Al Doped Zno Transparent and Heat Insulation Coatings
|School||South China University of Technology|
|Keywords||Al Doped Nano ZnO Co-precipitation Azeotropic Distillation Dispersion Stability Heat Insulation Coatings|
Nano ZnO compounds are the most conventional transparent conductive oxides. It shows special applications in many fields, such as electron, photology, biology, medicine, coating et al. When doped with Al element, it has a high transmittance in visible area and high reflectivity in infrared region, so it is an ideal transparent and heat-insulating material. The preparation of transparent and heat insulating coatings made from nano-ZAO can solve the heat insulating performance of glasses. In addition, it has advantages like low cost and a simplified production process. So this kind of coating has very high practical application values and wide market prospects.Co-precipitation and azeotropic distillation process was used to fabricate ZAO powders, Zn(NO3)2 and Al(NO3)3 used as starting materials, NH3·H2O as precipitation agent, polyethylene glycol 2000 as dispersant. After that, the ZAO colloidal dispersions were made by dispersing the ZAO powder in distilled water with dispersants including SHMP, SDBS and PAA. At last transparent and heat insulating coating was prepared by adding acrylic emulsion film-forming agent to aqueous slurry of nano ZAO.XRD, TG-DSC, SEM were used to characterize crystal structure and catalytic property of ZAO nano powders; the morphology and particle size of the ZAO particles were observed by TEM and Malvern particle size analyzer; optical properties of prepared coatings were characterized by using UV–vis–NIR spectrophotometer; the heat insulation performance was analyzed by heat-shielding performance detector.The XRD patterns of ZAO powder showed it had a single phase with wurtzite structure. No alumina was detected in the sintered samples. From the TEM, Malvern particle size analyzer, it was obvious that the co-precipitate particles were all nano-sized (between 20 to 80 nm). They exhibited nearly spherical morphology and all particles were of uniform size and shape. The absorption spectrum of coatings showed the average transmittance in visible region was all over 88% and reflective 50% near infrared light. Heat insulation performance indicated that the coating had obvious heat insulating effects which had a temperature difference of 8-18 between the heat insulating coating and ordinary glass under iodine-tungsten lamp.