Method of Pore Size Distribution Measurement

The typical methods to measure the pore size distribution of power and materials are the gas adsorption and mercury porosimetry. The pore size distribution from the gas adsorption method is commonly analyzed from the nitrogen or Ar adsorption isotherm at their boiling temperature, and it is possible to evaluate the pore size from the molecular size to a few hundred nm. The realistic largest detectable pore size is just over 100 nm due to the restriction from the pressure sensor accuracy and temperature stability of coolant. Mercury porosimetry calculates the pore size distribution by pressurizing mercury, which is non-wetting, and measure the corresponding intrusion amount. By this method, it is possible to detect the pore size from a few nm to 1000 µm within a short period of time. For the pore size measurement below 10 nm, it requires over 140 MPa of pressure for the intrusion of mercury, so it is necessary to make sure that the material has the strength to withstand the pressure. Also, by this method, it evaluates the pore size of inkbottle neck (the smallest diameter of the pore) from the principle. The realistic measurement range is from a few 10 nm. Recently, there are bubble point method and gas permeation method to measure the through pore size of filters and separation membranes.

Determination of pore size distribution