Silicon carbide-graphite composite material

Claim 2

A silicon carbide-graphite composite material in the as sintered state which is produced by a process comprising the steps of: adding a sintering aid to α-silicon carbide of an average grain size less than 1 μm, said sintering aid comprising not less than 0.1 wt% and less than 1.0 wt% of a compound selected from the group consisting of boron and a boron compound which includes a corresponding amount of boron; and 0.1 to 6.0 wt% of a compound selected from the group consisting of organic carbonaceous compounds which includes a corresponding amount of carbon each based on the weight of silicon carbide; further adding carbon black to α-silicon carbide in an amount of 1 to 20 vol% based on the volume of the silicon carbide as a silicon carbide grain growth inhibitor; blending the compositions into an intimate mixture; molding the intimate mixture to obtain a molded body; and sintering the molded body at about atmospheric pressure.

Claim 3

A silicon carbide-graphite composite material in the as sintered state, comprising: a silicon carbide comprising less than 1.0 wt% of a compound selected from the group consisting of boron and a boron compound which includes a corresponding amount of boron as a primary phase; and graphite as a secondary phate having an average grain size of not more than 3 μm segregated along the grain boundaries of all the silicon carbide grains in the composite material in a proportion of 1 to 20 vol% based on the volume of silicon carbide, said composite material having a density greater than 90% of theoretical density; which is produced by a process comprising the steps of: adding a sintering aid to α-silicon carbide of an average grain size less than 1 μm, said sintering aid comprising not less than 0.1 wt% and less than 1.0 wt% of a compound selected from the group consisting of boron and a boron compound which includes a corresponding amount of boron; and 0.1 to 6.0 wt% of a compound selected from the group consisting of organic carbonaceous compounds which includes a corresponding amount of carbon each based on the weight of silicon carbide; further adding carbon black as a silicon carbide grain growth inhibitor to α-silicon carbide in an amount of 1 to 20 vol% based on the volume of the silicon carbide; blending the compositions into an intimate mixture; molding the mixture to obtain a molded body; and sintering the molded body at about atmospheric pressure.

Claim 4

A silicon carbide-graphite composite material in the as sintered state, comprising: a silicon carbide comprising less than 1.0 wt% of a compound selected from the group consisting of boron and a boron compound which includes a corresponding amount of boron as a primary phase; and graphite as a secondary phate having an average grain size of not more than 3 μm segregated along the grain boundaries of all the silicon carbide grains in the composite material in a proportion of 1 to 20 vol% based on the volume of silicon carbide, said composite material having a density greater than 90% of theoretical density; which is produced by a process comprising the steps of: adding a sintering aid to α-silicon carbide of an average grain size less than 1 μm, said sintering aid comprising not less than 0.1 wt% and less than 1.0 wt% of a compound selected from the group consisting of boron and a boron compound which includes a corresponding amount of boron; and 0.1 to 6.0 wt% of a compound selected from the group consisting of organic carbonaceous compounds which includes a corresponding amount of carbon each based on the weight of silicon carbide; further adding carbon black as a silicon carbide grain growth inhibitor to α-silicon carbide in an amount of 1 to 20 vol% based on the volume of the silicon carbide; blending the compositions into an intimate mixture; molding the mixture to obtain a molded body; and sintering the molded body at about atmospheric pressure.

Claim 5

A silicon carbide-graphite material as in claim 2, wherein the graphite has been derived from the carbon black upon production of the composite material.

Claim 6

A silicon carbide-graphite material as in claim 1, said composite material having improved shock resistance and bending strength and a reduced coefficient of kinetic friction.

Claim 7

A silicon carbide-graphite material as in claim 3, said composite material having improved shock resistance and bending strength and a reduced coefficient of kinetic friction.

Claim 8

A silicon carbide graphite composite material as claimed in claim 4, said graphite which comprises the secondary phase of the composite material having a high heat resistance and not impairing the chemical stability of the silicon carbide.

Claim 9

A silicon carbide graphite composite material as claimed in claim 3, said graphite which comprises the secondary phase of the composite material having a high heat resistance and not impairing the chemical stability of the silicon carbide.

Claim 10

A silicon carbide graphite composite material as claimed in claim 1, wherein said carbonaceous compound reacts with silica during sintering and does not remain in the composite material after sintering.

Claim 11

A silicon carbide graphite composite material as claimed in claim 3, wherein said carbonaceous compound reacts with silica during sintering and does not remain in the composite material after sintering.

Claim 12

A silicon carbide graphite composite material as claimed in claim 1, wherein said carbonaceous compound comprises a phenolic resin.

Claim 13

A silicon carbide graphite composite material as claimed in claim 2, wherein said organic carbonaceous compound comprises a phenolic resin.

Claim 14

A silicon carbide graphite composite material as claimed in claim 5, wherein said organic carbonaceous compound comprises a phenolic resin.

Claim 15

A silicon carbide graphite composite material as claimed in claim 1, wherein said organic carbonaceous compound is one which can supply carbon obtained by decomposition of an organic compound for use as a carbon component of the sintering aid.

Claim 16

A silicon carbide graphite composite material as claimed in claim 2, wherein said organic carbonaceous compound is one which can supply carbon obtained by decomposition of an organic compound for use as a carbon component of the sintering aid.

Claim 17

A silicon carbide-graphite composite material as claimed in claim 1, wherein said sintering aid contains the boron.

Claim 18

A silicon carbide-graphite composite material as claimed in claim 1, wherein said sintering aid contains the boron compound which includes a corresponding amount of boron.

Claim 19

A silicon carbide-graphite composite material as claimed in claim 1, wherein said sintering aid contains the carbonaceous compound which includes a corresponding amount of carbon.