In Situ Laser Fabrication of Polymer-Derived Ceramic Composite Thin-Film Sensors for Harsh Environments

Abstract

Polymer-derived ceramic (PDC) is considered an excellent sensing material for harsh environments such as aero-engines and nuclear reactors. However, there are many inherent limitations not only in pure PDC but also in its common fabrication method by furnace thermolysis. Therefore, this study proposes a novel method of rapid in situ fabrication of PDC composite thin-film sensors by laser pyrolysis. Using this method with different fillers, a sensitive PDC composite film layer with high-quality graphite can be obtained quickly, which is more flexible and efficient compared to the traditional furnace thermolysis. Furthermore, this study analyzes the reaction differences between laser pyrolysis and furnace thermolysis. The laser pyrolysis method principally produces β-SiC and enhances the graphitization of amorphous carbon, while the degree of graphitization by furnace thermolysis is low. In addition, it is capable of rapidly preparing an insulating PDC composite film, which still has a resistance of 5 MΩ at 600 °C. As a proof of this method, the PDC composite thin-film strain sensors are fabricated in situ on nickel alloys and aluminum oxide substrates, respectively. The sensor fabricated on the nickel alloy with a high gauge factor of over 100 can be used in high-temperature environments below 350 °C without the protection of an oxidation-resistant coating. In this way, the approach pioneers the in situ laser fabrication of functional PDC films for sensors, and it has great potential for the in situ sensing of complex curved surfaces in harsh environments.

Rapid Printing of High-Temperature Polymer-Derived Ceramic Composite Thin-Film Thermistor with Laser Pyrolysis

“…These laser processing parameters can be referred to in the literature. 13 Finally, the AOL ink (PSN2/B/TiB 2 ) is written on the surface of the SL depending on the designed path (video of manufacturing details in associated content).…”

“…The laser pyrolysis principle and the laser parameters (laser energy density of 100 J/cm 2 ) are derived from the literature. 13 Although there are some differences in the components, the SL shows evident characteristic graphitic peaks D (1350 cm −1 ) and G peaks (1580 cm −1 ) and faint 2D peaks (2700 cm −1 ) by Raman analysis in Figure 3a, indicating that the amorphous carbon in the SL undergoes graphitization transformation under the laser scanning. Also, the X-ray diffraction (XRD) analysis Figure 3b shows that the SL generates silicon and SiC, similar to those in the literature.…”

“…Also, the X-ray diffraction (XRD) analysis Figure 3b shows that the SL generates silicon and SiC, similar to those in the literature. 13 Laser pyrolysis achieves graphitization of free carbon with TiB 2 facilitating the formation of conductive networks in the SL. Therefore, the antioxidant performance of the SL is challenging to exceed 400 °C because TiB 2 and graphite oxidation occur at 400 °C, 29,34 and SiC oxidation temperature is within 500 °C.…”

“…27 Thus, laser techniques have great potential for fabricating PDC high-temperature functional films, but there are few related kinds of research. Our previous work 13 proposed a new method to fabricate high-temperature functional thin films by laser pyrolysis of PDC. However, the conductive sensitive thin films made from PDC can hardly withstand hightemperature oxidation.…”

Thin-Film Platinum Resistance Temperature Detector with a SiCN/Yttria-Stabilized Zirconia Protective Layer by Direct Ink Writing for High-Temperature Applications

“…Temperature monitoring of hot-end components in extreme environments is vital in the field of aircraft engines. − For example, rapid and accurate measurement of the real-time temperature of turbine blades or spindle bearings contributes to the structural optimization and early fault diagnosis of critical components . Traditional wire temperature detectors, embedded sensors, welded sensors, and noncontact optical sensors have difficulties producing nondestructive and in situ temperature measurements of operating parts such as rotary blades or bearings. − Thin-film temperature sensors with rapid response, small disturbance, and easy integration are desired for the temperature measurement of hot-end components in harsh environments. − Platinum (Pt), with its relatively high melting point (1773 °C) and excellent chemical inertness, is a viable material for use in high temperature sensing. , The most commonly used manufacturing techniques for Pt films are screen printing, electron lithography, and magnetron sputtering . Among these methods, screen printing technology provides a fabrication process with low cost, simple operation, and high efficiency, but it lacks the ability to print on curved substrates and has a limited pattern resolution. , Electron lithography and magnetron sputtering can finely control the line width and film thickness of Pt films, but they also have disadvantages such as complex processing, high cost, and difficulties in conformally coating nonplanar surfaces. , …”