Conformal Fabrication of Functional Polymer-Derived Ceramics Thin Films

Polymer-derived ceramics (PDCs) is considered to be a promising material for extreme environments such as aero-engine and hypersonic vehicles. However, current methods for PDCs thin films focus on 2D forms, hindering the applications for 3D curved structures where the majority of objects hold complex curvilinear surfaces. To overcome these limitations, a new conformal 3D printing system was developed for in situ preparation of the PDCs films on the curved surfaces for the first time by material extrusion. Through conformal algorithm development and process parameters exploration, different patterns on curved surfaces were realized. Subsequently, a conformal thin film temperature sensor (CTFTS) was fabricated on an alumina cylinder and tested at a high temperature of 800 °C. The results showed that the repeatability of multi-cycles was excellent and the resistance change rate was less than 1 % for half an hour of holding at 400 °C, 600 °C, and 800 °C. Given the high performance of the CTFTS on curved surfaces and the surface compatibility, CTFTS was fabricated conformally on a silicon nitride ceramic bearing and an alumina ceramic bolt, respectively. In the flame test and the rotation test, the CTFTS could detect in situ temperature in real-time with a response better than the commercial thermocouple. Therefore, the PDCs thin film conformal fabrication technique in this study is a highly promising approach for bringing PDCs films to practical applications, as well as a reference for multi-material conformal 3D printing.