Growth, characterization and performance evaluation of Ti/AlTiN/AlTiON/AlTiO high temperature spectrally selective coatings for solar thermal power applications

We describe the growth, characterization and performance evaluation of a multilayer solar selective coating useful for solar thermal power generation. The solar selective coating of the present work consists of Ti/chrome interlayer, two absorber layers of AlTiN and AlTiON, and an anti-reflection layer of AlTiO. All the layers have been deposited using reactive pulsed direct current sputtering of Ti and Al targets in Ar+N2, Ar+N2+O2 and Ar+O2 plasmas, respectively. A large number of analytical tools have been used to characterize the structural and optical properties of the absorber coating. The optimized coating exhibited an absorptance of 0.930 and an emittance of 0.16-0.17 on stainless steel substrates and an absorptance of 0.933 and an emittance of 0.07 on copper substrates. The absorber coating displayed improved adhesion, UV stability, corrosion resistance and thermal stability in air and vacuum up to 350 and 450 °C, respectively under cyclic heating condition for more than 1000 h.