Preparation and mechanical properties of laminated zirconium diboride/molybdenum composites sintered by spark plasma sintering

Abstract

Laminated ZrB2/Mo composites, alternately consisting of matrix layers of 80 vol.% ZrB2 + 10 vol.% nano-SiC whiskers + 10 vol.% SiC particles and Mo interlayers, with the addition of Si and B as interlayer adjusting agent, were prepared by roll-compaction and spark plasma sintering (at 1600°C) process. XRD and SEM techniques were used to characterize the phases and microstructure of the obtained composites. The results showed that without the addition of Si and B in the interlayer, interfacial debonding between the matrix layer and interlayer often occurred due to the thermal mismatch between the two kinds of layers. However, the interfacial mismatch could be effectively inhibited by the addition of Si and B to the Mo interlayers. The laminated ZrB2/Mo composites with 6 at.% Si and 4 at.% B in the interlayers showed the highest bending strength at (451±20) MPa and the highest fracture toughness at (7.52±0.12) MPa·m½. MoB, ZrB and Mo5SiB2 were formed by the reactions among ZrB2, Mo and the additions.