Spectrally selective thermal emitter based on HfO2/Mo multilayer film for high-temperature infrared stealth

By combining a reduction in emissivity and radiative heat dissipation, spectrally selective emitters can effectively conceal the thermal radiation of high-temperature objects, showcasing exceptional infrared stealth performance. Herein, with an ultrathin refractory molybdenum (Mo) film and transition metal oxide hafnium oxide (HfO2) film, a HfO2/Mo multilayer selective emitter with remarkable spectral performance and thermal stability is proposed for high-temperature infrared stealth. The emissivity is 0.29 within the 3 - 5 mu m detection waveband and 0.81 within the 5 - 8 mu m non-detection waveband, showing a pronounced spectral selectivity. Under vacuum conditions, the selective emitter maintains its spectral selectivity even at temperatures up to 700 degrees C. However, when exposed to air at temperatures of 300 degrees C or higher, the spectral selectivity of the selective emitter diminishes due to oxidation of the Mo film and formation of hafnium molybdate (HfMo2O8). The analysis of failure mechanisms holds significant guiding implications for the future advancement of selective emitters based on ultra-thin metals. Numerical simulations demonstrate that compared to the traditional low-emissivity emitter, HfO2/Mo selective emitters have lower physical temperature and radiation temperature, resulting in better infrared stealth performance. The proposed multilayer film features a simple planar structure without requiring complex manufacturing processes, enabling scalability for mass production purposes. The spectral selectivity and thermal stability of this emitter make it suitable for applications involving infrared stealth in high-temperature components of spacecraft.