Hosseini, SaharTorres, Juan F.Harzallah, RidhaLeclercq, ChristopheOuhib, FaridTricoli, AntonioLipiński, WojciechCoventry, Joe2026-07-032026-07-030094-243XORCID:/0000-0003-4020-3980/work/219172106ORCID:/0000-0002-3054-8638/work/219172775ORCID:/0000-0003-3701-3975/work/219178395https://hdl.handle.net/1885/733812322The long-term thermal stability of the silicon-based coating CoteRill®750 was examined via isothermal and thermal cycling aging tests. The coating was aged isothermally at three different temperatures of 800, 850, and 900℃, for 2000 or 3000 hours, and its optical durability compared with Pyromark 2500. CoteRill®750 has a higher absorptance and better optical and mechanical durability during the aging compared to Pyromark, e.g. no signs of failure were observed for CoteRill®750 after aging, while Pyromark 2500 mechanically failed at 900℃. Based on a figure of merit that accounts for both sunlight absorption and thermal emission at a representative temperature, the results show 1% better performance for CoteRill®750 than Pyromark 2500 (after aging at 800℃ for 2000 hours). Two different thermal cycling tests were carried out – a cycle and hold, and a rapid cycling test – and both indicated better solar-weighted absorptance for CoteRill®750 than Pyromark 2500. The coating can be applied at a large scale using the same spraying method as for Pyromark 2500. Therefore, with superior optical performance and a simple application method, CoteRill®750 is positioned to compete with Pyromark 2500 as the reference absorber coating for high-temperature CSP receivers.This research was funded by the Australian Government through the Australian Research Council (ARC) Linkage Project LP170101239 and the Australian Solar Thermal Research Institute (ASTRI). The authors also acknowledge the facilities and the scientific and technical assistance of Microscopy Australia at the Centre for Advanced Microscopy, Australian National University, a facility that is funded by the University and the Federal Government.enPublisher Copyright: © 2023 American Institute of Physics Inc.. All rights reserved.2023-10-0610.1063/5.014850285177555487