Model of molding of piezoceramics under pressure

The simple model of molding at a constant temperature is presented for the first time. Process of molding is considered as a sequence of phase transit ions between different macroscopically defined states (phases): granulated powder, dispersed crystalline state and polycrystalline state. The theory p redicts that intermediate states must be considered as separate phases exis ting at a definite constant pressure. Intermediate states compressibility e xceeds compressibilities of surrounding phases. After removal of the pressu re the specimens in the intermediate state lose theirs strength with respec t to the subsequent mechanical processing.