An investigation on the effect of atmosphere, degree of compacting, heating rate, and presence of diluent on the mechanism of evolutions occurred in the Al+B2O3+Si+WO3 aluminothermic System

In this study, the effect of various parameters including degree of compacting, heating rate, atmosphere, and diluent additive was investigated on the thermal analysis curves and phases formed in the Al+B2O3+Si+WO3 aluminothermic system in order to production of a hybrid composite powder of Al2O3-WxBy-WxSiy. The results showed that the change of atmosphere from argon to air limits the formation of tungsten silicide ‎and boride phases and then increases the temperature of formation of these phases. However, the argon atmosphere facilitates the formation of the mullite phase. Higher degree of compaction can improve the kinetic of for aluminothermic combustion reactions and thereby not only can decrease the temperature range of formation tungsten silicide ‎and borid but also limits the volume fraction of mullite phase. Furthermore, an increase in the heating rate from 20 to 100 °C.min-1 shifts the peaks of formation of tungsten silicide ‎and boride to higher temperatures. Also, the presence of ZrO2 as a diluent agent decreases the temperature of combustion process.