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Abstract
An experimental investigation has been performed in order to explain the microscopic interaction between the powder compact, lubricant and tool wall during powder pressing. Interference microscopy was used to characterise the compact topography, X-ray photoelectron spectroscopy and scanning electron microscopy were used to analyse the lubricant distribution on the compact surface. Water atomised iron powder, compacted at 600 MPa, with ethylene bisstearamide content <1 wt-%, was determined to be covered by a monomolecular film of lubricant. The volume of surface porosity was identified as a key parameter that will determine the minimal lubricant content to achieve lubrication. On debinded components, this volume has been determined experimentally to 0·4 μm3 per μm2 for compaction pressures between 400 and 800 MPa. On green compacts, with lubricant contents between 0·6 and 1 wt-%, 1% of this volume will be unfilled by lubricant, at 0·5 wt-% this value will increase to 20%.