Appendix B GRADED STRUCTURES BY CENTRIFUGAL CASTING

Centrifugal casting offers greater potential for graded structure manufacture than gravity. The main reason for this is the higher pressure in the melt, which facilitates infiltration in a graded preform. Another reason is that usually the centrifugal force exceeds essentially the gravitational force, and because of this particles in composite slurry move faster than in the case of gravity casting. Moreover, by management of rotation speed one can control the magnitude of the centrifugal force, which means to control particle velocity in liquid composite during solidification. The latter is impossible in gravity casting and gives an important advantage of centrifugal casting for production of a variety of graded structures. A comprehensive mathematical model based on equations for both particle movement and solidification in rotating slurry, which would be capable of describing macrostructure formation in centrifugal casting of particle reinforced MMCs will be presented and short discussion on its application to the manufacture of graded structures will be analyzed.