#pdf on pyrolytic graphite or pyrolytic carbon #materials, giving in particular a resistivity of .5×10⁻³ Ω·cm, which I guess means that if you have a 10 cm × 1 cm × 1 cm block of it, the resistance is .5 × 10⁻3 Ω·cm · 10 cm / 1 cm / 1 cm = 5 mΩ of resistance, which is in the neighborhood of metal conductors. .5×10⁻³ Ω·cm would be 50μΩm.
amorphous carbon #materials resistivity #data: 15 to 46 μΩm, slightly more conductive than pyrolytic graphite, and also in the neighborhood of metal conductors.
apparently different vegetable #charcoal #materials have resistivities in the neighborhood of 10 to 20 mΩ·m, almost 1000 times higher than pyrolytic graphite or amorphous carbon, but still low enough to be practical as electrodes. #data
#paper saying that a packed bed of #charcoal (i.e. carbonized biomass) particles under 8 MPa of pressure can have reasonably low resistivity: they say “σ < 0.2 Ω·cm”, which I guess means 2 mΩm, which is pretty low but higher than pyrolytic carbon #materials. Also, it says heat-treating 1050° lowers the resistivity by five orders of magnitude.
#PDF #paper on properties of #charcoal #materials, finding reasonably high conductance (.76 and .5 Ω·cm for cypress charcoal, which I guess is 5 to 8 mΩm, pretty decent conductivity).
A popular presentation of the Lackner-Wendt proposal for the “auxon” #self-replicating machine; Klaus Lackner and Christopher Wendt, article by Thomas Bass, October 01, 1995.
The 1995 Lackner-Wendt “auxon” #paper on #self-replicating robots, “Exponential growth of large self-reproducing machine systems”. Particularly interesting: “Carbon plays a special role because it becomes gaseous when oxidized and, as a result, its reducing power increases steadily with temperature. It is moderate at low temperatures but at 2200°C carbon reduces all the other common elements.” If I understand the diagram correctly, the last one it crosses is CaO, crossing Al₂O₃ just a bit below, around 2000°. However, their proposed element separation cycle is a bit more complex than that would suggest. Does this really imply that you can smelt aluminum by heating alumina above 2200° inside charred bread? There are two footnotes about industrially-feasible carbothermic aluminum reduction, but unfortunately they’re in a 1988 conference proceedings. Fortunately, there is more recent research. #materials