US4536379A — Production of silicon carbide

Claim 1

Independent Claim 117 words

A process for the production of silicon carbide crystals and whiskers comprising reacting at a temperature of between about 1,400° C. to about 2,100° C. and in the presence of an inert gas, a mined material of nature referred to herein as Black Diamond having as essential ingredients, carbon, silica, aluminum, iron oxide, potassium oxide, volatiles and moisture wherein a typical composition based on weight, comprises about 3% moisture, about 33% carbon, about 8% volatiles, and about 56% ash, said ash including, based on the weight of the ash, about 76.8% silica, about 12.9% alumina, about 4.6% iron oxide, and about 2.4 potassium oxide, and said typical composition providing a carbon to silicon ratio of about 1.57:1.

Claim 2

Dependent Claim 117 words

A process for the production of silicon carbide crystals and whiskers comprising reacting at a temperature of between about 1,400° C. to about 2,100° C. and in the presence of an inert gas, a mined material of nature referred to herein as Black Diamond having as essential ingredients, carbon, silica, aluminum, iron oxide, potassium oxide, volatiles and moisture wherein a typical composition based on weight, comprises about 3% moisture, about 33% carbon, about 8% volatiles, and about 56% ash, said ash including, based on the weight of the ash, about 76.8% silica, about 12.9% alumina, about 4.6% iron oxide, and about 2.4 potassium oxide, and said typical composition providing a carbon to silicon ratio of about 1.57:1.

Claim 3

Dependent Claim 21 words

The process according to claim 1, and reacting said material at a temperature of between about 1,800° C. and 2,100° C.

Claim 4

Dependent Claim 45 words

The process according to claim 2, and adding additional silica to a given quantity of said material of nature in an amount which together with said given quantity provides a carbon to silicon ratio of from about 0.84:1 to about 2.17:1 for the total composition.

Claim 5

Dependent Claim 32 words

The process according to claim 3, wherein said additional silica is in an amount to provide a carbon to silicon ratio of from about 0.84:1 to about 1.57:1 for said total composition.

Claim 6

Dependent Claim 32 words

The process according to claim 3, wherein said additional silica is in an amount to provide a carbon to silicon ratio of from about 1.06:1 to about 1.26:1 for said total composition.

Claim 7

Dependent Claim 27 words

The process according to claim 3, wherein said additional silica is in an amount to provide a carbon to silicon ratio of about 1.06:1 said total composition.

Claim 8

Dependent Claim 28 words

The process according to claim 3, and seeding said total composition with silicon carbide in an amount of about 1% of the total weight of said total composition.

Claim 9

Dependent Claim 32 words

The process according to claim 7, wherein said additional silica is in an amount to provide a carbon to silicon ratio of from about 0.84:1 to about 1.26:1 for said total composition.

Claim 10

Dependent Claim 65 words

The process according to claim 1, wherein said reaction takes place in a stationary furnace having input and discharge ends and said process includes the steps of maintaining said furnace at a temperature of from about 1,800° C. to about 2,100° C., placing said material in an open top carbon receptacle, and advancing said receptacle through said furnace from said input to said discharge end.

Claim 11

Dependent Claim 29 words

The process according to claim 9, and flowing said inert gas through said furnace at a flow rate of from about 5 to about 10 cubic feet per hour.

Claim 12

Dependent Claim 22 words

The process according to claim 10, and advancing said receptacle through said furnace to provide a process time of about 228 minutes.

Claim 13

Dependent Claim 44 words

The process according to claim 1, and adding silica to a given quantity of said material of nature in an amount which together with said given quantity provides a carbon to silicon ratio of from about 0.84:1 to about 2.17:1 for the total composition.

Claim 14

Dependent Claim 30 words

The process according to claim 12, wherein said additional silica in an amount providing a carbon to silicon ratio of from about 1.06:1 to about 1.26:1 for said total composition.

Claim 15

Dependent Claim 27 words

The process according to claim 12, wherein said additional silica in an amount providing a carbon to silicon ratio of from about 1.06:1 for said total composition.

Claim 16

Dependent Claim 21 words

The process according to claim 12, and reacting said material at a temperature of between about 1,800° C. and 2,100° C.

Claim 17

Dependent Claim 137 words

A process for making silicon carbide in crystal and whisker forms in yields greater than about 75% based on the conversion to silicon carbide of the total weight amount of silica and carbon in the reactants comprising the steps of: selecting as one of the reactants a mined material of nature referred to herein as Black Diamond containing as essential ingredients carbon, silica, alumina, iron oxide and potassium oxide; adding to said one of the reactants, as required, additional reactants selected from the group of carbon, silica and silicon carbide in amounts sufficient to provide a carbon to silicon ratio of about 0.84 to 1.57 based on the total weights of the reactants; and, reacting said material of nature and said additional reactants in an inert environment at a temperature of around 1800° C. to 2100° C.

Claim 18

Dependent Claim 137 words

A process for making silicon carbide in crystal and whisker forms in yields greater than about 75% based on the conversion to silicon carbide of the total weight amount of silica and carbon in the reactants comprising the steps of: selecting as one of the reactants a mined material of nature referred to herein as Black Diamond containing as essential ingredients carbon, silica, alumina, iron oxide and potassium oxide; adding to said one of the reactants, as required, additional reactants selected from the group of carbon, silica and silicon carbide in amounts sufficient to provide a carbon to silicon ratio of about 0.84 to 1.57 based on the total weights of the reactants; and, reacting said material of nature and said additional reactants in an inert environment at a temperature of around 1800° C. to 2100° C.

Claim 19

Dependent Claim 32 words

The process according to claim 16, wherein said additional reactants include silica in an amount providing a carbon to silicon ratio of from about 0.84:1 to about 1.57:1 for said total composition.

Claim 20

Dependent Claim 27 words

The process according to claim 16, wherein said additional reactants includes silicon carbide in an amount of about 1% of the total weight of said total composition.

Claim 21

Dependent Claim 32 words

The process according to claim 18, wherein said additional reactants include silica in an amount providing a carbon to silicon ratio of from about 0.84:1 to about 1.26:1 for said total composition.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1988-08-19	1989-02-18	1989-08-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1992-08-19	1993-02-18	1993-08-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1996-08-19	1997-02-18	1997-08-20	$7700.00	Window Closed / Lapsed

Production of silicon carbide

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