Investigations on sintering mechanism of nano tungsten carbide powder based on molecular dynamics simulation and experimental validation

Abstract

A Molecular Dynamics (MD) simulation using software LAMMPS and experimental validation for sintering of randomly distributed nano tungsten carbide (WC) powder has been done. The important aspects of the process i.e., neck width, dihedral angle, volume shrinkage, and diffusivity of particles have been analyzed. The maximum neck width and dihedral angle are found to be 5 nm and 100–120° respectively. The simulation results have been validated through microwave sintering of binderless WC. The solid-state sintering for pure nano WC powder has been performed at a temperature of 1450 °C. The volume shrinkage during simulation and experimental study show is approximately 32%. The simulation results for neck width and dihedral angle are comparable to experiment values. The diffusion coefficient for tungsten carbide during sintering at lower temperature through the simulation is found to be 2.05×10-11m2/s which is in good agreement with earlier research work on microwave sintering of binderless tungsten carbide powder. During displacement vectors analysis, it is found that smaller particles are pulled by large particles due to force of attraction which results in earlier neck formation. The sintered specimen has a hardness of 1760 Hv, and it shows an application of the final product as a cutting tool.