The porosity of solids and powders is frequently characterized by mercury intrusion porosimetry. This technique provides detailed information on pore volumes, density, and pore-specific surface area, while also yielding information that can be used to characterize the shape and structure of pores.
To perform mercury intrusion porosimetry, various levels of pressure are applied to a sample immersed in mercury (a nonwetting liquid). As mercury is forced into the sample’s pores, pore size is calculated using as constraints mercury’s contact angle and surface tension. The pressure required to force mercury into the sample’s pores is inversely proportional to the diameter of the pores (when it is assumed that the pores are right circular cylinders).
Mercury intrusion porosimeters apply pressure to the sample in one of two ways:
All of Micromeritics’ mercury porosimeters offer both scanning and equilibrating by time. The AutoPore Series also offers equilibration by rate. At the present time, no known competitive instrument provides all of these capabilities.
Equilibrated analyses, particularly those equilibrated by rate, provide detail-rich, comprehensive, accurate porosity data. Scanning analyses are quicker, and produce highly repeatable data, but accuracy may be reduced. Scanning tends to show smaller intrusion volumes and smaller pore sizes, so it is best-suited for applications in which repeatability is more important than accuracy, such as certain types of quality-control sampling.
Understanding why scanning and equilibrated data may differ significantly is useful when selecting a method.
The porosity of solids and powders is frequently characterized by mercury intrusion porosimetry. This technique provides detailed information on pore volumes, density, and pore-specific surface area, while also yielding information that can be used to characterize the shape and structure of pores.
To perform mercury intrusion porosimetry, various levels of pressure are applied to a sample immersed in mercury (a nonwetting liquid). As mercury is forced into the sample’s pores, pore size is calculated using as constraints mercury’s contact angle and surface tension. The pressure required to force mercury into the sample’s pores is inversely proportional to the diameter of the pores (when it is assumed that the pores are right circular cylinders).
Mercury intrusion porosimeters apply pressure to the sample in one of two ways:
All of Micromeritics’ mercury porosimeters offer both scanning and equilibrating by time. The AutoPore Series also offers equilibration by rate. At the present time, no known competitive instrument provides all of these capabilities.
Equilibrated analyses, particularly those equilibrated by rate, provide detail-rich, comprehensive, accurate porosity data. Scanning analyses are quicker, and produce highly repeatable data, but accuracy may be reduced. Scanning tends to show smaller intrusion volumes and smaller pore sizes, so it is best-suited for applications in which repeatability is more important than accuracy, such as certain types of quality-control sampling.
Understanding why scanning and equilibrated data may differ significantly is useful when selecting a method.
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