Graphite rods, 305mm

Spectrographically pure graphite rods 305mm long. Both carbon and graphite rods contain amorphous and graphite carbon. Analytically these rods are identical - spectrographically pure carbon. The graphite content of carbon rods is increased by high temperature baking. Dull, dark-grey rods are high in carbon and shiny, silver-grey rods are high in graphite. Graphite rods have less electrical resistance; they are better electrical conductors, so under vacuum they need greater electric currents to sublime. The possible and actual evaporator settings determine which rods work better. For carbon coatings and films in electron microscopy most operators prefer graphite rods. Spectrographically pure carbon rods are now difficult to obtain and we can no longer supply these.

Carbon's melting and sublimation points: ~3550°C; boiling point is 4200°C; evaporation temp (at which a substance has a vapour pressure of 1.33 x 10-2 mbar): 2400°C.

These are Grade 1 rods; impurities are under 2ppm.

SDS