Air-Stability Improvement of Solar Selective Absorbers Based on TiW–SiO₂ Cermet up to 800 °C

Abstract

A high-temperature air-stable solar selective absorber (SSA) based on TiW–SiO2 cermet is prepared by the co-sputtering method. The obtained SSA shows remarkable stability in spectrum, structure, and chemistry after air-annealing at 700 °C, demonstrating its resistance against air erosion at high temperature. Comparing with W-SiO2-based SSA, the addition of the Ti element is proved to be effective in enhancing the thermal stability of SSA. Nevertheless, as the temperature increases to 750 °C, perfectly round cavities appear and induce the deterioration of the coating. A phase transformation from α-W to β-W is found at the interface of TiW/HMVF (high metal volume fraction layer) during deposition. Consequently, the inverse phase transformation from β-W to α-W at above 750 °C results in small vacancies at the interface, being the incentive of cavity generation. Afterward, the violent morphological changes of oxidized TiW accelerate the cavities expansion. To enhance its tolerance ability of service temperature, a Cr barrier layer is introduced to prevent the diffusion of oxygen into the TiW layer. Therefore, the optimal SSA performs stably at 800 °C and the failure temperature is elevated to 850 °C, revealing that the air-stable TiW–SiO2-based SSA has outstanding potential in high-temperature photothermal conversion.

Solar Selective Absorber for Emerging Sustainable Applications

“…Yang et al prepared a high‐temperature stable SSA based on TiW–SiO 2 cermet by cosputtering method. [ 29 ] By adding Ti element, the as‐obtained SSAC shows remarkable stability in spectrum, structure, and chemistry after annealing at 700 °C in air (Figure 2b).…”

An Ultra-High Temperature Stable Solar Absorber Using the ZrC-Based Cermets

“…Yang et al utilized the TiW-SiO 2 as absorption layers to prepare SSACs on the quartz substrate. The experimental results showed that incorporating the second phase Ti could effectively improve the stability of the absorber (Yang et al, 2021). In addition, a series of binary alloys (WTa, WNi, TiC, etc) based selective absorbers were proposed and their stable operating temperatures were further enhanced (Cao et al, 2015a;Cao et al, 2015b;Wang et al, 2017;Wu et al, 2020).…”

Phase-transition materials derived photonic metamaterials for passively dynamic solar thermal and coldness harvesting

“…Leveraging recent progress in the field of radiative heat transfer and photonic control [26] , [30] , advancements in thermal photonic metamaterials are facilitating the evolution of passive solar heating and radiative cooling technologies. Spectrally selective solar absorbers, such as multi-layered metal-dielectric stacks [15] , [31] , cermets [32] , [33] , and plasmonic nanostructures [34] , [35] , have been validated with spectral manipulation achievements. The aforementioned surfaces through architecting structures of metals and dielectrics all involve challenging nanofabrication instruments [15] , [32] , [33] , [36] .…”