Improvement of thermal stability in the solar selective absorbing Mo–Al2O3 coating

Mo–Al2O3 solar selective absorbing coating was deposited on stainless steel substrate by magnetron sputtering. The evaluation of high temperature stability indicates that the degradation of the optical properties is due to the diffusion and oxidation of single metal Mo in the ceramic Al2O3. Mo diffuses easily in Al2O3 layer and the interface between the double Mo–Al2O3 layers when aging temperature is above 400 °C, which was observed by SEM and AES with etching depth. The thermal stability was improved significantly when a denser Mo–Al2O3 layer was obtained by optimizing the deposition parameters.

► Solar selective absorbing coating of SS–(Fe2O3)/Mo–Al2O3 was fabricated by magnetron sputtering.
► Analysis of the thermal stability reveals that there exists serious interfacial compositional diffusion in the coating.
► Thermal stability greatly improved when a denser Mo–Al2O3 layer was obtained.