Study On Controlling Congregation Of ZrSiO₄ Nano-powder

Zircon powder has been synthesized at low temperature via non-hydrolytic sol-gel route,using zirconium tetrachloride and tetraethoxysilane as precursors,lithium fluoride as mineralizer in this paper.Based on the successful synthesis of zircon at 700 ?,the influencing factors on the synthesis and dispersion of zircon powder have been discussed by means of DTA-TG,XRD and TEM,including the precursor concentration,surfactants species and dosage,solvents kinds and the drying methods.It is the first time to introduce salts as dispersion medium in the process of preparing powder by the non-hydrolytic sol-gel,and the effects of salts on the synthesis and dispersion of zircon nano-powder are investigated.The influences of the precalcining temperature of dried xerogel powder,the introducing way,kinds and amount of salts,the species,amount and component of multiple salts have been studied.The results show that the precursor concentration has little influence on the synthesis of zircon,but the lower precursor concentration is favorable to the dispersion of zircon powder;solvents have obvious differences on the dispersion of zircon.Ethanol has the best dispersion effect among all solvents,and next comes dichloromethane.But propanol,isopropanol and N,N-dimethylformamide have worse dispersion effect compared with ethanol and dichloromethane,and affects the synthesis of zircon directly.Different kinds of surfactants have obvious influence on the synthesis of zircon,the according sequence is listed as the following:PEG1000>anionic surfactant(SDS)>cationic surfactant(HTAB).The 3%PEG1000 is favorable to the synthesis and dispersion of zircon.It can't synthesize zircon when using microwave drying or infrared drying due to the short time,while it have little influence on the systhesis and dispersion of zircon when using ordinary drying,distillation drying and vacuum drying.The addition of salts,which was mixed directly with the gel calcined at 530?,resulted in better zircon synthesis and powder dispersion.The kinds of single salt have little effect on the synthesis and dispersion of zircon,but the increasing of the dosage could restraint the formation of zircon.The best mole ratio of the salt/Zr is 3.Compared with the single salt,the multiple salts could improve the dispersion of powders more effectively.the according sequence is listed as the following:NaCl-KCl>NaCl-Na2S04>KCl-Na2S04.In NaCl-KCl binary system,it has little influence on the systhesis when n(NaCl/KCl)comes up to 2:1?1:2,and the optimum concentration of NaCl-KCl multiple salt is 25%.In NaCl-Na2SO4 binary system,the best synthesis and dispersion of zircon is achieved at n(NaCl/KCl)=2.