Development and investigation of densification behavior of ZrB2-SiC composites through microwave sintering

Zirconium Diboride (ZrB2) ceramic has applications in refractory and foundry industries owing to the high melting point temperature. The densification of ZrB2 to nearly full density is difficult due to covalent bonding and surface impurities but the addition of Silicon Carbide (SiC) not only increases the densification but also improves the mechanical and thermal properties. In conjunction with SiC, ZrB2 ceramic finds extensive applications in ballistic armors, cutting tools, rocket propulsion and leading edges of atmospheric re-entry vehicles. The aim of study is to develop and examine the densification behavior of ZrB2-30 vol% SiC composites by microwave sintering. Microwave sintering of ZrB2-SiC composites is carried out varying sintering temperature (1600 degrees C-1900 degrees C), holding time (30-50 min) and heating rate (15-35 degrees C min(-1)). The composites thus developed are characterized using SEM and XRD techniques. Microstructural analysis has exhibited a homogeneous dispensation of SiC reinforcement in the ZrB2 matrix. XRD analysis has revealed the pattern behavior and crystalline phases present in the developed composites. The fully dense composites with highest relative density of 97.35% and vickers hardness of 16.79 GPa are achieved at the sintering temperature of 1800 degrees C, holding time of 40 min and heating rate of 15 degrees C min(-1). The highest fracture toughness is observed as 5.10 Mpa.m(1/2) at sintering temperature of 1700 degrees C, holding time of 40 min and heating rate of 25 degrees C min(-1).