Fabrication of high gas-tightness SiCN ceramic via PIP process for increasing sensing distance of pressure sensor

High-gas-tightness wireless pressure sensors were fabricated by using a silicon carbonitride (SiCN) ceramic material derived from liquid polyvinylsilazane (PVSZ) precursor via precursor infiltration and pyrolysis (PIP) process. In order to increase the density of ceramic disks effectively, two types of infiltration liquids were chosen; PVSZ/Ethanol (2:1) with high viscosity was designed for the first cycle of PIP process, while PVSZ/Ethanol (1:1) with low viscosity was designed for the last two cycles of PIP process (The ratio in the parentheses represents the content of PVSZ and ethanol, respectively). The results confirmed that the density of ceramic disk after three PIP cycles can be increased to 2.155 g/cm(3). Gas tightness measurement of ceramic disks indicated that the gas tightness was improved obviously after PIP cycles, and ceramic disks after the 2nd and 3rd PIP cycles could keep gas-tight condition without loss of pressure after 8 days. In addition, because high density was detected in the ceramic disks after PIP cycles, the wireless pressure sensors with large sensing distance have been fabricated.