The solution-precipitation processes of liquid-phase sintering are very essential because they effect not only the sintering state of ceramics, but also their phase composition and microstructure. These processes may be considered from the high-temperature corrosion standpoint, i.e. solid particles are effected by very active melt (in many cases, molten silicates) at high temperature. In this case, some mathematical expressions from the corrosion process of refractories in molten metals, slags, and glasses may be utilized; however, small particle size of the solid and anisothermal conditions should be taken into consideration. The essential factors that determine the solution-precipitation of liquid-phase sintering are the temperature of the liquid phase formation, the change of composition and structure of liquid phase with increase in temperature, and also the initial conditions of the solids.