Research On Sinterability And Mullitization Mechanisms Of Andalusite From Mei County Shannxi

Andalusite is a kind of high-qulity natural refractory raw materials, and andalusite-based refractory has good high temperature mechanical properties and thermal shock resistance, which make it find a wide use in iron and steel industry and other high temperature industries. Mei County Shannxi rich in andalusite resource, which has not been developed extensively,so sinterability and mullitization mechanisms of the andalusite were mainly researched in my paper to provide probably theoretical reference on its use.Above all , two kinds of different specimens were prepared , one was formulated toally in andalusite of Mei County Shannxi,and the other was composed of andalusite and commercial alumina, then the specimens were sintered at 1350℃, 1450℃ and 1550℃ respectively ,so the effects of sintering temperature and addition of commercial alumina on sinterability of andalusite-based materials were investigated with physical properties measurement;And then, the muUitization mechanisms and the microstructural transformation in sintering of Mei County andalusite were discussed primarily by means of XRD and SEM and EDS, the following results could be drawn:Under condition of experimental temperature, specimen S1 behaves better sinterability and characteristic of expansion, but specimen S2 is sintered insufficiently and exhibits characteristic of shrinkage;The compression strength of specimens at room temperature increases with rise of sintering temperature, and their relation almostly is linear, and the compression strength of specimen S1 is larger than specimen S2 at same sintering temperature.Volume fraction of mullite originated from specimens severely increases with rise of sintering temperature before 1450℃, somewhat changes after 1450℃;Before 1450℃ muUitization of andalusite elementally finishes, and then occurrence of mulliteprimarily depends on sencondary mullitization, and quartz originated from mullitization appears in form of non-crystal largely at room temperature;Degree of mullitization before 1450 °C is highly sensitive to sintering temperature, and then non-sensitive after 1450 °C.Mullitization of andalusite probably occures at boundary of andalusite grains at first, and then expands into centre of grain, and mullite appears in form of lathlike grains;In the course of sintering, solid sintering plays an important role at 1350 °C, and liquid sintering is dominant at 1450 °C, and recrystallization and aggregating recrystallization result in grain growth at 1550°C;with rise of sintering temperature, grains of mullite grow up perfectly, and becomes coarse, even net;Under condition of same experiment, grains of specimen SI is somewhat coarser than that in specimen S2.