Ferro silicon nitride is a ferroalloy material mainly composed of Si3N4, accompanied by free iron, non-silicon nitride, and a small number of other components. Commercial ferrosilicon nitride for refractory is an off-white or brown powder, while steel-making ferrosilicon nitride is off-white granular.
Powdered ferrosilicon nitride is mainly used in the tap hole of large blast furnaces, and a small amount is used in iron runner materials or other unshaped refractory materials. Granular ferrosilicon nitride is mainly used in silicon-oriented steel or other steels (Such as HRB400 rebar) that use nitrides to improve strength.
Differences between ferro silicon nitride and silicon nitride
The uses of ferrosilicon nitride and silicon nitride are very similar, but their main components are different. Ferro silicon nitride is accompanied by free iron, but silicon nitride contains very little iron.
The price of ferrosilicon nitride is about half of that of silicon nitride, and the performance of the two is nearly the same.
Chemical composition comparison of ferro silicon
| Chemical Composition (%) | Si3N4 | Si | N | Fe | Al+Ca |
| Element Content | 75~80 | 47~51 | 30~33 | 12~16 | <2.5 |
| Element Content | 70~75 | 49~52 | 28~30 | 12~16 | <2.5 |
| Granular Product | Grain Diameter | Percentage |
| Fine Grain | 3~5 mm | >90 |
| Common Grain | 3~10mm | >90 |
| Coarse Grain | 10~50mm | >90 |
Note: It can be customized into 10-100mm or 0-20 mesh in a lump, grain, and powder.
Application of ferro silicon nitride
The main application of ferro silicon nitride
- Unshaped refractory materials, non-foaming tap hole mud, iron runner materials.
- Nitrogen increasing agent: By mixing with iron vanadium nitride, ferrosilicon nitride, ferroniobium, ferrochromium, etc. to replace vanadium-nitrogen alloy, reduce the cost of nitrogen increasing agent.
| Product | N | Si | Fe | O | Water | granularity |
| FeSi3N4 | 28-32% | 48-52% | 12-17% | 2.5% max | 0.3% max | 0-50mm Special granularity can be customized |
Chemical composition of ferrosilicon nitride used as the nitrogen increasing agent
Properties of ferrosilicon nitride
Ferrosilicon nitride is an emerging high-quality refractory raw material, which can replace the higher price of silicon nitride and is used in the tap hole mud of large blast furnaces. It has good opening properties, sintering aid, corrosion resistance, and low-cost characteristics.
In all cases, the introduction of ferrosilicon nitride improves the high-temperature strength and wear resistance of refractory materials, improves their thermal stability and oxidation resistance, and reduces the thermal expansion coefficient while increasing the thermal conductivity. It is also important that refractories are more resistant to wear from hot metals and slag. In addition, the refractory material does not shrink when heated repeatedly. The tap hole mud containing ferrosilicon nitride is most effective for the tap hole of the closed furnace with a large working space.
Advantages of ferrosilicon nitride
- Improve the high-temperature strength and wear resistance of refractory materials, improve the thermal stability and oxidation resistance, and reduce the thermal expansion coefficient, while increasing the thermal conductivity.
- Compared with the traditional manganese and chromium alloys used for alloying, the consumption of ferrosilicon nitride is much less.
Types of ferro silicon nitride
According to different forms of classifications, ferro silicon nitride can be categorized into different types.
According to the use of ferrosilicon nitride, it can be divided into two types: ferrosilicon nitride for refractory materials and ferrosilicon nitride for steelmaking. The grain size of ordinary ferrosilicon nitride for refractory materials is 200 mesh, while the grain size of stabilized ferrosilicon nitride for refractory materials is 325 mesh. The surface of ferrosilicon nitride for steelmaking also needs to be clean, and there should be no obvious foreign matter.
According to physical characteristics, it can be divided into ordinary ferrosilicon nitride for refractory materials and stabilized ferrosilicon nitride for refractory materials. Ferrosilicon nitride for steelmaking can be classified as ordinary ferrosilicon nitride and high-purity ferrosilicon nitride.
Ordinary ferrosilicon nitride is off-white, stable ferrosilicon nitride is dark brown, and the surface of refractory material uses is clean without obvious foreign debris.
The preparation of ferrosilicon nitride
Ferrosilicon nitride is usually synthesized with ferrosilicon alloy or monatomic silicon at high temperatures using nitriding technology. In the synthesis process, the following two factors greatly affect the synthesis effect.
- Ferrosilicon granularity: the relationship between the nitrogen content of products with different particle sizes and the reaction temperature.
The finer the ferrosilicon, the smaller the porosity of the sample, the larger the specific surface area, and the faster and more intense the reaction. However, the more severe the sintering between ferrosilicon particles, the worse the nitrogen diffusion and the worse the nitriding effect. The specific surface area of the coarse-grained sample is small, the nitriding reaction is more stable, and the nitriding becomes more sufficient as the temperature rises.
- Nitriding temperature: High-temperature nitriding is more complete than low-temperature nitriding