关于莫来石的正电子湮没研究

An Investigation on the Microscopical Structure of Mullite Brick by Positron Annihilation

<正>对于合成莫来石,大多数通过显微镜、扫描电镜进行定性分析,至今未找出一种较合理适用的方法来描述合成莫来石的显微结构。本文采用正电子湮没技术研究这一问题。1.实验方法与结果 本文工作用烧结法合成莫来石,工艺为配料、细磨混合、成型、烧结。按原料Al_2O_3/SiO_2的不同配比,制成HM3,HM4,A,B_2,HM5,B,HM6共7组不同的试样,样品为φ12×2（mm）的圆片。烧结温度分别为1600℃,1650℃,1700℃,均保温3h。莫来石的分子式为3Al_2O_3·2SiO_2。 莫来石的合成原料化学组成见表1.表1中只给出了6组,样品成分是通过化学分析的方法获得的,Al_2O_3/SiO_2指的是它们的重量比。

The microscopical structure of mullite brick is investigated by means of positron annihilation technique.It is found from the lifetime τ1 of positron annihilation that positronium has been formed in most of the samples. From the relation between the capture state lifetime τ2 of positron annihilation and the sintering temperasure T (1600℃, 1650℃, 1700℃) plotted, it can be seen that the samples of the same series do exhibit an identical varying tendency. At 1650℃, more precipitation of giass phase has been observed, which supports the theory of the microcrystalline structure. By increasing the ratio of A12O3 to SiO2, the content of the mullite can be increased and that of the glass phase decreased.