초록 ▼

Boron nitride is coated on filaments of elemental carbon and/or silicon carbide, the coated filaments are contacted with an infiltration-promoting material containing elemental carbon to produce a preform wherein the filaments are substantially parallel and each filament is enveloped with infiltrati

Boron nitride is coated on filaments of elemental carbon and/or silicon carbide, the coated filaments are contacted with an infiltration-promoting material containing elemental carbon to produce a preform wherein the filaments are substantially parallel and each filament is enveloped with infiltration-promoting material, and the preform is infiltrated with a molten solution of boron and silicon producing a composite containing boron nitride coated filaments.

대표청구항 ▼

A process for producing a composite with a porosity of less than about 10% by volume comprised of boron nitride-coated filaments and a matrix phase, said filament component of said coated filaments comprising at least about 10% by volume of the composite, said matrix phase containing silicon carbide

A process for producing a composite with a porosity of less than about 10% by volume comprised of boron nitride-coated filaments and a matrix phase, said filament component of said coated filaments comprising at least about 10% by volume of the composite, said matrix phase containing silicon carbide and/or boron-containing silicon carbide formed in situ in an amount of at least about 5% by volume of the composite and a solution of elemental boron and elemental silicon in an amount of at least about 1% by volume of the composite, which comprises the following steps: (a) providing a carbon-containing filament having a diameter of at least about 50 microns; (b) depositing a coating of boron nitride on said filament leaving no significant portion thereof exposed; (c) providing infiltration-promoting material in the form of particulates and/or fibers, said infiltration-promoting material containing elemental carbon; (d) contacting a plurality of said boron nitride-coated filaments with said infiltration-promoting material to produce a preform wherein said infiltration-promoting material envelops each coated filament preventing contact therebetween and wherein said coated filaments are at least substantially parallel to each other, said preform having an open porosity ranging from about 25% by volume to about 85% by volume of the preform; (e) providing an infiltrant comprised of boron and silicon containing elemental boron in solution in silicon in an amount of at least about 0.1% by weight of elemental silicon; (f) contacting said preform with infiltrant-associated infiltrating means whereby said infiltrant is infiltrated into said preform; (g) heating the resulting structure to a temperature at which said infiltrant is molten and infiltrating said molten infiltrant into said preform to produce an infiltrated product having the composition of said composite, said preform containing sufficient elemental carbon to react with said infiltrant to form said composite; and (h) cooling said product to produce said composite, said boron nitride-coated filaments being enveloped by said infiltration-promoting material to enable said infiltration by molten infiltrant.