Ramakrishna T Bhatt

20120076927, Mar 29, 2012

Feb 1, 2011

13/018611

Ramakrishna T. Bhatt - North Olmsted OH, US
James A. Dicarlo - North Olmsted OH, US

UNITED STATES GOVERNMENT AS REPRESENTED BY THE SECRETARY OF THE ARMY - WASHINGTON DC

B05D 5/12
C04B 35/64

427122, 264614

A thermal treatment process for improving thermo-mechanical properties of ceramic matrix composite materials such as silicon carbide (SiC) matrix composites is described. The treatment process removes excess silicon and/or other process-related defects from the SiC-based matrix as well as the fiber interfacial coating. This invention can be practiced with minimal strength loss for as-fabricated composites formed from high-strength continuous-length ceramic and carbon-based fibers that are functionally stable to 1600 C. and above. The invention provides a method for significantly improving composite thermal conductivity and creep resistance, and for reducing composite porosity. It has been demonstrated using state-of-the-art 2D woven SiC/SiC composites containing Sylramic-iBN SiC fibers, boron-nitride-based interfacial coatings, and hybrid matrices that are based on SIC formed by chemical vapor infiltration (CVI) and by a combination of CNI, SiC particulate infiltration, polymer infiltration and pyrolysis, and melt infiltration of silicon, silicon-based alloys, and silicides.

46891889, Aug 25, 1987

Jul 16, 1986

6/886149

Ramakrishna T. Bhatt - North Olmsted OH

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

C04B 3580

264 60

Alternate layers of mats of specially coated SiC fibers and silicon monotapes are hot pressed in two stages: In the first a die is heated to about 600. degree. C. in a vacuum furnace and maintained at this temperature for about one-half hour to remove fugitive binder. In the second stage the die temperature is raised to about 1000. degree. C. and the layers are pressed at between 35 MPa and 138 MPa. The resulting preform is placed in a rector tube where a nitriding gas is flowed past the preform at 1100. degree. C. to 1400. degree. C. to nitride the same.

47819936, Nov 1, 1988

Apr 15, 1987

7/038560

Ramakrishna T. Bhatt - North Olmsted OH

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

B32B 900
B32B 1900
C04B 3502

428698

A strong and tough SiC/RBSN composite material comprises silicon fibers and a reaction bonded silicon nitride matrix. This composite material may be used at elevated temperatures up to at least 1400. degree. C.