Emre TOY, BSc. Student
Metallurgy and Materials Engineering
Yıldız Technical University
Faculty of Chemistry - Metallurgy
Boron Carbide Synthesis via Aluminothermic Reaction
Boron carbide (B4C), crystalline compounds that various combinations of boron and carbon, is widely preferred in engineering applications thanks to its unique combination of properties which are extremely high hardness (38GPa Vickers Hardness), high elastic modulus (460GPa), high wear resistance, high melting point (2,763 °C), and low density (2.52 g/cm3). It has good shielding properties against neutrons and stability to most chemical and ionizing radiation.
Thanks to their properties, B4C can be used in tank armors, bulletproof applications, abrasive and wear resistance products, lightweight composites, and nuclear applications like control rods. The methods used in B4C synthesis are carbothermic reduction, metallothermic reduction, synthesis from elements, vapor phase reactions, synthesis from polymer precursors, liquid- phase reactions, ion beam synthesis, and VLS growth. However, the synthesis of this material is an expensive process because it requires high energy and temperature (keeps at 2000 o C to increase the rate of total reaction in carbothermic reduction). In our study, we are investigating to synthesize B4C at lower temperatures (1300-1650°C) via aluminothermic reduction, which is one of the metallothermic reduction reactions, in order to reduce the high energy, temperature, and cost requirement. The starting materials are boric acid (H3BO3), boron oxide (B2O3), graphite as carbon source, and aluminum powder which are assumed as pure. Six different composition mixtures are prepared under 3 main headings and they are stoichiometric, under- stoichiometric, and over-stoichiometric. All mixtures are milled and mechanically activated in a planetary ball mill machine for 1 hour. B4C is synthesized at 1300-1650 °C for 5 h under argon gas from prepared powder mixtures.