Sensing Properties of Nanocrystalline Silicon Carbide in Wet Condition

Silicon carbide is a well-known material with high thermal and chemical stability. In this work, we present an investigation on the chemoresistive properties of nanostructured Silicon Carbide (SiC). A commercially available nanopowder of silicon carbide was first purified and then its morphology, structure and thermal stability was characterized. Afterwards, the powder was mixed with suitable organic vehicles and screen-printed onto alumina substrates. SiC thick films were tested as chemoresistive gas sensors in thermo-activation mode. In this way, they were exposed to 13 gases belonging from different chemical classes. The sensing characterization showed that this semiconductor is an extremely selective functional material for the detection of sulphur dioxide (SO2) at temperature higher than 600°C, useful for harsh environments. Also, the sensing properties of SiC sensors were strongly improved by the presence of humidity. The sensing mechanism was also investigated and a possible interpretation has been proposed.