Optically translucent ceramic

Claim 2

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 74 weight % Al 2 O 3 balance SiO 2 with a surface area ranging from about 100 square meters per gram to about 400 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 490° C. to about 1100° C. to remove water and any organic material therefrom leaving no significant amount thereof producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 74 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 1.0 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering said compact at a temperature which has no significant deleterious effect on it ranging from about 1500° C. to about 1675° C. in oxygen or in a vacuum ranging from about 0.05 torr to about 1 torr producing a gas-impermeable compact, and hot isostatically pressing said gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1500° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof.

Claim 3

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 74 weight % Al 2 O 3 balance SiO 2 with a surface area ranging from about 200 square meters per gram to about 300 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 500° C. to 700° C. to remove water and any organic material therefrom producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 74 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 1.0 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering the compact at a temperature which has no significant deleterious effect on it at a temperature ranging from about 1600° C. to about 1650° C. in oxygen or in a vacuum from about 0.05 torr to about 1 torr producing a gas-impermeable compact, hot isostatically pressing the gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1600° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof.

Claim 4

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 74 weight % Al 2 O 3 balance SiO 2 with a surface area ranging from about 200 square meters per gram to about 300 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 500° C. to 700° C. to remove water and any organic material therefrom producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 74 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 1.0 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering the compact at a temperature which has no significant deleterious effect on it at a temperature ranging from about 1600° C. to about 1650° C. in oxygen or in a vacuum from about 0.05 torr to about 1 torr producing a gas-impermeable compact, hot isostatically pressing the gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1600° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof.

Claim 5

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 with a surface area ranging from about 100 square meters per gram to about 400 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 490° C. to about 1100° C. to remove water and any organic material therefrom leaving no significant amount thereof producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 0.1 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering the compact at a temperature which has no significant deleterious effect on it at a temperature ranging from about 1500° C. to about 1675° C. in oxygen or in a vacuum ranging from about 0.05 torr to about 1 torr producing a gas-impermeable compact, hot isostatically pressing the gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1500° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said isostatic pressing gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof, and annealing said theoretically dense body in a gas selected from the group consisting of air, oxygen, argon, helium, nitrogen and mixtures thereof at a temperature ranging from about 1700° C. to about 1850° C., said annealing temperature having no significant deleterious effect thereon.

Claim 6

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 with a surface area ranging from about 100 square meters per gram to about 400 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 490° C. to about 1100° C. to remove water and any organic material therefrom leaving no significant amount thereof producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 0.1 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering the compact at a temperature which has no significant deleterious effect on it at a temperature ranging from about 1500° C. to about 1675° C. in oxygen or in a vacuum ranging from about 0.05 torr to about 1 torr producing a gas-impermeable compact, hot isostatically pressing the gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1500° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said isostatic pressing gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof, and annealing said theoretically dense body in a gas selected from the group consisting of air, oxygen, argon, helium, nitrogen and mixtures thereof at a temperature ranging from about 1700° C. to about 1850° C., said annealing temperature having no significant deleterious effect thereon.

Claim 7

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , with a surface area ranging from about 200 square meters per gram to about 300 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 500° C. to 700° C. to remove water and any organic material therefrom producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 1.0 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering said compact at a temperature which has no significant deleterious effect on it ranging from about 1600° C. to about 1650° C. in oxygen or in a vacuum ranging from about 0.05 torr to about 1 torr producing a gas-impermeable compact, hot isostatically pressing said gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1600° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said isostatic pressing gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof, and annealing said theoretically dense body in a gas selected from the group consisting of oxygen, air, argon, helium, nitrogen and mixtures thereof at a temperature ranging from about 1700° C. to about 1850° C., said annealing temperature having no significantly deleterious effect thereon.

Claim 8

A process for producing a mullite body optically translucent in the visible wave length which comprises providing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , with a surface area ranging from about 200 square meters per gram to about 300 square meters per gram and a bulk density ranging from about 0.2 g/cc to about 0.3 g/cc containing a significant amount of water, calcining said powder at a temperature ranging from about 500° C. to 700° C. to remove water and any organic material therefrom producing an amorphous shapeless mixed oxide powder consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said calcining having no significant effect on the oxide composition or morphology of said powder, said calcined powder being pressable at about room temperature into a compact having a minimum density of 1.0 g/cc, pressing said calcined powder into a compact having a minimum density of 1.0 g/cc, sintering said compact at a temperature which has no significant deleterious effect on it ranging from about 1600° C. to about 1650° C. in oxygen or in a vacuum ranging from about 0.05 torr to about 1 torr producing a gas-impermeable compact, hot isostatically pressing said gas-impermeable compact with a gas which has no significant deleterious effect on it at superatmospheric pressure of at least about 5000 psi at a temperature ranging from about 1600° C. to about 1700° C. producing a body of theoretical density based on the density of 3.16 g/cc±0.01 or 3.17 g/cc±0.01 for said mullite body, said isostatic pressing gas being selected from the group consisting of argon, helium, nitrogen and mixtures thereof, and annealing said theoretically dense body in a gas selected from the group consisting of oxygen, air, argon, helium, nitrogen and mixtures thereof at a temperature ranging from about 1700° C. to about 1850° C., said annealing temperature having no significantly deleterious effect thereon.

