EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Soiling of mirrors is one of the main reasons for the increase of maintenance costs in concentrated solar thermal power (CSP) generation (Bellman, 2020). Such a problem poses multiple challenges originating both from the surfaces' nature and their  interaction with their environment - such as desert dust - which previous approaches have failed to address fully. For this application the durability of the layers is critical hence techniques such as sputtering are needed that have shown a remarkable record in the mass scale production of tribological films. The proposed  solution takes advantage of the superhydrophilicity of sputtered thin films on the mirrors. As the mirror is the first component to interact with the sunlight in the energy harnessing process, its efficiency is critical to the system performance. Mirror reflectivity is one of several factors affecting the energy delivered by the solar field to the receiver, whilst the reduction of cleaning water consumption (Duvenhage, 2019) is another key factor that needs to be addressed. In this work, we study and develop stable superhydrophilic amorphous TiO2  coatings (Lee, 2017) deposited using magnetron sputtering, and we optimize the pre-deposition surface cleaning. We also perform superhydrophilicity measurements and other characterization techniques (SEM, EDS, XRD, Raman, AFM) gaining significant information on the structural and morphological properties of samples of various thickness'. Moreover, we demonstrate the augmentation of the superhydrophilicity and the stability of the deposited layer, whilst maintaining the mirrors' reflectivity.

Acknowledgment: Project Nano4CSP is supported under the umbrella of SOLAR-ERA.NET Cofund 2 by: GSRT (General Secretariat for Research and Development, Greece), RIF (Research and Innovation Foundation, Cyprus) and FFG (Austrian Research Promotion Agency). SOLAR-ERA.NET is supported by the European Commission within the EU Framework Programme for Research and Innovation HORIZON 2020 (Cofund ERA-NET Action, N° 786483)