Synthesis And Characterization Of Low Thermal Conductivity TiO₂ And SiO₂ Hollow Microspheres

Hollow microspheres particles with its unique hollow structure, and with thermal interfacial heat transfer of the gas/solid phases, can significantly improve the micro-nano powder of the thermal insulation. Hollow microspheres also can help alleviate the increasingly serious problems about the thermal insulation in building energy efficiency field. In this paper, we researched synthesis technology by template method about the low thermal conductivity of Ti O2, Si O2 and Ti O2/Si O2 composite hollow microspheres, and characterized the synthetic products.The results showed that, Synthesized anatase Ti O2 hollow microsphere, while grain size ranging from 400 nm to 700 nm, and shell thickness ranging from 25 nm to 100 nm, using carbon spheres activated by Sodium hydroxide solution as template, and tetrabutyl titanate as titanium source. The solar absorptance ratio of the powder is 0.119. The thermal conductivity of the powder/ epoxy resin compound reaches 0.0654W/(m·K), when the shell thickness under 70 nm.Synthesized amorphous Si O2 hollow microsphere, while grain size ranging from 300 nm to 400 nm, and shell thickness ranging from 15 nm to 50 nm, using polystyrene microsphere activated by polyvinylpyrrolidone as template, and Tetraethyl silicate as silicon source. The solar absorptance ratio of the powder is 0.116. The thermal conductivity of the powder/ epoxy resin compound reaches 0.1078W/(m·K), when the shell thickness under 20 nm.Synthesized Ti O2/Si O2 and Ti O2/glass microspheres composite hollow microspheres by hydrothermal reaction in 180℃ for 12 h, using two kind of template of Si O2 hollow microspheres synthesised in this paper and activated hollow glass microspheres, and tetrabutyl titanate as titanium source. The Ti O2 shell entire coveres, while using 0.5g Si O2 hollow particles and the amount of TBT range from 0.8 to 1.2ml. Activing the hollow glass microspheres template by dipping in KH550 or KH570 for 6h, the Ti O2 shell grows intact. The spectral reflectance of composite hollow microspheres improves from the Si O2 hollow particle, as the number of absorption peaks decreased, and the solar absorptance decreased. The thermal conductivity of the powder/ epoxy resin compound reaches 0.0635W/(m·K).