Abstract
Systematic morphological observations and surface analyses were completed in order to clarify the surface structure of “woodceramics”, i.e., carbon-carbon composite materials consisting of plant-originated carbon reinforced by carbon generated from phenol resin. The woodceramics manufactured from cedar sawdust at various temperatures (650°, 700°, 800°, 1000° and 1200°C) in a nitrogen atmosphere were examined. The microstructure was not affected by the manufacturing temperatures; bundles of the micro-tubes of the original plant (cedar) were preserved. The nanostructure was also unaffected by the manufacturing temperatures except for the one manufactured at the highest temperature (1200°C). Fine needles (fibers) on the surface of the 1000°C-prepared specimen were incorporated into the substrate for the 1200°C-prepared specimen. The oxygen/carbon atomic ratio (0.14) determined by XPS was approximately constant for all specimens manufactured at various temperatures. This value agreed with that of the bulk composition (0.12) except for the one (0.07) manufactured at the highest temperature (1200°C). The binding energy of C1s (284.1 eV) was attributed to elementary carbon. The binding energies of C1s and O1s (532.4 eV) were unchanged by the manufacturing at different temperatures. The specimens manufactured at low temperatures (650°, 700° and 750°C) showed high hydrogen/oxygen atomic ratios (2.6, 2.0 and 1.9, respectively) while those manufactured at high temperatures (1000° and 1200°C) had the lower values (1.3 and 1.4, respectively). The X-ray diffraction analysis indicated an amorphous phase with weak hallos at 23.7° and 43.1° (d-spacing; 0.375 and 0.210 nm, respectively). The weak peaks at 30.41°, 35.30° and 50.84° (d-spacings; 0.2937, 0.2541 and 0.1795 nm, respectively) that appeared eventually were attributed to a minute amount of impurities.
