Solar selective absorber coating for high service temperatures, produced by plasma sputtering

Michael Lanxner; Zvi Elgat

doi:10.1117/12.20448

1 August 1990 Solar selective absorber coating for high service temperatures, produced by plasma sputtering

Michael Lanxner, Zvi Elgat

Proceedings Volume 1272, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion IX; (1990) https://doi.org/10.1117/12.20448
Event: The International Congress on Optical Science and Engineering, 1990, The Hague, Netherlands

Abstract

Spectrally selective absorber coatings, deposited on engineering material substrates such as stainless steel, have been developed for service as efficient solar photothermal energy converters. The selective solar absorber is based on a multilayer of thin films, produced by sputtering. The main solar absorber is a metal/ceramic (cermet) composite, such as, Mo/Al2th or Mo/Si02, with a graded metal concentration. Such a cermet layer, strongly absorbs radiation over most of the range of the solar spectrum but is transparent to longer wavelength radiation. The cermet layer is deposited on a highly reflecting infrared metal layer. Two more layers were added: An AhO diffusion barrier layer which is deposited first on the substrate and an AI2O or a Si02 antireflection layer which is deposited on the top of the cermet film. In order to better understand the spectral reflectivity of the multilayered selective coating, a procedure for the calculation of the optical properties was developed. After the R&D development phase was successfully completed, a full scale production coating machine was constructed. The production machine is a linear in line coater. The selective coating is deposited on stainless steel tubes, translating in the coating machine while rotating about their axes, along their axial direction. Measurements of reflectance, solar absorptivity, a, thermal emissivity, C, and high temperature durability, are all parts of the quality control routine. The results show values of a in the range 0.96 - 0.98. The thermal emissivity at 350CC is in the range 0.16 - 0.18. Thermal durability tests, show no degradation of the coating when subjected to up to 65O in vacuum for one month and when passed through a temperature cycling test which includes 1200 cycles between temperatures of 150CC and 450CCfor a period of two months.

Citation Download Citation

Michael Lanxner and Zvi Elgat "Solar selective absorber coating for high service temperatures, produced by plasma sputtering", Proc. SPIE 1272, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion IX, (1 August 1990); https://doi.org/10.1117/12.20448

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