Effect of WC or ZrC addition on thermal residual stresses in ZrB2[sbnd]SiC ceramics

Abstract

The residual stresses in ZrB2SiC ceramics with the addition of WC or ZrC were measured using Raman spectroscopy (RS) and X-ray diffraction (XRD). The temperatures at which the residual stresses began to accumulate were calculated. The resistance to high-temperature deformation of ZrB2SiC-based ceramics was evaluated via four-point flexure test under a static load (15, 25MPa) for 5h at 1600°C and 1800°C. The results indicate that a compressive residual stress existed in SiC particles and a corresponding tensile stress applied in ZrB2 matrix. The values of thermal residual stresses increase in order of ZSZ (ZrB2SiCZrC)<ZS (ZrB2SiC)<ZSW (ZrB2SiCWC). The temperature composite begin to accumulate the residual stresses also increases in the same order. The apparent different behaviors are resulted from their dissimilar grain boundary state and third phase nature in three ceramics. The phenomenon was explained by a proposed model. The results provide a path to design material compositions with an ideal mechanical properties and guidance role for applications.