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The present work is dealing with the study of a nano-compositional material which was obtained on the basis of PTFE with 2.5÷10wt% of core-shell type Fe-doped carbon nano-tubes and carbon nano-particles as fillers. The PTFE samples without the fillers were prepared too. Weight wear, friction coefficient and temperature were measured after passing some velocity steps, and afterwards the linear wear was calculated. The obtained results have shown that the incorporation of about 2,5÷5wt% of Fe-doped CNTs into PTFE matrix drastically improves the antifrictional properties in comparison to the unfilled PTFE. Namely, the wear resistance of these nanocompositions increased by the factor of 500-150 in the range of friction velocities 0.25÷1.25 m/sec. Increase of the filler portion up to 10wt% transforms the obtained nanocomposite from antifrictional to friction material with the enhanced coefficient of friction up to 0.32, but with the unexpectedly ultra-low wear. SEM-EDX analyses of the worn surfaces of the tested nanocomposites and the cast iron samples after working as a tribological pair, revealed some favorable effects of the Fe-doped CNTs filler on the formation mechanism of a transfer film and its role in promoting very low wear of the obtained new nanocomposites.

The present work deals with the special experiments on SEM-EDX study of morphology, chemical composition and topological transformations of the initial ground surface of the bulk iron plate-substrate after its interaction with the ethanol vapor pyrolysis products at high temperatures in the closed-loop and open cycle reactors. Our experiments have shown that the mechanism of formation of Fe clusters-doped CNFs on plate-substrate surfaces may be represented as a process, the first stage of which is a protonation of the substrate subsurface layers caused by diffusion of hydrogen atoms facilitating the formation of 3D nano-groups of Fe atoms assembled in the characteristic clusters with magic numbers of atoms, depending on the thermodynamics of the metal. The spontaneous coalescence of these clusters into giant Feclusters at comparatively low temperatures and formation of iron nano-droplets at comparatively high temperatures results in the formation of a nanopatterned surface with the uniformly distributed catalytic centers of CNFs nucleation. The second stage of the process is a nanoparticle-guided growth through the VLS or VS (at low temperatures) growth mechanisms in which the one cluster provides a nucleation of only one CNF particle so that the sizes of the nucleation centers determine the basic size of the CNF nanoparticles.

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