrosilicon particles, the porosity is large, the specific surface area is small, the nitriding reaction is stable, and the nitriding is safer as the temperature rises.
Using finer ferrosilicon powder for nitriding treatment will cause rapid and intense reactions, which will also lead to severe sintering and poor nitriding effect; on the contrary, if coarser ferrosilicon powder is used, the nitriding effect is better. Finer ferrosilicon powder is easy to form whisker-like, fibrous and columnar silicon nitride crystals after nitriding, while coarser ferrosilicon powder is easy to form spherical silicon nitride agglomerates after nitriding.
In addition to being used in the steelmaking industry, ferrosilicon can also be used in cast iron, and as an inoculant for ductile iron, it prevents carbide formation, promotes graphite precipitation and spheroidization, and improves cast iron performance.
