Self-monitoring of strain in silicon carbide whisker reinforced silicon nitride

An Si₃N₄-matrix composite with 30 vol.% SiC whisker was found to be able to sense its own tensile strain, including reversible strain, but not compressive strain. The sensing ability is based on the volume electrical resistivity of the composite reversibly decreasing upon tensile loading. The effect is attributed to the reversible decrease in the contact electrical resistivity at the whisker-matrix interface for whiskers that are somewhat parallel to the stress.