Effect of Oxygen Adsorbed by Tungsten Carbide Nanopowders on the Densification Kinetics and Properties of Spark Plasma Sintered Ceramics

The influence of adsorbed oxygen on the properties of samples and the kinetics of spark plasma sintering of pure tungsten carbide and hard alloy powders has been investigated. It is shown that oxygen leads to the formation of W2C and η - phases in pure tungsten carbide and in hard alloys, respectively. It was found that adsorbed oxygen does not significantly affect the shrinkage kinetics of powder compacts. The activation energy of the intensive second stage of sintering of pure tungsten carbide and hard alloy powders was 9 and 12 kTm, respectively. Samples of pure tungsten carbide were characterized by high values of hardness (near 25 GPa) and crack resistance (4.7 MPa·m1/2).