12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone
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Black Cr/α-Cr2O3 Nanoparticles Based Solar Absorbers: Growth Kinetic

Presented by Mr. Saleh KHAMLICH on 13 Jul 2011 from 12:15 to 12:30
Type: Oral Presentation
Session: CMPMS1
Track: Track A - Condensed Matter Physics and Material Science


<p>Black chromium-chromium (III) oxide cermet (Ceramic-Metal) nano-composites exhibit attractive solar absorbance characteristics. They are used widely as selective solar heat thermal collector nano-coatings. These black chromium-chromium (III) oxide selective solar absorbers are produced by various physical vapor deposition techniques such as DC and RF reactive sputtering, pulsed sputtering method, and e-beam and thermal evaporation techniques. This contribution reports on large surface coatings of black chromium-chromium (III) oxide cermet by using a novel cost effective physical-chemical method: the Aqueous Chemical Growth (ACG). More specifically, the present study addresses the growth mechanism of the uniform fine (in the range of micron to nano)-spherical particles of α-Cr2O3 using the ACG method at low temperature. The growth kinetic of the quasi-mono-dispersed spherical particles of chromium (III) oxide, α-Cr2O3, in aqueous solution was studied as a function of ageing time. The small fine spherical particles of α-Cr2O3 revealed by SEM micrographs suggests a growth mechanism based on the diffusion-limited Ostwald ripening process on the basis of LSW theory. The experimental data were analyzed in the frame of existing coarsening and particle growth mechanisms, i.e. Ostwald ripening. A good fits of the growth of α-Cr2O3 particles with d3 model confirms the growth mechanism to be mainly diffusion-controlled.Two major configurations have been considered initially: Cr black coated α-Cr2O3 nano-particles coatings/Cupper substrate and Cr black coated α-Cr2O3 nano-particles coatings/discontinuous ultra-thin Cr layer/Cupper substrate. The optimized configurations exhibit a low diffuse reflectance as well as low transmittance in the VIS-NIR spectrum sustaining therefore their high solar absorbance property.

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Room: Parthenon

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