Non-destructive permeability measurements of porous graphene preforms via low-pressure gas flow

Infiltration is a newly developed method for preparing graphene reinforced metal matrix composites. Determining the permeability of graphene preforms is critical for achieving complete infiltration and identify the critical pressure. This work proposed a novel, non-destructive method to measure the permeability of porous graphene preform under low-pressure and low-velocity conditions, ensuring the preform remain intact. To understand the microstructure–permeability relationship, the porosity and microstructure of the preforms were analyzed and statistically evaluated. The gas flow channel in the testing apparatus was structurally optimized to ensure stable low-velocity flow and reduce gas pressure, enabling non-destructive characterization. Repeatability validation tests were conducted on preforms of a specific apparent density to evaluate the accuracy and error range of the non-destructive measurement. The permeability of preforms with varying apparent densities was then measured. For preforms with an apparent density in the range of 4.67-12.55 mg/cm3, the permeability was greater than 5.00×10−12 m2. For those in the 13.04-17.58 mg/cm3 range, the permeability was less than 5.00×10−12 m2. This study demonstrates that the low-pressure gas measurement method provides a novel, non-destructive approach for determining the permeability of porous nanomaterial preforms.