Stress Measurements in ZrB₂-SiC Composites Using Raman Spectroscopy and Neutron Diffraction

Raman spectroscopy and neutron diffraction were used to study the stresses generated in zirconium diboride-silicon carbide (ZrB2-SiC) ceramics. Dense, hot pressed samples were prepared from ZrB2 containing 30 vol% α-SiC particles. Raman patterns were acquired from the dispersed SiC particulate phase within the composite and stress values were calculated to be 810 MPa. Neutron diffraction patterns were acquired for the ZrB2-SiC composite, as well as pure ZrB2 and SiC powders during cooling from ∼1800 °C to room temperature. A residual stress of 775 MPa was calculated as a function of temperature by comparing the lattice parameter values for ZrB2 and SiC within the composite to those of the individual powders. The temperature at which stresses began to accumulate on cooling was found to be ∼1400 °C based on observing the deviation in lattice parameters between pure powder samples and those of the composite.