METHOD OF PRODUCING SILICON NITRIDE-BASED SINTERED ARTICLES Russian patent published in 2012 - IPC C04B35/591 

FIELD: chemistry.

SUBSTANCE: invention relates to production of articles from silicon nitride-based high-temperature structural materials which can be used in machine-building, aviation and other high-technology industries. The method of producing silicon nitride-based sintered articles involves: preparation of a starting mixture containing silicon nitride powder and a process additive, moulding the article, putting the article into a reactor, filling the article with a layer of an exothermic mixture containing silicon nitride in amount of 45.0-65.0 wt % and silicon in amount of 35.0-55.0 wt %, initiating combustion and thermal treatment in combustion conditions at nitrogen pressure from 5 to 35 MPa. The process additive used is Al₂O₃, Y₂O₃, mullite, yttrium aluminium garnet, calcium aluminate, yttrium aluminosilicate in amount of 5-15 wt %. The mixture contains silicon nitride power obtained via plasmochemical, pyrochemical or self-propagating high-temperature synthesis with specific surface area of not less than 5 m²/g. Not more than 30 wt % silicon powder can further be added to the starting mixture. The exothermic mixture for filling can further contain a group II-III metal oxide, preferably MgO, Y₂O₃, Al₂O₃, in amount of not more than 15 wt %.

EFFECT: obtaining articles with high mechanical strength and density.

4 cl, 9 ex