RESEARCH AND DEVELOPMENT ON ADVANCED GRAPHITE MATERIALS. VOLUME XIII. DEVELOPMENT OF A FINE-GRAIN ISOTROPIC GRAPHITE FOR STRUCTURAL AND SUBSTRATE APPLICATIONS.
Rept. for May 60-Sep 62
NATIONAL CARBON CO LAWRENCEBURG TENN
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The report describes the development, fabrication, and physical properties of grade RVC graphite formerly designated as experimental grade RT-0029. Grade RVC was manufactured in sizes up to 18 inches in diameter by 15 inches in length and is nominally characterized by a bulk density of 1.81 gcc, an admittance to N sub 2 of .02 and .006 sq. cm. sec. w. g. and a. g. respectively, and a room temperature flexural strength w.g. and a.g. of 2560 and 1930 lbs sq. in. respectively. RVC is an excellent substrate material for silicon carbide coatings because its thermal expansion between 400 and 1000C is approximately 0.3 per cent in both grain directions. This expansion is in the same range as that for silicon carbide. Results are also presented on high temperature oxidation of silicon carbide coated grade RVC specimens. The unusually good oxidation protection afforded the graphite by the coating demonstrates the marked superiority of this substrate over other graphite materials which do not match the silicon carbide in thermal expansion. Author