Encapsulation of Powder Mixtures with Frozen Fluids by Pressing

A composite consisting of ice and a mixture of iron powder and zinc stearate that was prepared by freezing at –(6–8)°C has been pressed in a steel die for the first time. The porosity and extrusion pressure of the composite pellets are close to those in dry pressing at room temperature. The frozen cores consisting of ice and various powders have been encapsulated for the first time by joint pressing with a fully encapsulating mixture of iron powder and zinc stearate in dry state. The average porosity of the encapsulated core compacts subjected to drying and sintering is determined by the core properties, i.e., by the material being encapsulated. The use of direct and reverse water–ice transformations has been found to be promising in compaction processes.