| Popis: |
Boron carbide is widely used materials for its attractive combination of properties such as high hardness, low density, high melting point, excellent thermoelectric properties, etc. As well, sintered boron carbide is commonly used, also its powder is applicable for many areas of industry. The aim of study was produce nanopowders and dense bodies of B 4 C via Spark Plasma Sintering (SPS). Fast and effective SPS method gives opportunity to preserve nanocrystalline structure of obtained samples. Nanopowder produces via SPS method were compared with powder synthesized due to carbothermal reaction. Amorphouse boron and carbone powders were used as precursors. Without additives nanopowders were produced with pressureless SPS regime at 5 min-1600°C. Diffraction peak profile analyses and SEM micrographs detects nanopowder with grain size less than 100nm. Additional advantage of proposed method contributes to formation of powder without extra carbon, which represent serious challenge of standard technology. Sintering process of bulk samples was conduct under 20MPa at 1700°C and holding time during 5–10min. Composition B 4 C - SiC ceramic aslo were produce with 30%–70% percentage distribution of compounds. For comparison of dense bodies standard boron carbide has been hot pressed during 2 h under 1900°C temperature. SPS densification of fully dense samples requires lower temperature and several minutes (1700°C–10min), instead of long-standing and high temperature procedures. |
