A theoretical analysis of solution-precipitation controlled densification during liquid phase sintering

Models for solution-precipitation controlled, intermediate stage liquid phase sintering (LPS) have been derived by assuming a tetrakaidecahedron grain geometry with cylindrical pore channels along the grain edges and incorporating the liquid content and dihedral angle by adapting Wray's two phase grain model. The stress distribution of a thin liquid film between the grains is modelled as a hydrostatic squeeze film. The model predicts that a thin viscous liquid film is stable and suppors the normal stress arising from the Laplacian force at the liquid-vapor interface. The derived equations for both diffusion and interface reaction controlled liquid phase sintering show significant differences with respects to Kingery's LPS models, but are in good agreement with those based on liquid phase controlled creep models. Comparative analyses of the derived models indicate that the rate controlling mechanism during solution-precipitation shifts from diffusion to interface reaction control or vice versa as a function of particle size and/ or grain growth.