DOPAND MATERIAL BASED ON SILICON NITRIDE AND METHOD OF ITS PRODUCTION Russian patent published in 2003 - IPC

FIELD: metallurgy; production of high-nitrogenous ferroalloys. SUBSTANCE: invention relates to high-nitrogenous ferroalloys and in particular to a dopant material based on silicon nitride. The dopant material contains (mass %): silicon nitride of 50-90, ferrous silicides of 5-40, iron of 0.1- 20; at that the weight ratio of chemical elements in the dopant material makes: silicon of 45-75 %, nitrogen of 20-36 %, iron - the rest. The method provide for usage as an initial alloy of ferrosilicon (making 40-95 %), that is comminuted and applied as powder with particle size of no more than 2.5 mm and share of the particles of less than 0.2 mm making no less than 45 %, that is placed in the nitrogen atmosphere under pressure of 0.1-16.5 Mpa. Then the alloy is locally heated up to 1350-2100 C, initiating an exothermic reaction of formation of silicon nitride, saturate with nitrogen in a mode of self-sustaining burning, maintaining the given temperature till the termination of burning; at that the material formed as a result of burning is kept the nitrogen atmosphere under increased pressure for the time duration sufficient for formation of the required contents of silicon nitride in the end product. EFFECT: invention allows to create the dopant material based on silicon nitride with heightened contents of nitrogen and improved operational properties due to quantitative and phase change of its composition. 4 cl, 1 tbl