Processing Techniques of Functionally Graded Composites-The Current Status

The advantage of composite materials is the high stiffness-to-weight and strength-to-weight ratios. The limitation of composite materials is debonding of the reinforcement from the matrix which occur under two conditions-a weak interface and mismatch of thermal and mechanical properties between the reinforcement and the matrix leading to a buildup of residual stresses. The problems have been overcome to some extent by improving the interface problems, using better reinforcements like particulates and whiskers and minimizing the residual stresses by suitably selecting the matrix and reinforcements. One answer to overcome the limitations is to use functionally graded materials (FGM's). This paper reviews the various processing techniques of FGM's and the current research work done.