In-situ formation of reinforcement phases in ultra high temperature ceramic composites
AssigneeThe United States of America as Represented by the Administrator of the National Aeronautics & Space Administration (NASA)
InventorsMargaret M Stackpoole, Matthew J Gasch, Michael W Olson, Ian W. Hamby, Sylvia M Johnson
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Abstract
A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB2, ZrB2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.
Claims14
A method of forming a ceramic composite, the method comprising:
- mixing a pre-ceramic polymer and a solvent into a powder of an ultra-high-temperature ceramic (UHTC) material, and allowing the pre-ceramic polymer to coat grains of the UHTC material approximately uniformly, wherein the process of mixing comprises:
- (i) creating a slurry comprising the powder of the UHTC material, the pre-ceramic polymer and the solvent;
- (ii) producing droplets of the slurry;
- and
- (ii) removing or separating at least a portion of the solvent from the slurry,
- wherein said UHTC material is a boron-containing material, comprising at least one of HfB2 and ZrB2 and having a melting temperature of at least 2000° C.;
- thermally consolidating the mixture at a consolidation temperature of at least about 2000° C. for a thermal consolidation time interval in a range of about 30-180 minutes and at an applied pressure of at least 10 MPa;
- and
- allowing acicular reinforcement rods or fibers or whiskers to grow from the UHTC grains during thermal consolidation.
A method of forming a ceramic composite, the method comprising:
- mixing a pre-ceramic polymer and a solvent into a powder of an ultra-high-temperature ceramic (UHTC) material, and allowing the pre-ceramic polymer to coat grains of the UHTC material approximately uniformly, wherein the process of mixing comprises:
- (i) creating a slurry comprising the powder of the UHTC material, the pre-ceramic polymer and the solvent;
- (ii) producing droplets of the slurry;
- and
- (ii) removing or separating at least a portion of the solvent from the slurry;
- thermally consolidating the mixture at a consolidation temperature of at least about 1800° C. for a thermal consolidation time interval in a range of about 30-180 minutes and at an applied pressure of at least 10 MPa;
- and
- allowing acicular reinforcement rods or fibers or whiskers to grow from the UHTC grains during thermal consolidation, wherein at least one of the acicular reinforcement rods or fibers or whiskers has an aspect ratio of at least 10:1.
Dependencies are inferred from the claim text.