Boron Carbide-Based Nanostructured Composite by Spark Plasma Sintering

Abstract

In the current paper, we present the use of nanostructured boron suboxide (B6O) and in-situ synthesized hexagonal boron nitride (hBN) to form structured composites with commercially available boron carbide (B4C). Taking advantage of the rapid heating rate of Spark Plasma Sintering (SPS), structured composite could be produced by to limiting the grains growth and phase segregation. Characterisation of the composite structures and mechanical properties were carried out using electron microscopy techniques, X-ray diffraction and micro/nano-indentation test. Results have shown that the optimised mix of B4C sintered with nanostructured B6O could achieved a high hardness of 40 GPa and fracture toughness of 4.82 MPa.m1/2. Using a reactive-SPS technique to sinter B4C in nitrogen gas environment, a unique core-shell structure of B4C-hBN was produced. Nano-indentation test of the B4C-hBN composite shows that an average high local hardness of 56.7GPa was achieved.