Microwave synthesis of B4C nanopowder for subsequent spark plasma sintering

Abstract

Utilization of microwave-assisted (MW) synthesis and subsequent spark plasma sintering as an efficient and rapid synthetic route toward the preparation and consolidation of ultrahard B4C boron carbide without additives is reported. Magnesium dodecaboride (MgB12) and carbon were used as raw materials for stepwise MW synthesis of B4C at irradiation power of 900 W. The comprehensive analytical studies showed that after few minutes of microwave irradiation of reactive mixture single phase nanoparticles of boron carbide (40–50 nm) covered by carbon nanolayer are formed. Optimum sintering parameters for the powder compaction were revealed and dense specimens (>99%) with hardness of around 35 GPa and substantially improved fracture toughness of 5.7 MPa m1/2 were produced from nanosized B4C powder without any additives. Erosive wear behaviour of B4C against silica particles impact studied at room temperature demonstrated a high erosion resistance for the fully dense compacts sintered at 1900 °C. Keywords: Boron carbide, Nanopowder, Microwave assisted synthesis, Spark plasma sintering