Preparation Of Zirconia Fibers Via Sol-Gel Method

Zirconia fibers have been prepared via non-hydrolytic sol-gel method(NHSG)creatively using anhydrous zirconium chloride as zirconium source,ethanol as oxygen donor,yttrium as stabilizer,dibasic ester(DBE)as solvent.The phase transition during heat treatment of gel,effects of the spinning aid introduction,the types and amount of spinning aid,the precursor concentration,the rotary evaporator temperature and time on the spinnability of sol and the morphology of samples-were studied by means of DTA-TG,XRD,TEM,FE-SEM,FT-IR,viscometer and so on.The study shows the following results.Tetragonal zirconia phase forms at 400 ?,the formation of Y-O-Zr bond in the gel is the key to low-temperature synthesis of tetragonal zirconia.Sol particles without spinning aid or spinnability are monodispersive.The introduction of appropriate amount spinning aid makes colloidal particles grow along the polymer chain to form linear particles and the sol to be spinnable.Compared with the polyester resin with relative low aging temperature,ethoxyline with a higher aging temperature can make sol to be more spinnable.However,sol with overdosed ethoxyline is also unspinnable.-The spinnability of the sol with the viscosity of 52 Pa·s is the best when the spinning aid amount 5 wt.%(relative to the mass of zirconium oxychloride),the precursor concentration is 2 mol/L,rotary evaporator temperature is 120? and rotary evaporation time is 1 h.The surface of obtained fiber is smooth without cracks,its diameter is 8?10 ?m,and the aspect ratio of it is 65.On the basis of the investigation above,zirconia fibers have also been prepared via hydrolytic sol-gel(HSG)method using zirconium oxychloride as zirconium source and yttria as stabilizer.The phase transition of gel during the heat treatment process,the effects of solvent type,adding acetic acid and acetyl acetone,the introduction of spinning aid,the type and amount of spinning aid,the adding of zirconia xerogel powders,the introduction of reflux process on the spinnability of sol and the morphology of samples have been investigated.The results show that zirconia phase began to form when the gel heated at 500?.The spinnability of sol prepared with deionized water as solvent is better than that prepared with ethanol or 1,4-butanediol.Sol particles without spinning aid or spinnability are monodispersive.The spinnability of sol with PVP as spinning aid is better than that prepared with PEG or PVA as spinning aid.The spinnability of sols can be better by adding acetic acid and acetyl acetone as complexing agent and chelating agent.However,their corresponding fibers are cracking.The introduction of reflux process of zirconium oxychloride solution at 100? can improve the spinnability of sol and the quality of fibers.Proper amount of zirconia xerogel powders can increase the density of fibers.The spinnability of the sol with the viscosity of 45 Pa·s is the best when the amount of PVP and zirconia xerogel powders are 7 wt.%and 6 wt.%,respectively.The diameter of obtained fibers is 5?10?m,the aspect ratio of them can be 150,their surface is smooth and without crack.