S olution-chemical derived nickel–alumina coatings for thermal solar absorbers

A promising novel solution-chemistry method to fabricate spectrally selective solar absorber coatings has been investigated. The selectively absorbing film consists of nickel nano-particles embedded in a dielectric matrix of alumina. Ejecting a precursor solution of nickel and aluminum onto an aluminum substrate using a spin-coating technique followed by a heat-treatment, generated the solar absorber samples. Smooth and homogeneous films with a nickel content of 0 to 80 vol.% were produced. The optimal coating had a nickel content of 65%, a thickness of 0.1 mm and a particle size of |10 nm. The absorbing layer attained a normal solar absorptance, a , of 0.83 and a normal thermal emittance, ´ , of 0.03. sol therm Adding an anti-reflection layer on top of the first absorbing layer further enhanced the performance of the absorber. The optimum anti-reflection coated sample reached a solar absorptance of 0.93 and a thermal emittance of 0.04.  2003 Elsevier Ltd. All rights reserved.