Influence of graphene coating structure on the hydrodynamic properties of porous media

Abstract

In light of the growing interest in carbon-based coatings, this paper investigates the influence of graphene coatings on the main hydrodynamic characteristics of sintered porous media. We developed a consistent methodology for coated porous medium characterization, which involves measurement techniques for the three most important parameters: porosity, capillary pressure, and permeability. The latter required special attention because of the coating fragility, which prevented the application of the conventional forced flow method. Thus, a mass rate-of-rise principle has been used, where the absorbed liquid mass is monitored in time and then fitted to the Lucas-Washburn model. The model's validity is strictly proven for the particular experimental conditions and the samples, as well as the rigorous theory for uncertainty estimation in the case of the least squares method. Using a pressing technique, the authors created porous samples of stainless-steel 316 L polydisperse and nickel spherical particles. The graphene coating is applied by the chemical vapour deposition technique. We found that the coating reduces the porosity and permeability of the nickel samples and increases their capillary pressure, with this influence proportional to the synthesis time. Conversely, the stainless-steel 316 L samples evidenced unintuitive results with 3D disordered carbon addition. The variation in porosity and permeability is within the measurement uncertainty, and capillary pressure exhibits an inverse dependence on the deposition process time. The measurement results are correlated with the analysis of the porous space structure and the coating structure obtained by SEM imaging and Raman spectroscopy.