Microstructure and properties of bilayered B4C-based composites prepared by hot-pressing

Bilayered B4C-based composites were prepared by hot-pressing method. One layer was a B4C ceramic layer using C and Ti powders as sintering assistants. The other layer was a B4C ductile layer named as BST layer, in which TiC, Si and Ti mixed powders were added to synthesize Ti3SiC2 phase to improve toughness of B4C. Although XRD results showed that no Ti3SiC2 was found in the BST layer, SEM and EDS analyses proved that trace amount of lamellar Ti3SiC2 structure was observed under high magnification fractographs in the BST layers with additive contents (x) equal to 30 and 40 wt%. Both the flexural strength and fracture toughness of the bilayered B4C-based composite increased with the increase in the amount of additions in the BST layer, reaching optimum values of 550 MPa and 6.6 MPa m1/2 at x = 40 wt%, respectively.