Claim 9

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said body being of theoretical density based on a density of 3.16 gram/cc±0.01 or 3.17 gram/cc±0.01 for said mullite body, said body ranging from a single phase of mullite to one composed of a primary phase of mullite and a secondary phase ranging up to but less than 1% by volume of the total volume of said body, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 10

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 72.5 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said body being of theoretical density based on a density of 3.16 gram/cc±0.01 or 3.17 gram/cc±0.01 for said mullite body, said body ranging from a single phase of mullite to one composed of a primary phase of mullite and a secondary phase ranging up to but less than 1% by volume of the total volume of said body, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 11

The optically translucent body of claim 5 wherein said secondary phase is Al 2 O 3 .

Claim 12

The optically translucent body of claim 5 wherein said secondary phase is glass.

Claim 13

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 74 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said body having a microstructure comprised of equiaxed or substantially equiaxed grains, said body being of theoretical density based on a density of 3.16 gram/cc±0.01 or 3.17 gram/cc±0.01 for said mullite body, said body ranging from a single phase of mullite to one composed of a primary phase of mullite and a secondary phase ranging up to but less than 1% by volume of the total volume of said body, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 14

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 74 weight % to about 76.5 weight % Al 2 O 3 balance SiO 2 , said body having a microstructure comprised of equiaxed or substantially equiaxed grains, said body being of theoretical density based on a density of 3.16 gram/cc±0.01 or 3.17 gram/cc±0.01 for said mullite body, said body ranging from a single phase of mullite to one composed of a primary phase of mullite and a secondary phase ranging up to but less than 1% by volume of the total volume of said body, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 15

The optically translucent body of claim 8 wherein said secondary phase is Al 2 O 3 .

Claim 16

The optically translucent body of claim 8 wherein said secondary phase is glass.

Claim 17

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 72.5 weight % up to about 74.5 weight % Al 2 O 3 balance SiO 2 , said body having a microstructure ranging from one composed of elongated grains to one composed of equiaxed grains and all combinations thereof, said body being of theoretical density based on a density of 3.16 grams/cc±0.01 or 3.17 grams/cc±0.01 for said mullite body, said body ranging from a single phase of mullite to one composed of a primary phase of mullite and a secondary phase ranging up to but less than 1% by volume of the total volume of said body, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 18

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 72.5 weight % up to about 74.5 weight % Al 2 O 3 balance SiO 2 , said body having a microstructure ranging from one composed of elongated grains to one composed of equiaxed grains and all combinations thereof, said body being of theoretical density based on a density of 3.16 grams/cc±0.01 or 3.17 grams/cc±0.01 for said mullite body, said body ranging from a single phase of mullite to one composed of a primary phase of mullite and a secondary phase ranging up to but less than 1% by volume of the total volume of said body, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 19

The optically translucent body of claim 11 wherein said secondary phase is glass.

Claim 20

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 74.5 weight % to about 75.5 weight % Al 2 O 3 balance SiO 2 , said body having a substantially uniform microstructure comprised of equiaxed or substantially equiaxed grains, said body being of theoretical density based on a density of 3.16 gram/cc±0.01 or 3.17 gram/cc±0.01 for said mullite body, said body being composed of a single phase of mullite, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 21

A polycrystalline mullite body optically translucent in the visible wave length consisting essentially of from about 74.5 weight % to about 75.5 weight % Al 2 O 3 balance SiO 2 , said body having a substantially uniform microstructure comprised of equiaxed or substantially equiaxed grains, said body being of theoretical density based on a density of 3.16 gram/cc±0.01 or 3.17 gram/cc±0.01 for said mullite body, said body being composed of a single phase of mullite, and said body having an average minimum forward diffuse transmittance of 70% at 0.75 millimeter of thickness over the wave lengths ranging from 4000 Angstroms to 8000 Angstroms.

Claim 22

The process according to claim 1 wherein said compact is of hollow and/or geometrically complex shape.

Claim 23

The process according to claim 3 wherein said compact is of hollow and/or geometrically complex shape.

Claim 24

The body of claim 5 being of hollow and/or geometrically complex shape.

Claim 25

The body of claim 8 being of hollow and/or geometrically complex shape.

Claim 26

The body of claim 11 being of hollow and/or geometrically complex shape.

Claim 27

The body of claim 13 being of hollow and/or geometrically complex shape.