3D printing of thick film NTC thermistor from preceramic polymer composites for ultra-high temperature measurement

Abstract

Integrating thick/thin film sensors into component systems has emerged as a prevalent approach for monitoring in extreme environments. However, traditional vapor deposition methods face obstacles, including complex fabrication processes and the degradation of sensitive materials at extremely high temperatures. This work delineates the development of a polysilazane composite dual-layer thick-film Negative Temperature Coefficient (NTC) thermistor characterized by its suitability for extreme temperatures and robust bond strength achieved through an advanced near-net-shape printing methodology. High-temperature resistant La(Ca)CrO3/polysilazane films were printed as the sensitive layer, while a dense layer formed by Cr2O3/polysilazane was used as the protective layer. The bilayer structure resulted in a 2.5-fold increase in adhesion strength compared to the single-layer La(Ca)CrO3/polysilazane films. Experimental results indicate that the dual-layer thick-film NTC thermistor can be operated long-term at 1300 °C with a resistance drift rate of 0.9 %/h and survive short-term exposure to temperatures up to 1550 °C. As a proof of concept, this work applied 3D printing technology to fabricate a polysilazane composite dual-layer thick-film NTC thermistor on the surface of turbine blades and demonstrated its functionality under flame impingement at nearly 1300 °C. Such flexible 3D printing techniques pave the way for a new paradigm in manufacturing sensors capable of withstanding ultra-high temperatures.