| In this paper, after a detailed review of the present research status of zirconia (ZrO2) porous gels and aerogels, the alkoxy-derived sol-gel process was used to synthesize ZrO2 porous gels and aerogels.Using Zirconium(IV) butoxide solution(Zr(OBu')4, TBOZ) and n-propanol zirconium (Zr(OPr')4, TPOZ) as raw materials, ZrO2 gels were prepared by the sol-gel method. The effect of nitric acid(HN03) content on the hydrolysis and condensation rate of zirconium alkoxides were systematically investigated:the gel time can be effectively controlled by the change of the nitrate content. Crystal stable ZrO2 gels were synthesized by doping yttrium oxide, calcium oxide and magnesia at different levels. when 8%mol of Y2O3 and 15%mol of CaO were doped, pure tetragonal and pure cubic ZrO2 can be synthesized respectively.The alkoxy-derived Sol-Gel progress accompanied by phase-separation were used to prepare multiscale porous Zirconia(ZrO2):using Zirconiu(IV) propoxide solution (Zr(OPr')4, TPOZ) as raw material, by addition of N-methylformamide(NFA) to control the gel process, while the phase-separation is induced by the incorporation of polyethylene oxide(PEO), ZrO2 gels with well-defined bicontinuous macropores and microstructured skeletons were prepared. The effect of nitric acid concentration, the amount of PEO added and post-heat treatment on the micro-porous gels structure were studied.High-temperature supercritical drying method was used to prepare zirconia aerogels:the effect of alcohol/zirconium ratio, post-heat treatment conditions on the pore size, surface area, density and linear shrinkage rate of the microstructure and properties of the ZrO2 aerogels were investigated. |
