The Study And Preparation Of Cordierite Glass-ceramics

MgO-Al2O3 -SiO2 cordierite glass-ceramics were prepared by sintering method in this paper. In order to decrease the cost of the product, the industrial raw materials alumina , talcum, kaolin were used to replace the high pure Al2O3, MgO and SiO2 in this research, and some TiO2 was also added to improve the performance.The crystallization of the stoichiometric cordierite was studied by using TG-DTA and XRD. The results showed that stoichiometric cordierite glass powder could nucleate and crystallize by means of the surface of the powder. The primary phase of sample was -cordierite and the final phase was -cordierite. These revealed that it's possible to prepare the cordierite glass-ceramics using the industrial raw materials. However, it's difficult to sinter the stoichiometric cordierite. In order to improve the sintering character, it's indispensable to change the composition of the basic glass.The optimal content of TiO2 was studied by the test of performances and microstructure of samples. The results showed that the properties were of the optimum when adding 5% TiO2 in glass-ceramics.The optimal processing parameters of the non-stoichiometric cordierite glass-ceramics were also studied by the test of performances and microstrcture of samples. The results proved that the optimal nucleation temperature is 780 C, nucleation time 2h, crystallization time 2h, and heating rate 3 C/min.The crystallization of the non-stoichiometric cordierite was studied by XRD. The results showed that the first phase of sample is u-cordierite and the final phases are a-cordierite, forsterite, MAT and rutile .The change of group in cordierite samples were studied by FIIR. The results showed that only the change of Silicon-oxygen chain was detected in the samples without TiO2. Quadridentate Titanium was detected in the samples with 5% TiO2 at the low temperature. However, absorption peak of sexadentate Titanium was not detected at the high temperature, it might not be detected by IR Spectrabecause of too little Titanium phase.The crystallization kinetics of cordierite glass-ceramics and the effect of nucleation agent on the crystallization kinetics parameters were studied by TG-DTA. The results showed that the crystallization activation energies and the crystallization temperature reduced, and the reaction rate constant increased by adding 5% TiO2. It is showed the decline of the stability of the glass and the enhancement of the crystallization tendency.