TiB2‐Modified Polymer‐Derived Ceramic SiCN Double‐Layer Thin Films Fabricated by Direct Writing for High‐Temperature Application

The thermal stability at high temperatures is the first design principle of high‐temperature thin‐film sensors. To improve the thermal stability of the thin‐film sensor, a TiB 2 ‐modified SiCN double‐layer thin‐film resistor grid with a thickness of 18 μm is fabricated on an alumina substrate via direct writing. Owing to their in situ–generated SiO 2 –B 2 O 3 –TiO 2 thermally grown oxide protective layer on the surface and TiB 2 percolation paths inside, the produced films exhibit large high‐temperature oxidation resistance, electrical conductivity and high‐temperature‐resistance stability. In the thermal cycling test up to 800 °C, the TiB 2 ‐modified SiCN films exhibit a negative‐temperature coefficient of resistance and excellent repeatability and stability. The resistance change rate at 800 °C for 1 h is only 1.1%. With the flexible manufacturing and high‐temperature stability of such ceramic films, this work on double‐layer ceramic films can be applied to in situ monitoring of hot components at high temperature.