The Process Research of the Amorphous SiO_2 Fibre-optical Perform Gel with SOL-GEL Method

In this paper,we researched the producing technology of SiO2 gel which adopt sol-gel process method prepared from the tetraethoxysilane as raw materials,and in which alcohol and water as solvent,formylamine and hydrochloric acid as additives.The SiO2 gel microstructure,the chemistry bond and the phase structure were characterized by means of XRD(X-ray diffraction instrument),SEM(scanning electricity mirror) and XPS.The result showed that the gel SiO2 is an amorphous state,main element chemical compositions are Si and O.Study the influence of the additive and the heat treatment temperature process on the SiO2 preform.Experiment research indicated: the system was layered when the hydrochloric acid added relatively minor,with increasing of the hydrochloric acid amount the gel time become shorten,then turbidness appeared.Adding formylamine can reduce the tiny crack amount of gel effectively,the more the formylamine amounts,the less the gel transparency.In the process of heat treatment,when the temperature is high,the warming increase rapidly,and more tiny cracks and air cavities generated.Conclusion: the heat temperature of the Sol is 90℃,and the temperature of heat treatment of the gel is 110 ℃,the ratio of tetraethoxysilane: Alcohol: Water=1∶4∶8,adds the appropriate amount hydrochloric acid and formylamine,SiO2 gel can reach good transparency and synthetical performance.