Electron Percolation In Copper Infiltrated Carbon

Abstract

The work describes the dependence of the electrical conductivity of carbon materials infiltrated with copper in a vacuumpressure autoclave on copper concentration and on the effective pore radius of the carbon skeleton. In comparison with noninfiltrated material the electrical conductivity of copper infiltrated composite increased almost 500 times. If the composite contained less than 7.2 vol% of Cu, a linear dependence of the electrical conductivity upon cupper content was observed. If infiltrated carbon contained more than 7.2 vol% of Cu, the dependence was nonlinear -the curve could be described by a power formula (x − xc) t . This is a typical formula describing the electron percolation process in regions containing higher Cu fraction than the critical one. The maximum measured electrical conductivity was 396 × 10 4 Ω −1 m −1 for copper concentration 27.6 vol%. Experiments and analysis of the electrical conductivity showed that electron percolation occurred in carbon materials infiltrated by copper when the copper volume exceeded the critical concentration. The analysis also showed a sharp increase of electrical conductivity in composites with copper concentration higher than the threshold, where the effective radius of carbon skeleton pores decreased to 350 nanometres.

Hygroexpansion and Surface Roughness Cause Defects and Increase the Electrical Resistivity of Physical Vapor Deposited Aluminum Coatings on Paper

“…Various models have been presented to describe phenomena as the effect of hygroexpansion and roughness, such as the model according to the Effective Medium Theory [36,37], Maxwell [38], Maxwell-Garnet [39], Hamilton [40], power law approximation [41], Taylor series [42], percolation models [43,44], bond site models [45,46], and others [20]. However, more data are needed to enable the rational selection and interpretation of such models, which would be desirable for further research.…”