Role of powder morphology in liquid phase sintering of binder jet additively fabricated WC–Co composite

Abstract

The present study explored the computational analysis of capillary forces and capillary pressure experienced by the liquid present between particles of various morphologies during liquid phase sintering of a binder jet additively fabricated WC–10 wt% Co composite. An integrated two-particle computational approach was adopted for morphologies gradually transitioning from spherical to cubical. The capillary forces depended on factors such as curvature of liquid meniscus, volume of liquid present between two neighboring particles, and changes in solid–liquid and liquid–vapor contact areas, which were influenced by the particle morphology. The results indicated that capillary forces increased as particle morphology changed from spherical to non-spherical, while increased particle separation led to a reduction in capillary force. Despite increased particle separation, the overall trend in effect of particle morphology on capillary force remained consistent. Additionally, a probability density function based on Rayleigh distribution was used to represent particle separation distances in a real system and variations in coordination number due to different particle morphologies and separation distances were considered. This model allowed estimation of overall effect of particle morphology on capillary force and capillary pressure in realistic systems. The model-based predictions confirmed the experimental observations of severely limited sintering in binder jet additively fabricated WC–10 wt% Co composite containing spherical particles compared to that containing the particles of irregular morphologies. This study provides valuable insights into the mechanics of capillary forces, capillary pressure, and their role in liquid phase sintering, with potential applications in the design and optimization of components of any material system produced using any additive manufacturing process involving liquid phase sintering.