Nanocomposites and nanomaterials

Formation of multicomponent gradient protective coatings on the basis multimetal system and carbon
Kosminska Yu.O., Perekrestov V.I., Gannych Yu.V.
Department of Nanoelectronics, Sumy State University, R.–Korsakova str. 2, Sumy 40007, Ukraine.
E-mail: y.kosminska@phe.sumdu.edu.ua

The aim of the present work is to develop ion–plasma technique for fabrication of multicomponent multilayered coatings with enhanced protective properties for potential application in nuclear power engineering. The main concern is in global problem of finding the Accident Tolerant Fuel, and multicomponent multilayered coatings can be used to coat fuel elements as an alternative solution [1, 2].
The proposed technique is based on patented dc magnetron sputterers combined with a hollow cathode. The sputtering target is composed of single-element constituent parts of cylindrical or plate-like shape. Elemental composition can easily be varied by adjusting the geometry of the target. The coatings can be deposited onto inner surface of low diameter pipes or flat surfaces. The external pipe or substrate holder can move along the sputtering target to allow depositing coatings with gradient change of elemental composition with depth.
In the present work (CrAlHfMoTaTiW)С and (СrНfTiTaWZr)C coating were deposited and there structure, phase composition, elemental distribution, surface morphology and microhardness were studied. It has been found that the coatings possessed finely dispersed structure with the grain size of about 10 nm, and the elemental distribution changed from Cr for underneath layers to НfTiTaWZr–C for upper layers. Correspondingly, structure changed from Cr bcc lattice to fcc lattice of carbide of metals mixture. Cr-including underlayers sufficiently increase the adhesion. Measured microhardness was up to 28 GPa. Assuming known information on radiation resistance and found properties of the coatings, one can predict their application as structural material for nuclear power engineering.

1.	Bischoff J., Delafoy C., Vauglin C. et al., AREVA NP’s enhanced accident-tolerant fuel developments: Focus on Cr-coated M5 cladding // Nucl. Eng. Technol.-2018.-50.-P.223-228.
2.	Pogrebnjak A. D., Yakushchenko I. V., Bondar O. V. et al. Irradiation resistance, microstructure and mechanical properties of nanostructured (TiZrHfVNbTa)N coatings // J. Alloy Compd.-2016.-679.-P.255-263.