Synthesis and properties of green/sky blue high near infrared reflection coatings based on Mg2.4-xMxTiO4.4+δ (M = Cr/Co) inorganic pigments

To alleviate the urban heat island effect, reduce building energy consumption and improve the living environment for residents, the development of highly reflective pigments and coatings is of great significance for sustainable development. In this study, Mg 2.4- x Cr x TiO 4.4+δ (0.1 ≤ x ≤ 0.3) and Mg 2.4- x Co x TiO 4.4 (0.1 ≤ x ≤ 0.4) pigments with intense green/sky blue colors were successfully synthesized through solid state method. The crystal structure, color development mechanism and optical properties of as-synthesized samples are analyzed. The as-prepared pigments demonstrate excellent NIR reflectance with the highest solar reflectance up to 83%. Furthermore, the color coatings with high NIR solar reflectance were successfully prepared by mixing the pigments with acrylic resin. A solar reflectance of 69.81% is achieved among the green/blue coatings. The thermal shielding effect of the coatings in practical applications was tested through chamber simulation experiments. The test temperature of the prepared coating was 8.8 ℃ lower than that of the blank stainless steel plate after radiating with a 250   W infrared lamp for 30   minutes, which proved its good heat insulation performance. Through pickling and alkali washing experiments, the color coordinates of the coatings are very stable, indicating the excellent acid-base resistance in the practical applications.