Influence of Flaky Aluminum Powder and SiO2 Aerogel Fillers on the Thermal Insulation Properties of Silica Sol/Styrene-acrylic Emulsion Double-layer Coatings
To enhance the thermal insulation properties of coatings,double-layer coatings were constructed.The coatings were prepared with silica sol and styrene-acrylic emulsion as the main and auxiliary film-forming compounds,respectively.The bottom and top coating contained SiO2 aerogel and flaky aluminum powder as their thermal insulation fillers,respectively.The behavior of flake aluminum powder and SiO2 aerogel thermal insulating fillers on the thermal insulating properties of double-layer coating was systematically investigated,and the related thermal insulating mechanisms were discussed.The results indicated that the optimal insulation effect was achieved with 4％aluminum powder addition,resulting in the insulation temperature difference of 9.1℃ compared with that of the blank board sample.For the SiO2 aerogel-based coating,the optimal addition for best thermal insulation was 4％-5％.The addition of flaky aluminum powder could render it with the reflection-type thermal insulation property,while the addition of SiO2 aerogel could render it with the barrier-type thermal insulation property.By combining the thermal insulation characteristics of both,a double-layer coating structure with dual mechanism thermal insulation properties was successfully constructed,with a thermal insulation temperature difference of 10.9℃,which was higher than the thermal insulation effect of a single coating.
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