Mechanism And Preparation Of Cordierite Powder Synthesized By Microemulsion-Sol Gel Technique

In this research, the cordierite nano powdes were prepared by sol-emulsion-gel method through doping magnesium nitratein,aluminium nitrate and TEOS in sol system which was solubilized in TritonX-100/n-hexanol/cyclohexane. The pseudo ternary phase diagram of sol/TritonX-100/n-hexanol/cyclohexane was build and plotted.The optimal technological parameters effects on phase behavior of W/O emulsion, quality of gel and gel time were confirmed. The particle size distribution of nano-powders and the sintering character, sintering character, Crystallization properties, microstructure and dielectrical property of samples derived from the powders were also studied. The cordierite powders derived from sol-emulsion-gel method were examined for Tape-casting process.Using TritonX-100 as surfactant together with n-hexanol as co-surfactant and cyclohexane as oil phase could dissolve more magnesium nitrate and aluminium nitrate, and a wider W/O micro-emulsion region could be obtained than others at 45℃. Results showed that concentration of precursor solution, pH value and ratio of [H2O]/[Si] was 1.5mol/L,5 and 4.5 respectively, then the gelation time was optimal (0.5h) and the abtained material could be qualified. The cordierite powder derived from sol-emulsion-gel method is so fine that its size reaches around 75nm and is well dispersed and the sintered sample derived from this powders could be sintered at 900℃to be cordierite ceramics with low dielectric constant and dielectric loss (ε<4,tgδ<0.001;1GHz). The dried green could be sintered at 900℃to be cordierite ceramics with the microstructure of a-cordierite which endow with sintered samples high mechanical property and excellent dielectric performance. So it could satisfy dielectric material's needs used for high frequency MLCIs.