Synthesis of tungsten carbide–cobalt composites by the field-activated combustion synthesis method

Abstract

The activation of self-propagating combustion reactions in the tungsten carbide–cobalt (WC-Co) system was achieved by using an electric field. Self-sustaining combustion in elemental reactants with composition corresponding to WC- x wt.% Co (0 ≤ x ≤ 10) composites can be activated only when the imposed field is above a threshold value. The nature of combustion products depended on the magnitude of the field. The relative strength of W 2C diffraction peaks in XRD diagram decreased when moving from the reactants region to the final products one or increasing electric field on the reactants. The effect of the relative density of the reactant compacts on the synthesis of WC-Co composites was also investigated. Finally, the reaction mechanism of WC-Co composites was proposed. X-ray and microscopic analysis of the quenched combustion front suggests that the synthesis of WC is a process involving the solid diffusion of carbon into a carbide layer. Molten Co redounds the transformation from W 2C to WC phase.