Sintering of Nanoscaled Tungsten Powder Produced by electrical explosion process

Abstract

Nanoscaled tungsten powder was produced by Electrical Explosion of Wire (EEW) Process. The oxide passivation layer was removed from the produced powders by a reduction treatment. Prepared nanoscaled tungsten powders were sintered by pressureless sintering, spark-plasma sintering and shockwave compaction, respectively. Sintered property and microstructure were compared. The effect of oxygen content on the sintering behavior was confirmed showing a different sinterability. Sintered density of higher than 95% theoretical density could be obtained from the spark-plasma sintering even at 1500oC for the nanoscaled tungsten powder compact with controlled oxygen content, while the highest slntered density from the pressureless sintering at the same temperature was only 81 % TD. The activation energy for spark-plasma sintering was 95.85 kJmol-1 which was much smaller than the reported ones of pure micron-size tungsten powders between 380 and 460 kJmol-1 . In spite of the inhomogeneity in microstructure the explosive compaction seemed also effective for obtaining highdensity from nanoscaled tungsten powders with limited grain growth