University of California

United States of America As Represented by the Administrator of Nasa

Matthew J Gasch

Julin Wan

Amiya K Mukherjee

Sylvia M Johnson

Margaret M Stackpoole

Ian W Hamby

Michael W Olson

A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB, ZrBor 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.

In-situ formation of reinforcement phases in ultra high temperature ceramic composites

Densified composites of silicon nitride, silicon carbide, and boron nitride that exhibit high creep resistance are obtained by sintering a mixture of amorphous powders of silicon nitride, silicon carbide, and boron nitride in the presence of an electric field under high pressure. The grain size in the resulting composite is less than 100 nanometers for all components of the composite, and the composite exhibits high creep resistance.

Nanocomposites of silicon nitride, silicon carbide, and boron nitride

Densified composites of silicon nitride and silicon carbide that exhibit high creep resistance are obtained by mechanically activating a mixture of amorphous powders of silicon nitride and silicon carbide and sintering the mechanically activated mixture in the presence of an electric field under high pressure. The grain size in the resulting composite is less than 100 nanometers for all components of the composite, and the composite exhibits high creep resistance.

Method of forming silicon carbide and silicon nitride composite

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Matthew J Gasch