Derived from the Greek word ‘poros’ meaning passage, porosity is a critical parameter used to describe and quantify the internal structure of many materials of industrial interest. Porosity defines the ease with which fluids can travel through a solid, the extent and accessibility of internal surface area and relationships between strength and weight. Examples of products for which porosity is a performance-defining characteristic include: catalysts; construction materials; ceramics; pharmaceuticals; membranes and filters; active elements of batteries and fuel cells; and the finished components produced by metal manufacturing methods such as additive manufacturing (AM) and metal injection molding. Porosity characterization is equally essential for the effective exploitation of oil and gas bearing reservoirs.
Practical techniques used to investigate porosity include pycnometry, gas adsorption, mercury porosimetry and porometry. Mathematical manipulation of the resulting measurements enables characterization to varying degrees of detail, with alternative approaches optimal for different materials and for analysis over different length scales. This paper takes an introductory look at these techniques, the data generated and their strengths and limitations for specific materials, covering more complex approaches such as the Reverberi method and the application of non-local density functional theory (NLDFT) to illustrate the necessity for, and potential benefits of, more advanced analysis.