Refractory composites

Claim 2

A composite as defined in claim 1, wherein said boride is hafnium diboride and said silicide is tungsten disilicide.

Claim 3

A composite as defined in claim 2, wherein said boride is hafnium diboride and said silicide is tungsten disilicide.

Claim 4

A composite as defined in claim 4, consisting essentially of, by weight, 66 percent hafnium diboride, 20 percent tungsten disilicide and 14 percent graphite fibers.

Claim 5

An article comprising a high temperature resistant substrate containing a bonded coating comprising a composite consisting essentially of, by weight (a) about 40 to about 70 percent of a boride selected from the group consisting of hafnium diboride, zirconium diboride and titanium diboride, and mixtures thereof, (b) about 16 to about 50 percent of a silicide selected from the group consisting of tungsten disilicide and molybdenum disilicide, and mixtures thereof, and (c) about 10 to about 16 percent by weight of discrete carbon particles selected from the group consisting of graphite, amorphous carbon and pyrolytic graphite, and mixtures thereof, said composite being substantially free of silicon carbide, said boride and said silicide forming a matrix, said carbon particles being dispersed in said matrix.

Claim 6

An article as defined in claim 6, said substrate being selected from the group consisting of metals, metal alloys, carbon and graphite.

Claim 7

An article as defined in claim 6, said substrate being selected from the group consisting of tantalum, tungsten, tantalum alloys conTaining tungsten, nickel and cobalt alloys, steel and steel alloys, and graphite.

Claim 8

An article as defined in claim 8, said carbon particles of said composite being graphite fibers.

Claim 9

An article as defined in claim 9, said boride of said composite being hafnium diboride and said silicide being tungsten disilicide.

Claim 10

An article as defined in claim 10, said composite consisting essentially of about 66 percent hafnium diboride, about 20 percent tungsten disilicide and about 14 percent of said graphite fibers.

Claim 11

An article as defined in claim 11, said substrate being tantalum.

Claim 12

An article as defined in claim 6, said substrate being a high temperature resistant metal container containing therein an isotope fuel block, said composite coating being integrally bonded to the entire outer surface of said container.

Claim 13

An article as defined in claim 12, said substrate being a high temperature resistant metal container containing therein an isotope fuel block, said composite coating being integrally bonded to the entire outer surface of said container.

Claim 14

The process of producing an article comprising a substrate containing a high strength, oxidation and temperature resistant, and high density refractory coating, comprising hot pressing at temperature ranging from about 1,200* to about 2,200*C against a surface of a high temperature resistant substrate, a mixture consisting essentially of, by weight (a) about 40 to about 70 percent of a boride selected from the group consisting of hafnium diboride, zirconium diboride and titanium diboride, and mixtures thereof, (b) about 16 to about 50 percent of a silicide selected from the group consisting of tungsten disilicide and molybdenum disilicide, and mixtures thereof, and (c) about 10 to about 16 percent of discrete carbon particles selected from the group consisting of graphite, amorphous carbon and pyrolytic graphite, and mixtures thereof, said hot pressed mixture being substantially free of silicon carbide, to form an integral bonded composite coating of said hot pressed mixture on said substrate, said boride and said silicide of said composite forming a matrix, said carbon particles being dispersed in said matrix.

Claim 15

A process as defined in claim 15, said substrate being selected from the group consisting of metals, metal alloys, carbon and graphite.

Claim 16

A process as defined in claim 16, employing pressures during said hot pressing ranging from about 2,000 to about 20,000 psi for a period ranging from about 3 to about 60 minutes.

Claim 17

A process as defined in claim 17, said boride of said mixture being hafnium diboride and said silicide being tungsten disilicide, and said carbon particles being graphite fibers.

Claim 18

A process as defined in claim 18, said mixture consisting essentially of about 66 percent hafnium diboride, about 20 percent tungsten disilicide, and about 14 percent graphite fibers, by weight.

Claim 19

A process as defined in claim 18, said hot pressing being carried out in a hot press under vacuum corresponding to a pressure of about 1 micron to about 400 mm mercury of an inert gas.

Claim 20

A process as defined in claim 20, said hot pressing being carried out at about 2,100*C, and at about 4,000 psi pressure, for a period of about 15 minutes, said hot press being under a vacuum corresponding to a pressure of about 1 to about 5 microns.

Claim 21

A process as defined in claim 21, said substrate being tantalum.

Claim 22

A process as defined in claim 15, employing a high temperature resistant metal substrate, including first applying an adhesive to said substrate, and then coating over said adhesive an initial coating of a fine powder of a substance selected from the group consisting of hafnium diboride, titanium diboride, zirconium diboride, tungsten disilicide, iridium and rhenium, and mixtures thereof.

Claim 23

A proceSs as defined in claim 22, employing a high temperature resistant metal substrate, including first applying an adhesive to said substrate, and then coating over said adhesive an initial coating of a fine powder of a substance selected from the group consisting of hafnium diboride, titanium diboride, zirconium diboride, tungsten disilicide, iridium and rhenium, and mixtures thereof.

Claim 24

A process as defined in claim 15, said substrate being a high temperature resistant metal container containing therein an isotope fuel block, said composite coating being integrally bonded to the entire outer surface of said container; said composite coating, said container and said isotope fuel block being simultaneously consolidated into a unitary compact during said hot pressing.

Claim 25

A process as defined in claim 23, said substrate being a high temperature resistant metal container containing therein an isotope fuel block, said composite coating being integrally bonded to the entire outer surface of said container; said composite coating, said container and said isotope fuel block being simultaneously consolidated into a unitary compact during said hot pressing.

Claim 26

A process as defined in claim 24, said substrate being a high temperature resistant metal container containing therein an isotope fuel block, said composite coating being integrally bonded to the entire outer surface of said container; said composite coating, said container and said isotope fuel block bieng simultaneously consolidated into a unitary compact during said hot pressing.