Determination of the changes on the thermal and optical properties of selective solar absorber coatings induced by prolonged thermal treatment

Juan Daniel Macias, Dallely Melissa Herrera Zamora, Francisco Ivan Lizama Tzec, Gerko Oskam, Jose Bante Guerra, Oscar Eduardo Arés Muzio, Hernando Romero Paredes, Camilo Alberto Arancibia Bulnes, Victor Ramos Sánchez, Heidi Isabel Villafan Vidales, Juan Jose Alvarado Gil

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

High temperature ageing is frequently used in many technical application areas for the assessment of the thermal stability of materials; a high temperature treatment accelerates all kinds of processes, frequently performed to induce stabilization of the material. For solar absorber surfaces composed of small metal particles a high temperature treatment accelerates oxidation of the metal which in turn decreases mainly the optical properties of the coatings. Likewise changes of the surface due to machining, heat treatment, roughness and porosity can induce changes in effective thermal properties of the surface, which would affect cooling or heating process of the surface. In photothermal deflection spectroscopy (PDS) technique the sample absorbs optical radiation (pump laser) and heats the gas or liquid above the surface, the heat changes the refraction index of the fluid. A second low power laser beam is sent to probe the changes of the refraction index, in such a way that the photoinduced deviation of the probe beam are monitored using a position sensor detector. It has been shown that the beam deflection is strongly correlated to the optical and thermal properties of the materials, and it can provide important parameters as the optical absorption coefficient as well as the thermal diffusivity of the material. This non-contact technique can be particularly useful when analyzing materials in extreme conditions or when a methodology in which attachment of the sensors to the sample is not desirable or even possible. In this work, the changes of the thermal and optical properties of selective coatings exposed to a thermal treatment consisting in heating at 573 K for 200 hours, were studied using a combination of photothermal deflection spectroscopy (PDS) technique, UV/VIS/Near spectroscopy and FTIR. Samples consist of steel substrates coated with solar absorber coatings based in black cobalt and black nickel, deposited using electrochemical methods. The layer structure of black cobalt solar absorbers consisted in a bright nickel infrared reflective layer (thickness: 3.12 μm) covered with a black cobalt high solar absorbance thin film (thickness: 0.28 μm). In the same way, layer structure of black nickel solar absorbers consisted in a bright nickel infrared reflective layer (thickness: 3.12 μm) covered with a black nickel high solar absorbance thin film (thickness: 0.33 μm).

Original languageEnglish (US)
Title of host publicationSolarPACES 2017
Subtitle of host publicationInternational Conference on Concentrating Solar Power and Chemical Energy Systems
EditorsRodrigo Mancilla, Christoph Richter
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735417571
DOIs
StatePublished - Nov 8 2018
Externally publishedYes
Event23rd International Conference on Concentrating Solar Power and Chemical Energy Systems, SolarPACES 2017 - Santiago, Chile
Duration: Sep 26 2017Sep 29 2017

Publication series

NameAIP Conference Proceedings
Volume2033
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference23rd International Conference on Concentrating Solar Power and Chemical Energy Systems, SolarPACES 2017
Country/TerritoryChile
CitySantiago
Period9/26/179/29/17

ASJC Scopus subject areas

  • General Physics and Astronomy

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