Ceramic-metal systems by infiltration

Abstract

This invention covers ceramic-metal compositions fabricated by infiltrating porous ceramic compact with a molten metal impregnant. A cold pressed compact of silicon boride, aluminum boride, boron, and (aluminum boride-boron) were each positioned between powdered aluminum in a vacuum furnace which enabled the molten aluminum to infiltrate into the porous ceramic by capillary action. In addition, a porous ceramic compact of aluminum boride was similarly infiltrated with silicon.

Description

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment us use of any royalty thereon.

BACKGROUND OF THE INVENTION

This invention relates to the production of ceramic-metal materials, and more particularly to production by the infiltration of a porous cold pressed ceramic compact with a molten metal.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide and disclose the fabrication of ceramic-metal materials comprising the filtration of a molten metal into a porous ceramic compact.

It is a further object of the invention to provide and disclose a ceramic-metal material comprising a uniform dispersion of the metal in the ceramic.

It is a further object of the invention to provide and disclose a ceramic-metal material having each component in a continuous phase.

It is a further object of the present invention to provide and disclose a ceramic-metal material exhibiting ductility.

It is a further object of the present invention to provide and disclose a ceramic-metal material which is generally hard and non-ductile.

Other objects and a fuller understanding of the invention may be ascertained from the following description and claims taken in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a photomicrograph of a cross-sectional area microstructure of an AlB.sub.12 --Al infiltrated compact.

FIG. 2 is a photomicrograph of a cross-sectional area microstructure of an AlB.sub.12 --Si infiltrated compact.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Other objects and a fuller understanding of the invention may be ascertained from the following description and claims.

In an illustrative example, a cold pressed compact of AlB.sub.12 powder (minus 325 mesh), 1 inch in diameter and 0.3 inch thick, which was formed by applying 17,000 psi pressure to the powder in a cold pressing die, was utilized. A graphite crucible having an I.D. of 11/2 inch was lined with 0.005 inch thick grafoil sheet. Six grams of aluminum powder were placed at the bottom of the crucible and lightly tamped. The cold pressed AlB.sub.12 compact was placed on the aluminum powder. Six additional grams of aluminum powder were positioned on top of the AlB.sub.12 powder compact and a grafoil lid was placed over the top of the crucible. The crucible, loaded with AlB.sub.12 compact "sandwiched" between the aluminum powder, was placed in a vacuum furnace. The furnace was evacuated to approximately 10.sup..sup.-5 torr and the crucible was heated to 500.degree. C and held at this temperature 11/2 hours to permit outgassing. The temperature was subsequently raised to 1,100.degree. C and maintained for a period of 3 hours. At this temperature, the molten aluminum easily penetrated into the porous AlB.sub.2 compact.

The process was repeated utilizing silicon in lieu of the aluminum. The procedure was identical with the exception that the outgassing temperature was 750.degree. C for a period of 11/2 hours and the infiltration temperature was 1,500.degree. C for a period of 2 hours.

In addition to the above ceramic-metal materials, SiB.sub.6 --Al; B--Al; B.sub.4 C--Al/Si; and AlB.sub.12 --B-Al materials have been prepared utilizing the above conditions. The last material consisted of a ceramic skeleton comprised of 60% by weight AlB.sub.12 and 40% by weight boron, impregnated with aluminum metal. For B.sub.4 C--Al/Si, silicon was added to the aluminum and this combination was impregnated into B.sub.4 C, the silicon acting as a wetting agent.

TABLE ______________________________________ Density MOD. of ELASTIC SYSTEM (g/cc) RUPTURE MOD. ______________________________________ B-Al 2.32 17.500 psi 16.7.times.10.sup.6 AlB.sub.12 -Al 2.59 47.900 psi 32.3.times.10.sup.6 AlB.sub.12 -B-Al 2.47 30,000 psi 19.5.times.10.sup.6 ______________________________________

Densities of the ceramic-metal compositions were within the range of about 2.3 to about 2.7 g/cc. Possible uses of the ceramic-metal material include ceramic armor, ceramic composite bearings and wear-resistant specialized materials.

Although we have described out invention with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that numerous modifications may be resorted to in the ways of components and reaction conditions, etc. without departing from the spirit and scope of the invention.

Claims

Having described our invention, we claim:

1. A ceramic-metal composition consisting of a metal impregnated into a porous ceramic compact by infiltration, selected from the group consisting of:

2. A material in accordance with claim 1 wherein the ceramic-metal material is SiB.sub.6 --Al.

3. A material in accordance with claim 1 wherein the ceramic-metal material is AlB.sub.12 Si.

4. A material in accordance with claim 1 wherein the ceramic-metal material is B--Al.

5. A material in accordance with claim 1 wherein the ceramic-metal material is AlB.sub.12 --B-Al.

6. A ceramic-metal composition in accordance with claim 1 wherein the ceramic-metal composition is AlB.sub.12 --Al.