Solar absorptive coating: a thermally stable spinel pigment based coating with inorganic binder for waterborne paint

Purpose The spectrally selective solar absorption paint is prepared from spinel-based mixed metal oxides with inorganic binder as a key component. Inorganic binder (furnace cement) is blended with mixed metal oxide pigment during synthesis. High temperature stability upto 1,100oC is achieved by the use of this modified coating system. The purpose of this paper is to work on solar selective coating synthesis, and application of a coating as a water-borne paint is the additive key feature that helps in reduction of solvent use. Design/methodology/approach The paint was formulated using water-based system, and the main component of colorant was made by mixed metal oxide-based spinel pigment and highly temperature stable inorganic binder. Findings The paint formed shows excellent absorptive power with low emittance even at high temperature. Optical and thermal properties were determined along with adhesion, abrasion and other properties. The solar absorptance for these samples were as = 0.93-0.95 with corresponding thermal emittance of eT = 0.096 (at room temperature) and 0.2-0.22 (at elevated temperature 100 degrees C). Originality/value The paint formed shows excellent absorptive power with low emittance even at high temperature. The paint can be applied in solar absorptive tower system. The obtained results indicated excellent thermal stability of prepared paint coatings. As inorganic binder was used, the paint has reduction in solvent use, and being water as a base, it is environment friendly, easy to apply and durable at high temperatures, as the binder itself is stable up to 1,500oC.