Effect of the number of graded layers on the microstructure and properties of SiC/C functionally graded materials

SiC/C bulk functionally graded materials (FGMs) with different numbers of graded layers (N) for fusion technology were designed and fabricated successfully by a power stacking method and hot-pressing process under the pressure of 30 MPa at 2000 °C. Results showed that the number of graded layers (N) had marked effect on the microstructure and properties of the as-received SiC/C FGMs. SEM examinations indicated that interfaces between the adjacent layers faded out gradually and became more linearly continuous gradient with increasing number of graded layers, which led to marked improvement in the bend strength and thermal shock resistance of the samples. Water quenching tests with a temperature difference of 500 °C showed that SiC/C FGMs with N > 8 had the best thermal shock resistance for the materials studies, and no cracks occurred after 90 quench cycles.