Method for the preparation of an inorganic fiber containing silicon, carbon, boron and nitrogen

Claim 1

A method for the preparation of an inorganic fiber comprising the elements of silicon, carbon, boron and nitrogen which comprises the steps of: (a) heating a reaction mixture composed of an organosilicon compound having, in a molecule, at least one silicon-to-silicon linkage and at least one group denoted by R 1 , R 1 being a hydrogen atom or a monovalent hydrocarbon group selected from the class consisting of methyl, ethyl, vinyl and phenyl groups, bonded to the silicon atom and an organoboron compound represented by the unit formula --BR 2 --NR 3 --, in which R 2 is a monovalent group selected from the class consisting of monovalent hydrocarbon groups, trihydrocarbylsilyl-substituted alkyl groups of the formula --CH 2 ) n SiR 4 3 , R 4 being a monovalent hydrocarbon group and n being a positive integer, and substituted or unsubstituted amino groups of the formula --NR 5 2 , R 5 being a hydrogen atom or a monovalent hydrocarbon group, and R 3 is a monovalent hydrocarbon group, in the molar ratio of silicon to boron in the range from 2:1 to 200:1 at a temperature in the range from 250° to 500° C. in an inert atmosphere to effect the thermal decomposition and polycondensation reaction of the reactants forming an organoborosilicon polymer having a number-average molecular weight in the range from 1,000 to 50,000; (b) spinning the organoborosilicon polymer into a fibrous form; (c) infusibilizing the thus formed fiber of the organoborosilicon polymer; and (d) calcining the infusibilized fiber of the organoborosilicon polymer at a temperature in the range from 900° to 1800° C. in an atmosphere of vacuum or an inert gas.

Claim 2

A method for the preparation of an inorganic fiber comprising the elements of silicon, carbon, boron and nitrogen which comprises the steps of: (a) heating a reaction mixture composed of an organosilicon compound having, in a molecule, at least one silicon-to-silicon linkage and at least one group denoted by R 1 , R 1 being a hydrogen atom or a monovalent hydrocarbon group selected from the class consisting of methyl, ethyl, vinyl and phenyl groups, bonded to the silicon atom and an organoboron compound represented by the unit formula --BR 2 --NR 3 --, in which R 2 is a monovalent group selected from the class consisting of monovalent hydrocarbon groups, trihydrocarbylsilyl-substituted alkyl groups of the formula --CH 2 ) n SiR 4 3 , R 4 being a monovalent hydrocarbon group and n being a positive integer, and substituted or unsubstituted amino groups of the formula --NR 5 2 , R 5 being a hydrogen atom or a monovalent hydrocarbon group, and R 3 is a monovalent hydrocarbon group, in the molar ratio of silicon to boron in the range from 2:1 to 200:1 at a temperature in the range from 250° to 500° C. in an inert atmosphere to effect the thermal decomposition and polycondensation reaction of the reactants forming an organoborosilicon polymer having a number-average molecular weight in the range from 1,000 to 50,000; (b) spinning the organoborosilicon polymer into a fibrous form; (c) infusibilizing the thus formed fiber of the organoborosilicon polymer; and (d) calcining the infusibilized fiber of the organoborosilicon polymer at a temperature in the range from 900° to 1800° C. in an atmosphere of vacuum or an inert gas.