Characterization of Pyromark 2500 Paint for High-Temperature Solar Receivers

TLDR

Pyromark 2500 is a silicone‑based high‑temperature paint used on central receivers to boost solar absorptance. This study presents its radiative properties, aging behavior, and selective absorber efficiency as a baseline for comparison with emerging high‑temperature solar selective absorber coatings. The authors postulated that substrate effects may alter the coating’s crystal structure at elevated temperatures. Solar absorptance ranged from ~0.97 at near‑normal incidence to ~0.8 at 80°, while thermal emittance increased from ~0.8 at 100 °C to ~0.9 at 1000 °C; after aging above ~750 °C, absorptance dropped by several percentage points within days.

Abstract

Pyromark 2500 is a silicone-based high-temperature paint that has been used on central receivers to increase solar absorptance. The radiative properties, aging, and selective absorber efficiency of Pyromark 2500 are presented in this paper for use as a baseline for comparison to high-temperature solar selective absorber coatings currently being developed. The solar absorptance ranged from ∼0.97 at near-normal incidence angles to ∼0.8 at glancing (80°) incidence angles, and the thermal emittance ranged from ∼0.8 at 100 °C to ∼0.9 at 1000 °C. After thermal aging at temperatures of ∼750 °C or higher, the solar absorptance decreased by several percentage points within a few days. It was postulated that the substrate may have contributed to a change in the crystal structure of the original coating at elevated temperatures.