Deposition & Characterization of TiAlON & TiMoAlON Solar Absorber Coatings for High Temperature Photothermal Applications Prepared by PEM Controlled Dual-Gas Reactive Magnetron Sputtering

Abstract:

A novel Plasma Emission Monitoring (PEM) controlled N2-O2 dual gas reactive dcMS method is proposed for deopsiting TiAlON and TiMoAlON solar absorber coatings. Working in a 'cheated' feedback mode, the PEM controller ensures smooth & precise control of O/N ratio in obtained oxy-nitrides without occuring of serious target poisoning. The coatings have three functional layers including the infrared reflector, the absorbing layer, and the antireflection layer. The absorbing layers of the two kinds of coatings are both designed to have a gradually change Al and/or O content. However, the TiAlON coatings have a single TiAlON absorber layer while the TiMoAlON have a tandem absorber composed of a Mo doped TiAlN layer and a Mo doped TiAlON layer. Single-crystal silicon chips and glass slides are used as substrates to deposit the coatings and to characterize the photothermal conversion properties and thermal stability of the coatings by using SEM, UV-visible-near infrared photospectrometer, and solar spectrum emissiometer. The experimtal results show that the tandem TiMoAlON coating exhibits superior theraml stability up to 550oC. After annealing in air at 500oC for 8hrs, it exhibits higher absorptance than as-deposited status. The annealed TiMoAlON coating has a broad absorbing peak covering 400-800nm, which is beneficial to collect the majority energy in solar radiation. Due to its higher absorptivity and lower normal emissivity than the TiAlON coatings, the TiMoAlON coating yields a high solar selectivity (α/ε≈19) at room temperature. However, at 500oC, its ε value increases from 0.05 to about 0.25 which might attribute to its excessive thicknesses of the sublayers. The above results demonstrate that the proposed method is a convenient way for preparing high performance oxy-nitride solar absorber coatings which are suitable for non-vacuum high temperature photothermal applications.

• Periodical: Advanced Materials Research (Volumes 538-541)
• Pages: 344-349
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.538-541.344
• Online since: June 2012
• Authors: Hai Bin Geng*, Tao Wu, Cheng Wei Ma
• Keywords: Dual-Gas Reactive Magnetron Sputtering, High Temperature Photothermal Conversion, Plasma Emission Monitoring, Solar Absorber Coating, Tandem Absorber

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