Porosity analysis of PM materials by helium pycnometry

Abstract

A method to estimate the pore free density and the open and closed porosities of a PM specimen by helium pycnometry is introduced. The findings of the method as applied to pressed and sintered specimens of a commercially pure iron powder in the density range from 6·7 to 7·5 g cm⁻³ are presented and compared with the values obtained on the same specimens using the standard oil impregnation and water immersion method. It was found that the observed density values by the two methods were similar, but that the open and closed porosity values were not. In general, the pycnometric method indicated substantially higher open porosity values and correspondingly lower closed porosity values than the standard method at all densities.

Keywords

FERROUS PM POROSITY HELIUM PYCNOMETRY LIQUID IMPREGNATION

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