Electrical and mechanical properties of composites ti–carbon nanotubes

Abstract

The mechanical and electrical properties of Ti–CNT powder nanosystems obtained by mechanical mixing are studied depending on the concentration of multilayered carbon nanotubes (CNTs) and the degree of compression of the investigated samples. As shown an analysis of these properties, their qualita-tive and quantitative changes in the concentration range of 1.5–33% wt. CNTs are determined. These changes indicate the formation of composites. Thus, the electrical conductivity of composites differs significantly both from the corresponding values for the initial components and from the average values expected for a classical mixture. This effect is determined by a transfer of free electrons from the metal to the CNTs, by a comparable number of electrical contacts between the composite’s components of different (metal–CNT) and the same (mainly CNT–CNTs) nature, and competition between the numbers of tunnelling and ohmic contacts. As shown, the pre-treatment with compression makes it possible to increase the maximum value of the electrical conductivity of the composite by a factor of ≅1.5 due to adhe-sion at high pressures of CNTs and metal particles. This leads after subsequent milling and loading of the powder material to a decrease in amount of direct contacts between metal particles and to an increase in number of contacts between CNTs with an increased concentration of free charge carriers. Such nanostructured materials are promising for creating electrodes for ‘cold’ photothermoelectrical energy converters.