摘要: The kaolinite-mullite reaction series of eight kaolin samples have been studied with XRD, IR, DTA and MAS NMR spectra. The acquired results clearly show that the evolution of 29Si and " Al spectra of the various samples may differ... 展开 The kaolinite-mullite reaction series of eight kaolin samples have been studied with XRD, IR, DTA and MAS NMR spectra. The acquired results clearly show that the evolution of 29Si and " Al spectra of the various samples may differ from each other significantly. In the metakaolinite studied, the Al is universally present and it appears as a sign of the variation of the structure and some properties of the metakaoliuites. It can be suggested from many experimental results that the high-temperatural phase occurring after the exothermal peak should be y -AI2O3 rather than Al-Si spinel, and the mullite-formation path in the studied samples involve two steps: first, the primary mullite farmed directly from the metakaolinite around 850 °C; Second step, the secondary mullite developped extensively by reaction between segregated SiO2 and y -AI2O3 at about 1200-1300 "C and the composition or/and structure of secondary mullite may be visibly different depending on the content of the impurity mica minerals. 收起