Preparation Of Inorganic Hollow Sphere Composites And Their Properties In Thermal Insulation Coatings

The development and application of building thermal insulation coating is an effective method to solve the problem of building energy conservation.In recent years,inorganic hollow sphere has become the research focus in the field of heat insulation coatings.In this paper,according to the thermal insulation mechanism,the inorganic hollow sphere composite material was designed and prepared,and the effect of reaction parameters on the morphology and properties of the product was studied.Hollow glass microsphere/Si-Al aerogel composite powder was prepared by stirring and dipping method.The thermal insulation performance and solar reflectance of the composite powder were studied.The solar reflectance of the obtained composite powder is about 60%,the thermal conductivity is lower than 0.04 W·m^-1·K^-1,and the lowest can be 0.034 W·m^-1·K^-1.The hollow glass microsphere/TiO₂ composites were prepared by hydrolysis precipitation method,and the surface of the hollow glass spheres were successfully coated with TiO₂ shells.TiO₂ shells have two kinds of morphology: nanosheets and nanoparticles.The morphology of the products under different reaction parameters were studied,and the growth mechanism of TiO₂ on the surface of hollow glass spheres was explored.The optical properties and thermal conductivity of the composite powder were tested,and the results showed that the visible-near-infrared reflectance of the HGM/TiO₂ composite hollow spheres was increased by more than 20% compared with the original hollow glass spheres,and the solar reflectance was up to 90%.The lowest thermal conductivity of composite powder could be 0.059 W·m^-1·K^-1.Nano-scale hollow SiO₂ microspheres were prepared by St(?)ber method,and the influence of reaction parameters on the morphology of products was investigated.The hollow SiO₂ spheres with different particle sizes were selected to test the solar reflectance and thermal conductivity.The results showed that with the increase of the particle size,the solar reflectance increased in the near infrared band and the thermal conductivity decreased.The solar reflectance can reach more than 80%,and the thermal conductivity is between 0.050-0.054 W·m^-1·K^-1.SiO₂/TiO₂ composite hollow spheres were prepared by precipitation method with the hollow SiO₂ microspheres as raw materials,and the optical reflection and thermal conductivity of the hollow spheres were investigated.The solar reflectance of SiO₂/TiO₂ hollow spheres is more than 90%in the visible-near infrared band and more than 95% in the visible band.The thermal conductivity is similar to that of hollow SiO₂ microspheres,which is between 0.050-0.052 W·m^-1·K^-1.Using the hollow glass microspheres and hollow SiO₂ microspheres as the functional filler of the thermal insulation coatings,using pure acrylic emulsion as the film-forming agent,the organic-inorganic composite coating materials were prepared by mechanical mixing method.The solar reflection and thermal conductivity of the coatings were investigated,and the insulation performance of the coatings was tested by using a self-made box device.Under the infrared light source,the coatings prepared with SiO₂/TiO₂ hollow spheres as the filler obtained the lowest external surface temperature,indicated that the coatings had good reflection performance.After being irradiated by infrared light source for 1h,the coating with hollow glass spheres/Si-Al aerogel as the functional filler had the largest temperature difference between the inner and outer surfaces,up to 11?.