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Information × Registration Number 0219U102172, 0115U001458 , R & D reports Title Consolidation of nanostructured ceramics and nanocomposites with grains size below 50 nm and study of scale effect on their properties popup.stage_title Head Ragulya Andrii V., Доктор технічних наук Registration Date 20-12-2019 Organization Institute for Problems in Materials Science popup.description2 Mixtures of B4C, -AlB12 and B powders were reactively spark plasma sintered at 1800 °C. When the ratio R = B4C/ -AlB12 > 1.3 for a constant B-amount, the major phase in the samples is the orthorhombic AlB24C4, and when R < 1 the amount of AlB24C4 significantly decreases. A methodology of reactive SPS of unique BaCb-(BxOy/BN) composite with a nanolamellar BxOy/BN 3D-grain boundary framework is developed. The 3D-grain boundary framework BxOy/BN is the result of reactions of N2 with the initial boron carbide powder (B4C covered by B2O3 grains). The hardness of the hexagonal BN (h-BN) in the grain boundary framework is high and suggest that the turbostatic h-BN has formed. The possibility of controlling the dynamic mechanical properties as tested by Split Hopkinson Pressure Bar (SHPSB) method by optimization of the reactive SPS conditions is attempted. A significant five times improvement of the dynamic strength of massive boron carbide ceramics from ~6 to ~30 MJ/m2 and of the cracking strength from 2.2-4.0 to 5.0-7.5 MPa/m1/2 was obtained. A comprehensive study of nanocomposites based on Si3N4 - TiN obtained by method RCS was carried out. The materials strengthened by Si3N4 fibers with the grain size less than 150 nm, showed that these nanocomposites exhibit high mechanical properties and a significant decrease in the friction coefficient (<0.25) and specific wear (less than 5?10-8 mm3/N·m) in pairs with hard alloy and similar nanoceramics It was found that increasing the temperature production of HfH2 to 900 °C leads to growth concentration of hydrogen content to 0.84 wt.% іn the synthesized hydride. This enables the synthesis of HfN-HfB2 composition under reaction SPS at 1800 °C. Product Description popup.authors Ivanchenko Sergey E. Bаrаnovskyi Dmytro I. Borodianska Hanna Yuю Zamula Maryna V. Zhаlаt-Lozynskyi Ostаp B. Kolesnichenko Valery H. Petukhov Oleksandr S. Tyshchenko Nadezhda I. popup.nrat_date 2020-04-02 Close