The Infiltration of Lubricants into a Porous Briquette, When Compacting

The migration of the boundary layer of lubricant into a porous briquette during compacting is investigated. It is found out that the density of briquettes compacted of a mixture of iron and graphite powders with the addition of animal fat hardly increases with increasing holding under the load, while the ejection pressure increases substantially. It is assumed that the ejection pressure increases due to the infiltration of a lubricant (from the layer between briquette and die wall) into the pores of the briquette. This leads to thinning disrupting the continuity of the lubrication layer and, accordingly, to increasing the external contact friction. The conducted studies allow not only predicting the behavior of viscous lubricants, but also enhancing the possibilities of impregnating the briquettes sintered under high pressure in the die in vacuum.