Development of high infrared emissivity porous ceramic coating using pre-synthesized flower-like CeO2 powder for high temperature applications

Band gap and oxygen vacancy engineering of honeycomb‐like CuFe2O4 spinels toward enhanced high infrared emissivity

“…Figure 7D-F illustrates the surface macroscopic digital photographs, microstructures, and cross sections of the coatings after thermal cycling. As expected, the coating has no cracks, peeling, or obvious distortion even after 15 thermal cycles at a high temperature of 800 • C (Figure 7D,E), which is even better than several previous reports, 3,22 suggesting its enormous applications in the coating field. The cross-section image visualizes that the coating is merely widened by about 8 µm after thermal cycling (Figure 7F).…”

“…The macroscopic images, top‐view morphology, and cross‐sectional microstructure of the primary CNFO‐15 coating are presented in Figure 7A–C, respectively. Apparently, the prepared CNFO‐15 coating exhibits a uniform and flat surface with numerous pores (Figure 7A,B), which is beneficial for strengthening the infrared absorption of the coating and consequently improving its infrared emissivity 22 . Hence, a uniform coating with a thickness of approximately 133 µm was prepared (Figure 7C).…”

“…Apparently, the prepared CNFO-15 coating exhibits a uniform and flat surface with numerous pores (Figure 7A,B), which is beneficial for strengthening the infrared absorption of the coating and consequently improving its infrared emissivity. 22 Hence, a uniform coating with a thickness of approximately 133 µm was prepared (Figure 7C). Moreover, no fractures are found at the coating-substrate interface, indicating an excellent interface bonding between the coating and the substrate.…”

“…21 As a result, the majority of the infrared radiation reaching the coating surface can be effectively absorbed through the pores when substantial pores exist inside the filler particles, thus facilitating excellent infrared radiation performance. 22 Moreover, the pores can also counteract the volume expansion of the coating and release the high interfacial stresses between the coating and the substrate, preventing the coating from cracking during preparation and application. 23 With the above considerations, in this work, Ni-doped spinel CFO (i.e., Cu 1−x Ni x Fe 2 O 4 , x = 0, 0.05, 0.1, 0.15, and 0.2) honeycomb frameworks were successfully synthesized by the scalable sol-gel strategy and subsequent annealing treatment and denoted as CNFO-0, CNFO-5, CNFO-10, CNFO-15, and CNFO-20, respectively, for convenience.…”

“…According to Kirchhoff's rule, the infrared emissivity and absorption rates are of equal significance for an object under thermal equilibrium conditions 21 . As a result, the majority of the infrared radiation reaching the coating surface can be effectively absorbed through the pores when substantial pores exist inside the filler particles, thus facilitating excellent infrared radiation performance 22 . Moreover, the pores can also counteract the volume expansion of the coating and release the high interfacial stresses between the coating and the substrate, preventing the coating from cracking during preparation and application 23 …”