High temperature impact response of silicon nitride ceramics

Abstract

The internal friction of silicon n A composite sphere model in the microstructure was established to describe the viscoelastic behaviors of Si3N4 ceramics.itride ceramics at elevated temperature and under impact loading was investigated experimentally and analytically. Impact tests of ceramics at elevated temperature up to 1400 °C were performed using the split Hopkinson pressure bars and the long length specimens. A method for determining viscoelastic mechanical property from test results was proposed. The internal friction of ceramics at the frequency of 5.9 kHz and elevated temperature was evaluated. Assuming that a single thermal activation mechanism controlled the viscous behavior at the range of test temperature, a composite sphere model in the microstructure was established to describe the ceramics viscoelastic behavior. A mechanical model of spring and dash-pot was deduced to explain the test results.