ASTM B328 – Standard Test Method for Density, Oil Content, and Interconnected Porosity of Sintered Metal Structural Parts and Oil-Impregnated Bearings (Withdrawn 2009)
Significance and Use
The volume of an arbitrary P/M shape cannot be accurately measured by standard techniques such as by micrometers or calipers. Since density is mass/volume, a precise method to measure the volume is needed. For nonporous objects, the volume of water displaced by the immersed object is determined by Archimedes principle. For porous P/M parts, a method is required to seal surface connected pores. If the pores are not sealed or the part is not oil impregnated, the part will absorb some of the water and decrease its buoyancy and exhibit an erroneously high density.
Density and oil content values are generally contained in the specifications for oil-impregnated bearings and other self-lubricating P/M parts. Desired lubrication requires sufficient interconnected porosity and satisfactory oil impregnation of the porosity.
For a particular P/M material, the mechanical properties of P/M structural parts are directly related to their density. Density values are therefore generally contained in the specifications for P/M parts.
1.1 This test method covers determination of the density, oil content, and interconnected porosity of sintered bearings and structural parts with or without oil impregnation.
1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.