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The article presents the synthesis of multi-walled carbon nanotubes (MWCNTs) on the porous nickel foam (3D-Ni) surface using the chemical vapor deposition (CVD) method, followed by the field emission characteristics of the resulting 3D-Ni/MWCNT nanocomposite structures. The characterization of the 3D-Ni/MWCNT morphology showed a uniform distribution of the "moss-like" CNT coating on the walls of the porous 3D-Ni. TEM images showed a high number of walls in MWCNTs, which made such a material resistant to destruction under conditions of strong electric fields during the field emission process. The studies also showed a high degree of chemical purity of the synthesized MWCNTs under the presented technological conditions. An increase in the emission current due to the introduction of CNTs into the structure of porous 3D-Ni is shown. 3D-Ni/MWCNTs field emitter showed a low turn-on field of 5.41 V/μm; a field enhancement factor of 915; and high operating stability. For the first time, the current mode of 3D-Ni-MWCNTs cathode was tested for compliance with the classical field emission law using the Forbes "orthodoxy" test. [ABSTRACT FROM AUTHOR]

The present article considers a comparative analysis of two elastomers, polyurethane (PUС) and organosilicon (OSC), both modified with 1.0–9.0 wt.% multiwall carbon nanotubes (MWCNTs). The MWCNTs‐1 and MWCNTs‐2 were synthesized through CVD method using Co‐Mo/Al2O3‐MgO and Fe‐Co/2,1Al2O3. The results obtained showed that the lowest bulk conductivity (5 × 10−10 S × cm−1) was typical for PUC elastomer modified with 1 wt.% MWCNTs‐2. As for OSC elastomer (modified with 9 wt.% MWCNTs‐1), the lowest bulk conductivity was found to be 0.4 S × cm−1. The maximum temperature field uniformity was established for OSC elastomer modified with 7 wt.% MWCNTs‐2, whereas in the modified PUC‐based elastomer, the nonuniform temperature field took place. This might be caused by local MWCNTs entanglement manifested in the formation of agglomerates or a denser packing of conductive networks. The best combination of the polymer matrix and MWCNTs type was revealed. Finally, it was established that for electric heaters, it is the most efficient to employ OSC modified with 7 wt.% MWCNTs and use MWCNTs‐1 or MWCNTs‐2, depending on the feeding voltage level of 12 or 24 V. This study is of special importance in household purposes, clothing with built‐in heating panels, car/tractor systems, minibus interiors, onboard thermal ventilation systems, clothing, and aircraft industries. [ABSTRACT FROM AUTHOR]

The article deals with research related to the issues of nanomodification of elastomers as a basis of electric heaters with self-regulating temperature. The effect of multistage mechanical activation of multilayer carbon nanotubes (MCNTs) with graphite on the uniformity of the temperature field distribution on the surface of nanomodified organosilicon elastomer has been studied. The influence of the stages of mechanical action on the parameters of MCNTs is revealed. It has been ascertained that for the MCNTs/graphite bulk material, which has passed the stage of mechanical activation in the vortex layer apparatus, a more uniform distribution of the temperature field and an increase in temperature to 57.1 °C at the supply voltage of 100 V are typical. The distribution of the temperature field in the centrifugal paddle mixer "WF-20B" for mixing MCNTs with graphite has been investigated. It has been found that there is also a thermal effect in addition to the mechanical action on the MCNTs in the paddle mixer "WF-20B". The thermal effect is associated with the transfer of the mechanical energy of friction of the binary mixture MCNTs/graphite on the paddle and the walls of the vessel. The multiplicity of the starting current Ip to the nominal In (Ip/In) is 5 for the first sample, 7.5 for the second sample, and 10 for the third sample at the supply voltage of 100 V. The effect of reducing the starting current and stabilizing the temperature indicates the presence of self-regulation, which is expressed in maintaining a certain level of temperature. [ABSTRACT FROM AUTHOR]