"Nanotechnology and nanomaterials"
Nanocomposite Material of the Si3N4–ZrN System for the Manufacture of Bearings with the Self-Healing Effect 

Zgalat-Lozynskyi О. B., Zyatkevych D. P., Eremenko L. І., Kud І. V., Krushynska L. А., Shyrokov О. V.
Frantsevich Institute for Problems of Materials Science NAS of Ukraine,
3, Krzhyzhanovsky St., Kiev, 03142, Ukraine. E-mail: dp12345@ukr.net
Silicon nitride ceramics is extensively used for the manufacture of bearings for operation under severe conditions of friction in corrosive-erosive media without lubrication under substantial loads. The introduction of zirconium nitride into the silicon nitride matrix makes it possible to enhance the corrosion resistance due to the formation of insoluble oxide layers. During contact in an aqueous medium, gel, which has a larger volume and protects grains and grain boundaries from further corrosion, forms [1].
The aim of the present work is to investigate the synthesis of Si3N4ZrN disperse composite powders in the process of nitriding of a precursor that is a product of interaction of zirconium and silicon nitride in vacuum and study the consolidation of powders and their properties.
The analysis of the experimental data enables us to draw the conclusion on the reasonability of using the highly active product of vacuum solid-state interaction of Zr and Si3N4 at a temperature of 1000°С. It serves as a precursor for obtaining the Si3N4–ZrN composite material in the process of subsequent nitriding. The possibility of obtaining the composite material in a wide concentration range from 10 up to 40 vol. % of zirconium was established.
Consolidation of synthesized powder mixtures silicon nitride – zirconium has been performed by Spark Plasma Sintering (SPS) in the temperature range from 1650 to 1750°С. Utilize the few step SPS process high degree of densification together with fine microstructure could be achieved for investigated ceramic composites via regulation of heating rate and level of pressure on the final stages of consolidation [2]. The effect of non-linear heating and loading regimes on consolidation of high melting point nanocomposites has been investigated to develop optimal regimes of consolidation. SPS consolidated Si3N4-ZrN composites demonstrate near fully dense and fine homogeneous microstructure. Moreover, the special graphite press-instrument and sintering schedules were developed to consolidate by SPS parts for ceramics ball bearings.

1.	Harrison R. W., Lee W. E. Processing and properties of ZrC, ZrN and ZrCN ceramics: a review // Adv Appl. Ceram.-2016.-115,- N 5.-P. 294-307.
2.	Zgalat-Lozynskyy O., Herrmann M., Ragulya A. Spark plasma sintering of TiCN nanopowders in non-linear heating and loading regimes J. Europ. Ceram. Soc.- 2011.- 31 .- P.809–813