Study On Preparation And Properties Of TiO₂/BiOCl Reflective Thermal Insulation Materials

Thermal insulation materials are a new type of functional materials developed in recent years. The development of thermal insulation materials is expected to enable the people to realize the dream of energy conservation while enjoying a comfortable life. Therefore, the development of insulation thermal materials, especially the reflective thermal insulation materials has attracted scientists both at home and abroad.This paper studies the impact on the near-infrared reflection properties by the sample composition, crystal type and morphology of the powder samples. In this paper we studied the optimize process to prepare the spherical titania by surfactant-aided sol-get methods, sheet bismuth oxide chlorine by precipitation and composite of TiO₂/BiOCl by solid-phase method through the Near-Infrared reflectance spectroscopy, respectively. In this paper, the three kinds of above-mentioned powders were also added into the water-based acrylic resin to make the coatings on the glasses. The results of the test indicated that the obtained coatings with a strong near-infrared blocking ability, is expected to become a near-infrared insulating coatings, has broad market prospects. Based on these studies, we have a number of meaningful conclusions, summarized as follows:Firstly, mono-disperse microspherical TiO₂ precursors with mean size of 800 nm were successfully synthesized by surfactant-aided sol-gel methods using a non-ionic surfactant TO8 as templates. Porous microspherical TiO₂ with the similar size can be gained by appropriate heating. And titania of different crystal type could be gained by different heating temperatures and time. The sample composition, crystalline state and morphology of the powder samples have great impact on the near-infrared reflection properties. Spherical titanium dioxide powders have strong reflection than the irregular morphology ones due to its high bulk density. Mesoporous titania microspheres having a super-low-density and pore structure processing superior reflective performance compared with non-porous microspheres. With the calcined temperatures increased, the mass fraction of rutile phase increased and the reflective properties of the products also increased due to the more closely of the crystal accumulation and higher refractive index. However, the microspheres could be reunion if the calcined temperature was too high, and the near-infrared properties also declined. Considering that, the optimize calcined temperatures and time was 800°C and 2 hours.Secondly, Bismuth oxide chloride sheet has a strong near-infrared reflectivity due to its higher refractive index. The properties of the reflectivity of bismuth oxide chlorine could be highly increased by modified the samples the commercial ones' surface through the precipitation method. The optimize processing was as follows: In 60°C water bath, controlling the pH value of 5, both the ammonia concentration and initial concentration of bismuth solution was controlled as 0.1mol/L, ammonia droplet acceleration was 3 ml/min while precipitation aging time was 1h, and treated it at the 600°C for 2 hours.Thirdly, TiO₂/BiOCl composite samples have strong reflectance in the range of 700 - 2500 nm due to synergies. When the composite synthesized by the molar ratio of TiO₂ and BiOCl was 1:1, grinding for 90 minutes and calcined at 600°C for 2 hours, the powder from the highest rate of near-infrared reflectance. Meanwhile the sample has strong UV absorption capacity, which is expected isolated from the infrared and UV energy as also. Add the appropriate amount of composites into the industry membrane, the reflectivity of the membrane could be enhanced by 200 %.Fourthly, add the appropriate amount of the three powders into the coatings with a few dispersing agent WS-211, can significantly reduce transmittance of the coatings in the near-infrared region, so as to achieve the purpose of cooling and energy-efficient.