Silicon manganese nitride is an important additive in steel. The presence of silicon manganese nitride can improve the hot processing performance of steel, improve the strength of pearlitic steel, and also improve the hardenability of steel; it also has high temperature thermal stability, thermal shock resistance, hot and cold shock resistance, and chemical resistance. Stability, good electrical insulation and hardness.
As a new, effective and economical alloy additive, silicon manganese nitride has been accepted by the majority of steel companies and users. The method of nitriding under normal pressure is to use industrial silicon manganese and ferrosilicon as raw materials, and to prepare silicon manganese nitride by flowing nitrogen gas at high temperature.
The conversion temperature value of silicon manganese in the nitriding preparation process is 1478K (1205°C); the reaction mechanism of the nitriding reaction of ferrosilicon alloy and Fe can promote the nitriding reaction; the reaction mechanism of nitriding silicon in the raw material to generate silicon nitride. Factors that affect the nitrogen content of the product include reaction temperature, reaction time, ratio coefficient of raw materials, reactant particle size, nitrogen system, and types of additives.
When the nitridation reaction is carried out at 1200°C, constant temperature for 3 hours, the ratio of silicon to manganese reaches 3/8, and the nitrogen flow rate is 3L/min, the nitrogen content of the product is very high, which can reach 26%. Five additives (iron powder, ferric chloride, calcium carbonate, ammonium chloride and ammonium carbonate) have little effect on the increase in nitrogen content. Three groups of improvement experiments (adding inducers, heating in stages, and only using silicon manganese as raw materials) all The nitrogen content of silicon manganese nitride is not significantly increased.
When the reaction is between 600 and 1250°C, the apparent activation energy is low, so the reaction can easily occur at a lower temperature; when the reaction is between 1250 and 1275°C, the apparent activation energy is high and the reaction is difficult to occur.
