Laser densification of glass ceramic coatings on carbon-carbon composite materials
AssigneeAmerican Research Corporation of Virginia
InventorsUsha Varshney, Howard P. Groger, Jesse J. Brown, Jr.
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Abstract
Alumino-silicate glass-ceramic coated carbon-carbon composite and graphitic substrates having resistance to oxidation and thermal cycling. The coatings are fabricated from plasma-sprayed powders of beta-spodumene, cordierite, beta-eucryptite or beta-quartz and are rapidly recrystallized by laser processing.
Claims18
A method for fabricating a glass-ceramic coated carbon-carbon or graphitic substrate material comprising the steps of:
- a. plasma-spraying a beta-quartz, beta-spodumene, cordierite or beta-eucryptite powder to form an amorphous film having a thickness of up to about 1000 microns on the surface of said substrate;
- and
- b. recrystallizing said amorphous film by scanning with a laser beam at a laser power density in the range of from about 100 to about 3000 W/cm.sup.2 and a laser scan rate in the range of from about 0.05 to about 7.5 cm/second.
A method for protecting a carbon-carbon composite or graphitic substrate material against oxidation and high temperature thermal cycling up to 1725 K., comprising forming an alumino-silicate glass-ceramic coating on said substrate by the following steps:
- a. roughening an outer surface of said substrate to a roughness in a range of from about 12.4 to about 25.4 microns root mean square;
- b. plasma-spraying at a pressure of about 760 Torr a beta-spodumene powder having a size in a range of from about 44 to about 120 microns to form an amorphous film having a thickness up to about 1000 microns on said outer surface of said substrate;
- and
- c. recrystallizing said amorphous film by scanning with a laser beam at a laser power density in the range of from about 400 to about 2000 W/cm.sup.2 and a laser scan rate in the range of from about 0.25 to about 5.10 cm/sec.
A method for protecting a carbon-carbon composite or graphitic substrate material against oxidation and high temperature thermal cycling up to 1725 K., comprising forming an alumino-silicate glass-ceramic coating on said substrate by the following steps:
- a. roughening an outer surface of said substrate to a roughness in the range of from about 12.4 to about 25.4 microns root mean square;
- b. plasma-spraying at a pressure of about 760 Torr a cordierite powder having a size in a range of from about -200 to about +325 mesh (44 to 120 microns) to form an amorphous film having a thickness in the range of up to 1000 microns on the surface of said substrate;
- and
- c. recrystallizing said amorphous film by scanning with a laser beam at a laser power density in the range of from about 400 to about 2000 W/cm.sup.2 and a laser scan rate in the range of from about 0.25 to about 5.10 cm/sec.
A method for protecting a carbon-carbon composite or graphitic substrate material against oxidation and high temperature thermal cycling up to 1725 K., comprising forming an alumino-silicate glass-ceramic coating on said substrate by the following steps:
- a. roughening an outer surface of said substrate to a roughness in the range of from about 12.4 to about 25.4 microns root mean square;
- b. plasma-spraying at a pressure of about 200 Torr a cordierite powder having a size in the range of from about -200 to about +325 mesh (44 to 120 microns) to form an amorphous film having a thickness in the range up to about 1000 microns on said outer surface of said substrate;
- and
- c. recrystallizing said amorphous film by scanning with a laser beam at a laser power density in the range of from about 350 to about 1300 W/cm.sup.2 and a laser scan rate in the range of from about 0.25 to about 1.27 cm/sec.
Dependencies are inferred from the claim text.