Graphite fiber growth employing nuclei derived from iron pentacarbonyl

Claim 2

In a method for manufacturing carbon filaments by pyrolysis of a faseous hydrocarbon compound in the presence of iron nuclei, the improvement comprising forming the iron nuclei prior to initiation of said gaseous hydrocarbon pyrolysis by heating a gas containing iron pentacarbonyl vapors at a temperature between 300° C. and 500° C. to decompose the iron pentacarbonyl to produce iron particles having diameters less than 0.1 micron and suitable for use as the nuclei for forming the carbon filaments.

Claim 3

In a method for manufacturing graphite fibers by pyrolysis of a gaseous hydrocarbon compound in the presence of iron nuclei distributed upon a suitable growing surface, whereupon said nuclei react with pyrolytic carbon derived from the hydrocarbon compound to grow microscopic carbon filaments suitable for thickening into product fibers, the improvement comprising forming the iron nuclei by exposing the surface to a gas containing iron pentacarbonyl vapors and heating at a temperature between 300° C. and 500° C. to decompose the iron pentacarbonyl to produce iron particles that deposit onto the surface and suitable for use as a nuclei for forming the carbon filaments.

Claim 4

In a method for manufacturing graphite fibers by pyrolysis of a gaseous hydrocarbon compound in the presence of iron nuclei distributed upon a suitable growing surface, whereupon said nuclei react with pyrolytic carbon derived from the hydrocarbon compound to grow microscopic carbon filaments suitable for thickening into product fibers, the improvement comprising forming the iron nuclei by exposing the surface to a gas containing iron pentacarbonyl vapors and heating at a temperature between 300° C. and 500° C. to decompose the iron pentacarbonyl to produce iron particles that deposit onto the surface and suitable for use as a nuclei for forming the carbon filaments.

Claim 5

In a method for manufacturing graphite fibers by methane pyrolysis in the presence of particulate iron nuclei distributed upon a suitable growing surface, which method comprises contacting the nuclei-bearing surface with a hydrogen gas stream comprising about 5 to 15 volume percent methane from a natural gas source at a temperature sufficient to decompose the methane and react carbon derived thereby with the iron nuclei to grow microscopic carbon filaments, and thereafter contacting the filaments with a gas comprising at least 25 volume percent methane from a natural gas source at a temperature sufficient to deposit additional pyrolytic carbon to thicken the filaments to form the product fibers, the improvement comprising depositing, prior to methane pyrolysis, iron nuclei onto the surface by passing into contact therewith a predominantly inert gas stream containing iron pentacarbonyl vapors while heating at a temperature between 300° C. and 400° C. to decompose the iron pentacarbonyl to produce iron particles having diameters less than 0.1 micron that deposit onto the surface and form the nuclei.

Claim 6

In a method for manufacturing graphite fibers by methane pyrolysis in the presence of particulate iron nuclei distributed upon a suitable growing surface, which method comprises contacting the nuclei-bearing surface with a hydrogen gas stream comprising about 5 to 15 volume percent methane from a natural gas source at a temperature sufficient to decompose the methane and react carbon derived thereby with the iron nuclei to grow microscopic carbon filaments, and thereafter contacting the filaments with a gas comprising at least 25 volume percent methane from a natural gas source at a temperature sufficient to deposit additional pyrolytic carbon to thicken the filaments to form the product fibers, the improvement comprising depositing, prior to methane pyrolysis, iron nuclei onto the surface by passing into contact therewith a predominantly inert gas stream containing iron pentacarbonyl vapors while heating at a temperature between 300° C. and 400° C. to decompose the iron pentacarbonyl to produce iron particles having diameters less than 0.1 micron that deposit onto the surface and form the nuclei.

Claim 7

In a method for manufacturing graphite fibers by methane pyrolysis in the presence of particulate iron nuclei entrained within a gas stream, said gas stream comprising methane from a natural gas source, the improvement comprising dispersing iron pentacarbonyl vapors into the gas stream prior to methane pyrolysis while heating at a temperature between about 300° C. and 400° C. decompose the iron pentacarbonyl to produce iron particles having diameters less than 0.1 micron that become entrained in the gas stream to form the nuclei.

Claim 8

In a method for manufacturing graphite fibers by methane pyrolysis in the presence of particulate iron nuclei entrained within a gas stream, said gas stream comprising methane from a natural gas source, the improvement comprising dispersing iron pentacarbonyl vapors into the gas stream prior to methane pyrolysis while heating at a temperature between about 300° C. and 400° C. decompose the iron pentacarbonyl to produce iron particles having diameters less than 0.1 micron that become entrained in the gas stream to form the nuclei.