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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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The development of composites in the United States in the 1960s and 1970s is briefly reviewed with emphasis on aerospace applications. Consideration is given to such highlights as the manufacture of boron filaments, the use of boron-epoxy composites for aerospace structures, graphite-epoxy composites, and current graphite R & D work.
Room temperature mechanical behavior of various chemical and experimental graphites
Development of general constitutive equation for room temperature mechanical response of nuclear grade graphite
Orientation of crystallites in molded artificial graphites
X ray diffraction method to determine degree of orientation of crystallites in extruded graphites
Orientation and distribution of crystallites in molded artificial graphite
Catalytic effect of impurities on oxidation rate for selected artificial graphites
Nozzle material performance data were obtained, and the feasibility was determined of using new materials on the Scout rocket motor nozzles. Stress and heat transfer analyses were conducted to aid in the selection of optimum materials for nozzle tests. A reimpregnated and graphitized throat insert was fabricated along with two nozzles with ablative throats. The dissection and determining of char and erosion of two nozzles fired on X-259 loaded cases are discussed; one of the nozzles used a graphite phenolic ablative throat insert, and the other unit was a standard X-259 nozzle with a reduced area ATJ graphite throat insert.
Four clasts in three ordinary-chondrite regolith breccias are discovered which are a new kind of type 3 chondrite. As with ordinary and carbonaceous type 3 chondrites, they have distinct chondrules, some of which contain glass, highly heterogeneous olivines and pyroxenes, and predominantly monoclinic low-Ca pyroxenes. Instead of the usual, fine-grained, Fe-rich silicate matrix, however, the clasts have a matrix composed largely of aggregates of micron- and submicron-sized graphite and magnetite. The bulk compositions of the clasts, as well as the types of chondrules (largely porphyritic), are characteristic of type 3 ordinary chondrites, although chondrules in the clasts are somewhat smaller (0.1-0.5 mm). A close relationship with ordinary chondrites is also suggested by the presence of similar graphite-magnetite aggregates in seven type 3 ordinary chondrites. It is thought that this new kind of chondrite is probably the source of the abundant graphite-magnetite inclusions in ordinary-chondrite regolith breccias and that it may be more common than indicated by the absence of whole meteorites made of chondrules and graphite-magnetite.
The results of low velocity impact tests conducted on a graphite-polyimide laminate are presented. The 48-ply orthotropic laminate tested during this investigation is typical of laminates being proposed for heavily loaded aircraft wing skins. The nature of the damage is described as well as the effect of that damage on the compression strength of the 48-ply orthotropic laminate. The results obtained for the graphite-polyimide laminate are compared to existing results of similar tests conducted on other graphite-epoxy laminates.
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The microstructure and some microstructural effects of oxidation have been investigated for laminar carbon fiber cloth/cloth binder matrix composite materials. It was found that cloth wave is important in determining the macrostructure of the composites X-ray diffraction analysis showed that the composites were more graphitic than the constituent fiber phases, indicating a graphitic binder matrix phase. Various tests which were conducted to investigate specific properties of the material are described. It was learned that under the moderate temperature and oxidant flow conditions studied, C-700, 730 materials exhibit superior oxidation resistance primarily because of the inhibiting influence of the graphitized binder matrix.
Autoclave processing studies were conducted, using improved tack PMR-15 prepreg, to determine the effect of tack enhancing PMR resin modifications on composite processability and mechanical properties. Improved tack graphite fiber reinforced PMR-15 prepregs were prepared and exposed to ambient conditions for various times and then autoclave molded into composites. Composite specimens were prepared and tested for flexural and interlaminar shear strengths at room temperature and 316 C. The retention of flexural and interlaminar shear strength as a function of exposure in air at 316 C was also determined. The results show that the modified PMR resin solutions provide prepreg with improved tack and drape retention characteristics without adversely affecting processability or mechanical properties of autoclave molded graphite fiber reinforced PMR-15 composites.
Isotropic or anisotropic graphite is synthesized with precise control of particle size, distribution, and shape. The isotropic graphites are nearly perfectly isotropic, with thermal expansion coefficients two or three times those of ordinary graphites. The anisotropic graphites approach the anisotropy of pyrolytic graphite.
The following carbon-based materials are reviewed and their applications discussed: fullerenes; graphite (synthetic and manufactured); activated carbon fibers; and carbon-carbon composites. Carbon R&D activities at ORNL are emphasized.
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The graphite-magnetite component has been found (1) as abundant isolated inclusions in eight ordinary-chondritic, regolith breccias; (2) as the sole matrix in a new kind of unequilibrated chondrite that forms clasts in these regolith breccias; and (3) together with a Huss matrix in six unequilibrated ordinary chondrites. It is suggested that the component was formed by low-temperature, gas-solid reactions before the accretion of the meteorite, and that the isolated inclusions of graphite-magnetite in regolith breccias were derived from bodies composed of the new kind of chondrite that has graphite-magnetite as its sole matrix.
Investigation part of continuing effort to produce fibers strong enough to replace graphite in fiber/polymer composites.