Fe₂O₃ films on stainless steel for solar absorbers

This paper reviews solar-selective coatings for concentrating solar power (CSP) applications. CSP systems require direct sunlight and solar tracking and utilize solar absorbers to convert sunlight to thermal electric power. Because this system receives direct sunlight which operating temperatures higher than 600 °C, heat-resistance new materials are needed to cope with. This paper presents a simple and low-cost process for depositing the high-temperature solar absorber. The high selective absorbing Fe₂O₃ films deposited on stainless steel (SS304) substrates to be absorbers by high thermal process at 850-1050 °C. The crystalline structure, surface microstructure and optic properties of the films were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV/visible spectroscopy (UV-vis-NIR Spectrophotometer, 0.25-2.5 μm). Optimal Fe₂O₃ films on SS304 substrates at (900-1000 °C) displayed high absorptivity (α) (0.909-0.922) and their emittance values(ε) are relatively low (0.18-0.38). This study proved the possibility of preparing high-temperature solar selective absorbing coatings with high solar absorptance and low emittance by using a simple thermal oxidation process. Those films have very good prospects for solar absorber because of simple process, low-cost, large-area and good performance.