SESSION: AdvancedMaterialsTuePM3-R8 |
8th Intl Symposium on New & Advanced Materials and Technologies for Energy, Environment, Health and Sustainable Development |
Tue. 22 Oct. 2024 / Room: Ariadni B | |
Session Chairs: Tetiana Prikhna; Amr Henni; Student Monitors: TBA |
Ultra-high temperature (UHTC) transition metal borides can be used for a wide range of mechanical applications - as components of military and commercial equipment operating in extreme conditions, for rocket propulsion, hypersonic flights, atmospheric reentry, protective coatings on graphite, for using in abrasive, erosive, corrosive and high-temperature environments, which requires materials with significantly improved physical properties. To UHTC belongs TaB2 which exhibits high melting point (3200 °C), hardness (24.5 GPa -25.6 GPa), fracture toughness (4.5 MPa m0.5), bending strength (555 MPa), excellent chemical stability, electrical (308×104 Ω-1×m-1) and thermal (0.160 -0.161 W×cm-1×K-1 at 300-1300 oC) conductivity, good corrosion resistance [1-5]. To increase the oxidation resistance and mechanical characteristics TaB2 can be modified by silicides [1]. In the present study we investigated modification of TaB2 by MoSi2, ZrSi2 and Si3N4 in the amount of 20-30 wt.% and its sintering process under hot pressing conditions (30 MPa, 1750-1950 oC) and high pressure (4.1 GPa) - high temperature (1800 oC) conditions. The highest Vickers hardness HV=31.5 GPa and fracture toughness K1C=6 MPa×m0.5 under P= 9.8 N load was obtained for the composite sintered at 30 MPа, 1750 °C, 20 min from TaB2+20 wt.% ZrSi2, the increase of amount of ZrSi2 up to 30 wt.% leads to further increase in K1C= 6.9 MPa×m0.5, but to the reduction of microhardness down to HV=23.5 GPa. The composite sintered under 30 GPa at 1950 °C for 40 min from TaB2+20 wt.% MoSi2 showed HV=28.2 GPa and K1C= 5.42 MPa×m0.5. TaB2+30 wt.% Si3N4 sintered at 4.1 GPa, 1800 oC for 7 min had HV=18.8 GPa and K1C= 4.82 MPa×m0.5. The specific weight of the materials prepared from TaB2+20 wt.% MoSi2 was g=10.82 g/cm3, TaB2+30 wt.% Si3N4 - g=8.77 g/cm3, TaB2+20 wt.% ZrSi2 - g=9.35 g/cm3, TaB2+30 wt.% ZrSi2 - g=10.12 g/cm3.
AcknowledgementS: This work was supported by the Project of the National Academy of Sciences of Ukraine III-5-23 (0786) “Study of regularities and optimization of sintering parameters of composite materials based on refractory borides and carbides, their physical and mechanical properties in order to obtain products of complex shape for high-temperature equipment with an operating temperature of up to 2000 oC”