Preparation And Properties Of A Lightweight High-strength Material Based On Hollow Glass Microspheres

In this paper, a lightweight high-strength material was fabricated using hollowglass microspheres (HGM) as the main material. The microspheres connected eachother directly and were not damaged. It takes advantage of the low thermalconductivity of the air to achieve lightweight and excellent thermal performances.Because the commercial HGM are often hydrophobic treated, conventionalwater-based oxide binder is difficult to wet the surface of HGM. Two methods weretried in this paper. The first method was to prepare the ethanol-water-based B2O3-SiO2and P2O5-SiO2sol. The sol could wet and bond HGM. The effects of sinteringtemperature, different ratio of B/Si and water/silicon on the performance of thespecimens were studied. The second method was to modify HGM surface byhydrofluoric acid corrosion, calcinations and acrylic acid grafting. An inorganicaluminum-chromium phosphate binder was used to bond the HGM, and the effects ofsintering temperature and the concentration of chromium-aluminum phosphatesolution on the performance of the specimens were studied.The results indicated that the HGM specimens bonded by borosilicate orphosphorosilicate glass possessed a better performance. The apparent density of thesespecimens was below0.48g/cm3and the compressive strength reached14.9MPa.Because the melting point of borosilicate glass was relatively low, the densification ofthe samples was a liquid phase reaction sintering process. The specimens H sintered at750°C possessed the best performances with apparent density of0.43g/cm3, apparentporosity of41%, thermal conductivity of0.1W/m·K and compressive strength of10MPa. The densification process of the specimens with phosphorosilicate glass, wasmainly carried out by the solid-phase reaction. With the increasing temperature, thesolid phase reaction accelerated, and as a result, the shrinkage of the samplesincreased. The enhanced densification increased the apparent density. The apparentporosity was affected by densification and performance of HGM, while densificationand porosity played significant roles on compressive strength of the specimens.The HF corrosion was most effective and the apparent density of the specimenswas0.4~0.5g/cm3, apparent porosity was30~40%and the compressive strengthreached13MPa.