Studies on the Silicon Carbide Nano-Particulates reinforced Reaction Bonded Boron Carbide Composites

Abstract:

Reaction bonded boron carbide (RBBC) composites were fabricated based on molten Si infiltration method. The mechanical properties of the composites were improved by the reaction formed silicon carbide (SiC) nano-particulates. The role of SiC nano-particulates in the microstructure, density and mechanical properties of RBBC composites, and the strengthening mechanism were researched. The XRD results showed that the composites consist of four phases, namely, B4C, Si, reaction formed SiC and ternary phase B12(C,Si,B)3. The SiC nano-particulates were introduced in the RBBC composites by using phenolic resin as carbon sources. The bending strength, fracture toughness and Vickers-hardness of the RBBC composites fabricated with phenolic resin as carbon sources were 442 MPa, 4.9 MPa?m1/2 and 23 GPa, which increased of 35 %, 36 % and 15 % respectively, compared with those of RBBC composites fabricated with black carbon as carbon sources. Clearly, an introduction of the nano-sized SiC particles to RBBC composites is responsible for the increase in the mechanical properties of the composites.

Key words:reaction bonded boron carbide composites; Si infiltration; SiC nano-particulates; microstructures; mechanical properties