pH值和烧结温度对溶胶-凝胶方法制备堇青石粉体性能的影响

Effect of pH Value and Sintering Temperature on the Properties of Cordierite Powders Synthesized by Sol-gel Method

以正硅酸乙酯、镁盐和铝盐为原料,通过溶胶-凝胶法合成堇青石粉体,通过TGA-DSC、XRD等测试手段,讨论了反应体系pH值和烧结温度对产物晶相和性能的影响。结果表明:体系pH值为2的试样,在900℃时,出现尖晶石相和假蓝宝石相,升温到1000℃的时候,开始有μ-堇青石出现,在1250℃煅烧2 h几乎全部转化为α-堇青石,体系pH为7的试样,在900℃时,有μ-堇青石形成,经1250℃煅烧后,β-堇青石相增多,μ-堇青石相和镁铝尖晶石相消失,合成粉体的平均晶粒尺寸随pH值增加呈先减小后增加的趋势,在不同温度煅烧下的压片试样,体系pH值为7的试样收缩最大。

Cordierite powers was synthesized by sol-gel method from TEOS and magnesium and aluminum salts,The effects of solution pH value and sintering temperature on the crystal structure and properties of the cordierite powders were discussed by TGA-DSC and XRD measurements. The results show that solution pH value was 2,that phase of magnesia alumina spinel and sapphirine occured at 900 ℃,the μ-cordierite formation started at about 1000 ℃, μ-cordierite to α-cordierite transformation was fully completed at 1250 ℃,when solution pH value was 7,the phase of μ-cordierite occured at 900 ℃,β-cordierite phase increased at 1250 ℃ μ-cordierite phase and magnesia alumina spinel phase disappeared.The average particle size of cordierite powders decreased firstly and then increases as the pH values increasing. When solution pH values was 7,the linear shrinkage rate of the samples was the biggest of all.