In situ temperature monitoring of ceramic matrix composites (CMCs) under extreme high-temperature conditions is critical for thermal safety management. However, existing thin-film sensors suffer from cracking and signal drift in their sensitive layers due to the spatial heterogeneity of the CMC matrix’s coefficient of thermal expansion and high-temperature interfacial degradation. Here, a multiscale synergistic regulation strategy is proposed. First, the distribution characteristics of CMC fiber volume fraction are quantified using a Weibull random field model, guiding the design of a TiB₂/B₂O₃ gradient transition layer. Leveraging the viscoelastic transition of B₂O₃ within the temperature range 450–1860 ℃, dynamic thermal stress dissipation is achieved, reducing interfacial shear stress by 62%. A 3D interpenetrating thermal expansion matching layer is constructed using micro/nano SiC composite powders, enhancing interfacial bonding strength to 19.7 MPa. An Al₂O₃ insulating layer is subsequently fabricated to improve electrical insulation. Finally, an indium tin oxide/In₂O₃ thermocouple-sensitive layer is deposited via Weissenberg direct writing, utilizing a polymer-derived ceramic solution as the powder solvent. The resulting sensor exhibits exceptional performance in static air at 1100 ℃: thermoelectric response linearity (R² > 0.999), a Seebeck coefficient of 168.65 μV/℃, and a low thermoelectric potential drift rate of 1.27%/h over 8 h. This study provides a theoretical foundation and technological prototype for high-precision health monitoring of hot-section components in aeroengines.

Conformal thin-film sensors enable precise monitoring of the operating conditions of components in extreme environments. However, the development of these sensors encounters major challenges, especially in uniformly applying multiple film layers on complex metallic surfaces and accurately capturing diverse operational parameters. This work reports a multi-sensor design and multi-layer additive manufacturing process targeting spherical metallic substrates. The proposed high-temperature dip-coating and self-leveling fabrication process achieves high-temperature thin-film coatings with excellent uniformity, high-temperature electrical insulation, and adhesion properties. The fabricated Ag/Pt thin film thermocouple arrays and a heat flux sensor exhibit a maximum temperature resistance of up to 960 ℃, with thermoelectric potential outputs and high-temperature resistance closely mirroring those of wire-based Ag/Pt thermocouples. Harsh environmental testing was conducted using high-power lasers and a flame gun. The results show that the array of thin-film conformal thermocouples more accurately reflected temperature changes at different points on a spherical surface. The heat flux sensors achieve responses within 95 ms and withstand environments with heat fluxes over 1.2 MW/m². The proposed multi-sensor design and fabrication method offers promising monitoring applications in harsh environments, including aerospace and nuclear power.