Liquid-phase sintering particle rearrangement

The mechanisms of liquid-phase sintering processes have been described in detail by Kingery (213, 214], Petzow (215), and German [216]. The sintering process can be treated as a sequence of three stages particle rearrangement solution-reprecipitation and skeleton sintering. 

Promotion of particle rearrangement and grain growth through liquid phase sintering,... 

Densification results from particle rearrangement under the influence of capillary forces and the filling of pores by the liquid phase. This process is very rapid, and if during the early stages of sintering, the liquid flows and completely fills the finer pores between the particles, 100 percent densification can result almost instantaneously. 

A schematic of a typical shrinkage curve for the three phases of sintering is shown in Fig. 10.25 (note the log scale on the. v axis). Relative to the other two processes, particle rearrangement is the fastest, occurring in the time scale of minutes. The other two processes take longer since they depend on diffusion through the liquid or solid. 

The liquid dissolves the surface asperities and also dissolves the small particles. The granular rearrangement is limited to the hquid phase sintering itself, but it can be enough to allow complete densification if the hquid phase is in sufficient quantity, as is the case in the vitrification of sihcate ceramics ... 

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