Molten salt-assisted synthesis of CuMn2O4 spinels and their enhanced Infrared Radiation properties

CuMn 2 O 4 (CMO) spinels show great potentiallity in the radiation heat transfer of industrial furnaces and thermal protection of hypersonic vechicles due to its unique crystal structure and excellent infrared radiative performance at short and middle wavebands. However, it still remains a considerable challenge to prepare high-infrared-emissivity CMO spinels at low temperatures. Herein, CMO spinels are successfully prepared via a facile molten salt-assisted method at a reduced temperatures lower than 900 °C. The synthetic parameters of CMO including the mass ratio of the reactants, i. e. CuO and MnO 2 , to the eutectic salt NaCl-KCl and annealing temperature are investigated in detail. The optimium CMO-850 sample exhibits the highest infrared emissivity of 0.907 in the 3 – 5 μm band at 600 °C, which is related to the optimal crystalization, smaller band gap, as well as higher oxygen vacancy concentration (34.33%). Moreover, the CMO-850 based coating demonstrates excellent interfacial bonding, thermal shock resistance, and infrared radiation properties, and achieves high infrared radiative values of 0.919 (600 °C) at 3 – 5 μm and 0.923 (300 °C) at 8 – 14 μm, respectively. Our work provides an essential guidance for future design of advanced infrared-emissive materials toward energy protection, heat dissipation, and eve radiative cooling fields.