Effects of hBN and Y2O3 Addition on Mechanical and Tribological Behavior of SiC Ceramic Matrix Composites Prepared by Spark Plasma Sintering

The objective of the present work is to study the mechanical and tribological properties of SiC-hBN such as hardness, density, fracture toughness, friction and wear behavior with and without additives. Therefore, SiC-hBN composite with different composition of hBN (0, 5, 10, and 35 vol. %) and 2 vol.% sintering additive Y2O3 was fabricated by spark plasma sintering at 1800 degrees C with 55 MPa load for 5 min. under argon atmosphere. SEM-EDS and XRD were used for the microstructural evaluation and characterization of the composite. The hardness of the composite shows a decreasing trend from 19.20 MPa to 16.73 MPa while fracture toughness increases from 2.33 MPa-m(1/2) to 3.93 MPa-m(1/2), when the hBN volume fraction increases from 5 to 35 vol. % in the composite. The wear and friction behaviour of composites were studied through ball-on-disc wear test rig without lubrication. The wear volume, wear track width, as well as coefficient of friction, decreased by increasing the h-BN volume fraction. The size and shape of debris particles decreased uniformly as the hBN content increases, whereas non-uniformly wear debris was observed in the additive-free composite. The composites with additives showed excellent mechanical and tribological performance as compared to additive-free composites.