US 5,330,849 A · Composite materials and methods for making the same

Abstract

The present invention generally relates to mechanisms for preventing undesirable oxidation (i.e., oxidation protection mechanisms) of reinforcement materials in composite bodies. The oxidation protection mechanisms include getterer materials which are added to the composite body which gather or scavenge undesirable oxidants which may enter the composite body. The getterer materials may be placed into at least a portion of the matrix such that any desirable oxidant approaching, for example, a fiber reinforcement, would be scavenged by (e.g., reacted with) the getterer. Ceramic filler materials which serve as reinforcements may have a plurality of super-imposed coatings thereon, at least one of which coatings may function as a getterer. The coated materials may be useful as reinforcing materials in ceramic matrix composites to provide improved mechanical properties such as fracture toughness. The present invention also relates to improved composites which incorporate these materials, and to their methods of manufacture.

Claims21

Dependent claims

A coated ceramic filler material adapted for use as a reinforcing component in a composite comprising a ceramic matrix embedding said filler material, said coated ceramic filler material comprising a ceramic filler material having a plurality of superimposed coating assemblies, said plurality comprising an interior assembly at least one assembly exterior to said interior assembly, each of said assemblies comprising a first coating and at least one coating exterior to said first coating and in substantially continuous contact with said first coating;

a boundary between said ceramic filler material and said coating in contact with said filler material forming a first zonal junction, the boundary between said ceramic matrix and said coating in contact with said ceramic matrix forming a second zonal junction, and each of the boundaries between adjacent coatings forming additional zonal junctions;
and the zonal shear strength of at least one of the zonal junctions being weak relative to a remainder of the other zonal junctions to permit (1) debonding of said filler material on application of stress prior to fracture of said filler material and (2) pull-out of said filler material upon fracture of said filler material.

A method for producing a self-supporting ceramic composite comprising a ceramic matrix embedding a coated filler material, said method comprising:

providing a permeable mass comprising at least one filler material;
providing a first coating in substantially continuous contact with said at least one filler material;
providing at least one additional coating in substantially continuous contact with said first coating on said ceramic material to form a multiply coated filler material comprising a plurality of coatings terminating at an exterior coating, the boundaries between each of said filler material, said coatings and said ceramic matrix thereby forming at least three zonal junctions, and the zonal shear strength of one of said three zonal junctions is weak relative to the other zonal junctions, and said exterior coating at least partially protecting from chemical degradation said filler and said first coating;
positioning a parent metal adjacent to said permeable mass comprising said multiply coated filler material and orienting said parent metal and said permeable mass relative to each other so that formation of an oxidation reaction product will occur in a direction towards and into said permeable mass of multiply coated filler material;
heating said parent metal to a temperature above its melting point but below the melting point of its oxidation reaction product to form a body of molten parent metal, and reacting said body of molten parent metal with an oxidant at said temperature to form said oxidation reaction product, and at said temperature maintaining at least a portion of said oxidation reaction product in contact with and extending between said body of molten parent metal and said oxidant, to draw said molten parent metal through said oxidation reaction product towards said oxidant and towards and into the adjacent permeable mass so that fresh oxidation reaction product continues to form within said mass of multiply coated filler material at an interface between said oxidant and previously formed oxidation reaction product;
and
continuing said reacting for a time sufficient to embed at least a portion of said multiply coated filler material within said oxidation reaction product.

4 more elements

Dependencies are inferred from the claim text.

Composite materials and methods for making the same

Life of this patent

Composite materials and methods for making the same

Life of this patent

Abstract

Claims21