Thermal conductivity measures the heat flux given a temperature gradient. That is, how fast heat energy flows across a surface, given a certain temperature gradient across it.
It has nothing to do with the velocity of the heat carriers themselves (phonons, or charged particles).
E.g. phonons always travel at the speed of sound, in any material.
It has nothing to do with the velocity of the heat carriers themselves (phonons, or charged particles).
E.g. phonons always travel at the speed of sound, in any material.