METHOD FOR PRODUCING PRE-CERAMIC FIBER-FORMING OLIGOORGANOSILAZANES Russian patent published in 2022 - IPC C04B35/571 C04B35/589 C04B35/626 C08G77/62 D01F9/10 

FIELD: ceramic materials.

SUBSTANCE: invention relates to a method for producing pre-ceramic fiber-forming oligoorganosilazanes for producing ceramic fibers of the SiCN composition. The reaction mixture of tri- and difunctional organochlorosilanes with their total molar ratio of more than 0.66, but less than 0.85 is subjected to ammonolysis. Ammonolysis is carried out stepwise by sequential introduction of the first, second and third compositions, each of which consists of a mixture of tri- and difunctional organochlorosilanes in toluene. The ammonolysis product is treated with a catalyst and polymerized from 3 to 6 hours at atmospheric and reduced pressure at temperatures of more than 149°C and less than 171°C to obtain polysilazanes with a non-volatile substance content of more than 97, wt. %, with an inorganic residue yield of about 75, wt. %, after pyrolysis up to 1200°C both in an inert atmosphere and in air. This method can be effectively implemented in the industrial production of pre-ceramic fiber-forming oligoorganosilazanes, obtained with high yield and stability in the form of granules for up to 6 months.

EFFECT: fiber-forming polysilazanes provide continuous molding from the melt and ceramization of SiCN fibers with specified characteristics with high physical and mechanical properties.

1 cl, 4 tbl, 10 ex., 2 dwg