Thermodynamic modeling and experimental study of protective barriers against carbon diffusion during spark plasma sintering process

Abstract

During spark plasma sintering (SPS), the contact between the graphite tooling and the powder results in carbon diffusion. Graphite foils coated with a physical vapor deposition (PVD) film represent a promising solution to overcome this issue. In the present work, simulation and experiments were combined to understand the barrier effectiveness against carbon diffusion of a titanium PVD film deposited on graphite foils used during SPS of an iron powder. In non-equilibrium processes, simulation alone is insufficient to describe the multiple diffusion scenarios. On the other hand, experimental measurements are not always relevant. The approach adopted in this work enabled the prediction of the potential phases that form as a function of diffusion depth. Several scenarios were proposed, helping to explain the influence of the film thickness. This methodology, applied to the C-Ti-Fe system, can be extended to other film-substrate couples, reducing the number of tests and the associated costs.