High-temperature Concentrating Solar Thermal (CST) receivers are typically painted with a black paint, known as an absorption coating. The most commonly used paint is a proprietary product called Pyromark 2500. Despite its relatively common use, only a small quantity of research has been conducted on the aging and degradation processes of Pyromark 2500 in solar receiver applications. Observations from the field indicate that Pyromark does suffer significant performance reduction within a relatively short period of us, and experimental studies have corroborated this.
While a significant quantity of research has been conducted investigating the aging of Pyromark at constant elevated temperatures, these conditions somewhat unrealistic. In practise, operational receivers are subjected to frequent thermal cycling due to not only the day/night cycle, but also transient cloud cover. In addition, the receivers are subject to very high solar fluxes, in excess of 1 MW/m2. Despite the fact that the coatings are known to experience these fluctuating conditions, few studies have investigated the aging of Pyromark 2500 under thermal and flux cycling conditions.
In this project, the aim is to test metallic samples with absorber coatings in the ANU's high flux solar simulator. Because the simulator can only deliver a constant high flux, part of the project will be to design and construct an experimental apparatus that allows the samples to be cycled in and out of the high flux region. Sample cooling may also be necessary. Optical measurements of the samples will be taken before and at different stages during the accelerated aging process. Results will be compared to isothermal aging and thermal-cycling aging tests done previously at ANU to gauge the additional effect of high-flux on the aging process.