A Quantitative Assessment of the Mechanical Preparation of Sintered Iron Micrographic Specimens

Abstract

The examination of P/M microstructures by automated image analysis requires a reproducible high level of surface finish from the section of the specimen under investigation. The preparation of mechanically polished sections involves a number of procedures each susceptible to variation. The effect of variations taken together can be large, resulting in erroneous information. A quantitative assessment of each procedure for polishing specimens from an iron P/M system has been conducted using automated polishing machines. The porosity of sintered iron compacts was measured using an automated image analysing computer. The ‘measured’ porosities were compared with the ‘true’ bulk porosity in each case to assess the variation due to each polishing parameter. Although a universal set of polishing conditions cannot be given, the results enable a set of optimized polishing conditions to be derived.