Characterization of the average pore diameter of nanoporous media by gas permeability measurement technique in transitional flow regime. (December 2021)

• Record Type: Journal Article
• Authors: Wang, Xudi; Chang, Renchao; Ding, Yunsheng; Zhou, Bin; Cao, Qing; Bi, Hailin
• Is Part Of: Vacuum. Volume 194(2021)
• Publication Date: 2021-12
• Subjects: Transition flow -- Conductance -- Nondestructive testing -- Porous material; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2021.110596
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: In this paper, a gas permeability measurement technique in transitional flow regime was proposed, which could characterize the average pore diameter of nanoporous media non-destructively. With high purity argon and carbon dioxide, the conductance of three groups of porous anodic alumina was tested respectively in the transitional flow regime by the dynamic differential pressure attenuation test system, and the average pore diameter of porous anodic alumina was derived. The average pore diameters obtained through the gas permeability measurement technique are consistent with the SEM image analysis results, and the relative error is less than 8%. This method based on the improved transitional flow conductance theory extends the pore-size range of gas permeability measurement technique from micrometer to the nanometer scale, and does not require high pressure or high vacuum. It has the advantages of non-destruction, high-accuracy and large-area-measurement, which brings significant practical application value. Highlights: Gas permeability measurement technique in transitional flow can characterize the average pore size of nanoporous media. The basic theory is using the linear relationship between the gas conductance and the reciprocal of gas mean free path. The positions of the Knudsen Minimum can be taken as a reference to select the appropriate conductance data. This method extends the pore-size range of gas permeability measurement technique from micrometer to nanometer scale.