Abstract
Fine WC powder obtained by a vapor phase reaction (f-WC, -0.07μ) and commercial WC powder (c-WC, -l μ) were sintered at 1100-1500°C in hydrogen and at 1500°C and 1800°C in vacuum with emphasis on the particle size-effect on their sinterabilities.
The sintering of both f-WC and c-WC powders began at about 1100°C. The densification of powder compacts proceeded rapidly in the early period and stopped substantially after 0.5 hr. This rapid densification seemed to be due to a particle rearrangement. A remarkable grain growth was observed shortly after this initial densification. The coarser c-WC powder showed the very similar sintering-behavior to the finer f-WC powder. This suggests that the smaller particles (-0.1 μ) contained in c-WC powder may play an important role in the densification. The sinterability of WC particles was higher in hydrogen than in vacuum at 1500°C, for which the difference in the chemical behavior of oxide layer (vaporization as oxide under vacuum and reduction in hydrogen) may be responsible.
