Simultaneous Synthesis and Densification of Carbon Nano-Materials Dispersed Boron Carbide Composites Using Pulsed Electric-Current Pressure Sintering (PECPS)

摘要

Dense [boron carbide (B_4C)]/[carbon nano-materials] composites were synthesized and sintered simultaneously using pulsed electric-current pressure sintering (PECPS) at 2173 K for 6.0× 10~2 s (10 min) under 50 MPa in a vacuum. The starting powders were amorphous B and C nano-powders and nano-carbons. The latter were acid-treated carbon nanofiber CNF and carbon nanotube CNT. The sintered composites were evaluated from the viewpoints of mechanical properties at high temperatures up to ～ 2023 K in inert atmosphere. Thus fabricated composites with 10vol%CNF maintained high bending strength σ_b around 750 MPa even at 1973 K; this temperature is 100 K higher than that of conventional B_4C/CNF composites, and furthermore 600 MPa at 2023 K. These high σ_b at elevated temperatures might be explained by both the low content of catalytic Fe particles and the rough surface of CNF after the acid-treatment. On the other hand, B_4C/CNT composites displayed 770 MPa at 1723 K. The stress-strain curves demonstrate that B_4C/CNF composite deformed elastically until 1273 K and plastically up to 1973 K, however, the B_4C/CNT composites displayed elastic deformation up to around 1873 K.