Conductivity of SiCNO-BN composite ceramics and their application in wireless passive temperature sensor

SiCNO-BN composite ceramics were synthesized by polyvinylsilazane and hexagonal boron nitride. It was found that the electrical conductivity of SiCNO-BN composites varied nonmonotonically with BN content. According to the scanning electron microscope and Raman spectroscopy analysis, we can conclude that the conductive behavior of SiCNO-BN composites was strongly related to the graphitization degree of free carbon in the SiCNO-BN composites. Compared with SiCNO ceramic, the conductivity of the SiCNO-BN composite decreased from 1.68 × 10−8 (Ω cm)−1 to 4.41 × 10−9 (Ω cm)−1 when the content of BN was 15 wt%, and the graphitization degree of free carbon also decreased dramatically. The dielectric loss of SiCNO-BN composites was also reduced as the conductivity of SiCNO ceramic decreased. In addition, one of the potential applications of polymer derived ceramics (SiCNO) is high-temperature sensors. However, its real application process is limited. In order to solve this problem, the wireless passive temperature sensors based on SiCNO-BN composite ceramics were fabricated. The results showed that the maximum measurement temperature of SiCNO-BN temperature sensor with 15 wt% BN can reach up to 1250 °C, which is higher than 900 °C of the SiCNO temperature sensor.