Preparation Of Cs_0.33WO₃ Particles And Its Transparent Heat Insulation Coatings

Cs_0.33WO₃ particles was prepared by low temperature hydrothermal reaction using WCl6, CsOH·H2O and NaaWO4·2H2O, Cs2CO3 as raw materials respectively, and the advantages and disadvantages of the two processes were compared. The study results showed that the as-prepared Cs_0.33WO₃ powders has exectllent near infrared light shielding properties using Na2WO4·2H2O and CS2CO3 as raw materials, and the preparation process has the advantages of process simple, no pollution and low cost conducive to mass production.Using sodium tungstate and cesium carbonate as raw materials, cesium tungsten bronze (Cs_0.33WO₃) powders were synthesized by low temperature hydrothermal reaction with citric acid as the reducing agent. Effects of annealing in different atmosphere on the near-infrared shielding properties of Cs_0.33WO₃ were investigated. The microstructure of Cs_0.33WO₃ powders was characterized by X-ray diffraction, SEM and TEM. The Cs_0.33WO₃ films were prepared on glass using polyvinyl alcohol solution as film-forming agent, and the optical transmission properties of Cs_0.33WO₃ films were investigated. The results indicate that the near-infrared shielding ability of samples after annealed at 200 ℃ in the air atmosphere did not deteriorate apparently, but the 400 ℃-annealed samples in the air atmosphere showed apparent decrease of near-infrared shielding properties. Annealing in the carbon powder atmosphere had no apparent effects on the properties of Cs_0.33WO₃ particles. As for the N2 annealing, the 500 ℃-annealed samples showed best improved near-infrared shielding as well as high transparency in the visible light region.In order to achieve good dispersion of Cs_0.33WO₃ particles and improve their near-infrared （NIR） shielding efficiency, the influences of ball-milling and dispersant on the dispersion stability of Cs_0.33WO₃ particles and its near infrared shielding properties were investigated. The results indicated that adding appropriate dispersant after ball-milling was conducive to dispersion of Cs_0.33WO₃ powders. Polyvinyl alcohol and titanate coupling agent could improve dispersion stability of Cs_0.33WO₃ particles. Particularly, the as-prepared Cs_0.33WO₃ coatings prepared from colloidal dispersion solution using titanate coupling agent at pH=7 showed best visible light transmittance and near-infrared shielding properties.The influences of different film forming agents on the properties of transparent insulating coating were also studied. The Cs_0.33WO₃ coating was prepared by using polyvinyl alcohol （PVA）, polyvinyl butyral （PVB） and polyvinylpyrrolidone （PVP） as film forming agents, respectively. The results indicated that the coatings of PVA/Cs_0.33WO₃ and PVP/Cs_0.33WO₃ showed best visible light transmittance and near-infrared shielding properties, and PVP/Cs_0.33WO₃ coating showed excellent adhesion.