METHOD OF PRODUCING COMPOSITE POWDERS BASED ON ALPHA PHASE OF SILICON NITRIDE BY SHS Russian patent published in 2025 - IPC C01B21/68 C01F17/30 B22F3/23 C04B35/587 C04B35/596 

FIELD: chemistry.

SUBSTANCE: invention relates to production of refractory inorganic compounds, which can be used as raw material for production of structural and functional ceramics of high hardness, wear resistance and high-temperature strength, in the automotive and aviation industry for the production of elements of internal combustion engines, lining of combustion chambers, separators of high-temperature bearings, turbine blades, in machine building for production of friction and antifriction bearings. Method of producing composite powders based on the alpha phase of silicon nitride by the SHS method involves preparing a mixture of silicon powders, the alpha phase of silicon nitride and a sintering additive, placing the obtained mixture in a closed SHS reactor, reactor is filled with nitrogen to pressure of 2 MPa, or 3 MPa, or 4 MPa, local ignition of the mixture and synthesis in combustion mode under nitrogen pressure, followed by extraction of the target product. Diluent used is an alpha phase of silicon nitride and/or a synthesis product of the composition alpha-Si₃N₄-R-O-N, where R is Yb, Lu, Sc. Content of the alpha phase of silicon nitride in mixture is 50-75 wt.%, and silicon content is 15-30 wt.%. Sintering additive used is ytterbium, or lutetium, or scandium oxide in amount of 5-20 wt.%. Mixture of powders is prepared in a medium of isopropyl alcohol with subsequent drying of the mixture.

EFFECT: invention enables to obtain sintering-active, metastable composite powders for subsequent production of pore-free fine-grained silicon nitride ceramics by hot pressing, which retains high strength of up to 1,700 °C.

2 cl, 7 ex