Thermal emittance of Ag films deposited by magnetron sputtering

Abstract A series of Ag films were deposited on stainless steel by magnetron sputtering as an infrared reflective layer in solar selective absorbing coating, while their micro-morphologies and phase structure were characterized by SEM and XRD. The effects of different thickness, substrate roughness and deposition temperature on both spectrum reflectance and emittance are investigated. The minimum thermal emittance of 0.6% at 25 °C can be obtained with thickness of 120 nm and it is not affected by deposition temperature below 100 °C. The spectrum reflectance tends to decrease with an increase of the substrate roughness and deposition temperature. Depositing the TiAlONM/TiAlOND/AlON layer on the optimized Ag film, the emittance of the SSAC at 400 °C is only 5.8%, which meets the optical requirements for the IR-reflector.