Reactive hot pressing of ZrB2-SiC composites

A ZrB2-SiC composite was prepared from a mixture of zirconium, silicon, and B4C via reactive hot pressing, The three-paint bending strength was 506 +/ - 43 MPa, and the fracture toughness was 4.0 MPa.m(1/2). The microstructure of the composite was observed via scanning electron microscopy; the in-sit u-formed ZrB2 and SiC were found in agglomerates with a size that was in th e particle-size ranges of the zirconium and silicon starting powders, respe ctively. A model of the microstructure formation mechanism of the composite was proposed, to explain the features of the phase distributions. It is co nsidered that, in the reactive hot-pressing process, the B and C atoms in B 4C will diffuse into the Zr and Si sites and form ZrB2 and SiC in situ, res pectively, Because the diffusion of Zr and Si atoms is slow, the microstruc ture (phase distributions) of the obtained composite shows the features of the zirconium and silicon starting powders.