Aspects of the directional synthesis of carbon nanotubes to create hierarchical radio-absorbing composite materials

Abstract

The conducted information review showed that there are various types of radio absorbing materials. The expansion of the working wavelength range for radio-absorbing composites is possible due to the combined use of conductive fillers, characterized by different magnetic and dielectric characteristics and the value of electrical conductivity. As a rule, the increase in the efficiency of radio absorption of materials is associated with an increase in the concentration of metal fillers in them, as a result of which the weight and size parameters increase proportionally. To avoid this, the use of carbon nanomaterials, which have the ability to create self-organizing hierarchical structures in the bulk of the composite, allows. Varying the composition of the catalytic systems of the CVD process allows directional synthesis of carbon nanomaterials with the necessary morphological characteristics. To assess the effect of the composition of the catalyst on the morphology and structure of the synthesized CNTs, 3 Ni / MgO catalyst compositions with different contents of the active component (Ni) were selected. The effectiveness of the obtained catalysts was determined by the specific yield of CNTs (gC/gkat). The morphology and structure of the catalysts and the synthesized CNTs were studied by means of scanning electron microscopy (a Hitachi H-800 transmission electron microscope). CNTs were additionally examined by transmission electron microscopy (a Hitachi H-800 transmission electron microscope). The use of a nickel-based catalyst provides the material with magnetic properties. The diameter of carbon filiform formations synthesized on Ni/0.16MgO and Ni / 0.3MgO catalysts is ~ 30 ? 60 nm. The Ni/0.5MgO system is characterized by low productivity in one-dimensional nanostructures; the sample after the CVD process contains a large number of unstructured forms of carbon and an unchanged catalyst. Structural diversity in carbon nanomaterials allows to obtain on their basis an effective hierarchical structure in the radio absorbing composite..