Ultrafast high-temperature sintering of polymer-derived ceramic nanocomposites for high-temperature thin-film sensors

Polymer-derived ceramic nanocomposites (PDC-NCs) are promising materials for high-temperature thin-film sensor (TFS) applications. However, owing to their inherent high-resistance characteristics and the high-temperature furnace sintering process, it is difficult to integrate PDC-NCs with high-conductive and low high-temperature tolerant alloy/metal components. In this study, an ultrafast high-temperature sintering (UHS) method was employed to prepare PDC-NC TFSs in minutes. The TiB2/SiCNO film sintered by the UHS technique shows high-sensitive microstructure and properties to sintering parameters. The UHS technique allows rapid sintering toward the desired phase, controls the grain size and microstructure, promotes the precipitation of free carbon in the SiCNO matrix within minutes, and suppresses high-temperature oxygen pollution. For example, TiB2/SiCNO films show high conductivity (18.1 S cm−1 at room temperature) and high-temperature stability (up to 800 ℃). In comparison, these properties are orders of magnitude better than those of samples sintered in the furnace. High-quality films sintered using ultrafast heating and cooling rates can also withstand thermal shocks of up to 1000 ℃. With the UHS technique, high-quality and high-conductivity films can be prepared using an ultrafast sintering rate to prevent substrate thermal damage. The TiB2/SiCNO thin-film strain gauge with high sensitivity (GF = 8.6) and low thermal noise was fabricated on alloy substrates, and its high-temperature (25–800 ℃) strain sensing performance was verified. This method offers a new route for co-sintering devices with alloy/metal substrates that suffer from low high-temperature tolerance and regulating the microstructure and electrical performance of these devices.