Making ceramic composites by melt infiltration

Pressureless sintering of monolithic ceramics results in substantial shrinkage as the void space in the initially porous starting material is eliminated. Introduction of fibers or platelets inhibits sintering. Thus, when ceramic composites are made, processes other than sintering are used to achieve dense structures or to control the shape and size of the final material. These processes are either consolidation or infiltration methods. Nonreactive and reactive methods of melt infiltration are compared with other processes for making ceramic-matrix composites. Reaction-bonded Si/SiC composite illustrates reactive infiltration. A model that better predicts infiltration times than does the classic Washburn model is presented.