Nanostructured surfaces

The effect of surface fractality on the functional properties of heteroxide composite coatings
M.V. Ved’, M.D. Sakhnenko, A.V. Karakurkchi, Y.Yu. Yermolenko
National Technical University “Kharkiv Polytechnic Institute”, Kyrpychova Str. 2, Kharkiv-61002, Ukraine.
E-mail: anyutikukr@gmail.com

The current direction of nanotechnology in the development of micro- and nano-electromechanical systems requires new parameters to characterize the geometry and surface properties. Atomic force microscopy (AFM) allows to study not only the geometry of the surface, but also many physical properties of the surface, including friction and microhardness at the nanoscale [1].
The effect of coatings electrosynthesis parameters on the fractal dimension of the surface, as well as the relationship of fractality with the functional properties of composites (microhardness, corrosion resistance, catalytic activity, and magnetic characteristics) was studied. Methods of AFM data analysis, microhardness measurements, the corrosion resistance, catalytic activity and magnetic characteristics investigation were used for characterisation composite coatings based on Al oxide matrics Al/Al2O3, Al/Al2O3·MnOx, Al/Al2O3·CoOy [2], as well as based on iron-cobalt alloy matrix Fe-Co-MOx (where M – Mo, W). 
It is established that the fractal dimension is not a random variable, but perfectly reflects both the features of the surface topography and the fundamental properties of thin-film coatings, which are determined by their deposition technique. The fractal dimension can be used as a diagnostic parameter characterizing the structure and mechanical properties of the surface layer. The corrosion resistance, tribological and elastic properties of the surface correlate with the value of the fractal dimension: in areas with a high fractal dimension, friction as well as corrosion rate are maximal, and the elasticity of the material is minimal. An increase in the fractal dimension of the surface makes it possible to increase the catalytic activity and sensitivity of sensors based on thin-film composite materials.

1.	Yar-Mukhamedova G.Sh., Sakhnenko N.D., Ved' M.V. and etc. Surface analysis of Fe-Co-Mo electrolytic coatings // IOP Conf. Ser.: Mater. Sci. & Engin. .-2017.-213.- 012019.
2.	Karakurkchi A., Sakhnenko N., Ved’ M. and etc. Application of oxide-metallic catalysts on valve metals for ecological catalysis // East.-Europ. J Enterpr. Technol.-2017.-5/10 (89).-P. 12-18.