Combustion synthesis and consolidation B4C–TiB2 composites

Abstract

The paper presents experimental results of preparation the B 4 C-TiB 2 composites by combining the self-propagating hightemperature synthesis (SHS) and pressing of hot product with use of an additional heat source (chemical oven). The adiabatic temperature and composition of equilibrium combustion product were calculated with use the program of thermodynamic calculations THERMO. It was shown during exothermic reaction are formed TiB 2 as disperse phase and B 4 C as ceramic binder. Adiabatic combustion temperature and quantity of liquid phase are depended from content of ceramic binder. The influence of reaction mixture composition and mass of chemical oven on the magnitude of the residual porosity had been studied. Found that minimal residual porosity (3 %) is achieved at 20-40 wt. % B 4 C content in end product and mass ratio of green sample and chemical oven 1 : 4. The influence of mixture composition on phase composition and microstructure of the ceramic composites has been studied. XRD analysis showed that during exothermic synthesis had been formed TiB 2 and B 4 C. It was established B 4 C content has a significant influence on microstructure formation of SHS-composites. At the B 4 C content less than 20 wt. % ceramic composite was formed with homogeneous microstructure and TiB 2 grain size of ~10 microns. Increasing of the B 4 C contents up to 50 wt. % reduces the size of TiB 2 particles down to 0.5 microns and results to formation of the ceramic composites with inhomogeneous microstructure. It is shown that the obtained ceramic composites possess high Vickers hardness (32.84-33.64 GPa).

Термодинамический Анализ Получения Свс-Композиционных Материалов На Основе Карбида Бора

“…Высокая цена чистого бора, используемого в качестве реагента, делает процесс экономически нецелесообразным. Зачастую получение данных материалов невозможно осуществить в рамках традиционных представлений о равновесных состояниях и требует привлечения новых подходов и методов синтеза специального класса композиционных керамических материалов [3][4][5][6].…”

“…Общая теxнологичеcкая cxема CВC -отличаетcя пpоcтотой аппаpатуpного офоpмления, быcтpотой пpоцеccа, малой энеpгоемкоcтью, экологической безопасность. Метод СВС дает широкие возможности использования магния или алюминия в качестве восстановителя при синтезе материалов горением условиях [6][7][8][9][10][11].…”

“…Blank VD (2017) Solid state physics [Fizika tverdogo tela] 59(2):318-321. DOI: 10.21883/ FTT.2017.02.44055.302 (in Russian) [6]. Shcherbakov VA, Gryadunov AN, Alymov MI, Sachkova NV (2016) Letters on materials.…”

“…Shcherbakov VA, Gryadunov AN, Alymov MI, Sachkova NV (2016) Letters on materials. 6(3):217-220. [7].…”