Piezoresistive Ceramics for High-Temperature Force and Pressure Sensing

Here we report on the high-temperature piezoresistivity of carbon-containing silicon oxycarbide nanocomposites. Sam-ples with contents of segregated carbon of 13.5 vol% were prepared from a polysilsesqioxane via thermal cross-linking, pyrolysis and subsequent hot-pressing. Their electrical resistance was assessed as a function of the mechanical load (1 -10 MPa) and temperature (1000 - 1200 deg C). The piezoresistive behavior of the C/SiOC nanocomposites relies on the presence of a disordered sp(exp 2) - sp(exp 3) carbon network, as revealed by Raman spectroscopy. C/SiOC exhibits enhanced k fac-tor values as compared to highly-ordered graphite (HOPG) or graphene, though lower than those reported for similar C/SiOCN nanocomposites. In view of the measured k values of about 40 at the highest temperature reading (T = 1200 deg C), C/SiOC is a primary candidate for high-temperature piezoresistive force and pressure sensors.