Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Multilayer coating with high absorption of solar energy

CermetMultilayer coatingSolar collectorsolar energySolar thermal systems


The aim of the present invention is to propose a coating and a relative cermet composite which at temperatures of around 350° C and in vacuum conditions (around 5·10-3 Pa) present a high solar energy absorption and a low thermal emissivity that are also stable over time. Such  coatings/composites are therefore, in terms of absorption, spectrally selective. Such coatings and materials are suitable for being used in systems converting solar light into thermal and/or electric energy.

Technical features

The invention concerns a multilayer coating with high absorption of solar energy and with low thermal emissivity that comprises a first layer of molybdenum; a second layer essentially made up of TiO2 and niobium metal; and a third layer of SiO2. The invention moreover concerns a relative cermet composite essentially made up of TiO2 and niobium metal in which the concentration of niobium in the TiO2 corresponds to 27 – 34 at.%, preferably to 29.6 – 32.0 at.%, more preferably to 30.2 – 31.4 at.%, even more preferably to around 30.8 at.%. Furthermore, processes for producing the coating and the cermet composite, laminar or tubular materials coated with the coating and a use of the cermet composite are proposed. Compared to the known solutions, the present invention allows to obtain better performances which are also kept stable over time.

Possible Applications

  • Suitable for being used in solar thermal systems that make it possible to capture solar light, store it and use it in the various manners, in particular with the purpose of heating running water, replacing boilers or for producing electricity;
  • Applicable in planar and tubolar components,  in particular of solar systems.


  • High performance simultaneously in terms of high solar energy absorption and low thermal emissivity;
  • Stable performance over time.