Phase Transition Behavior Of Ammonium Molybdate Thermal Decomposition And Kinetic Study

Thermal decomposition of ammonium molybdate is an important link in the powder metallurgy process of molybdenum. In this paper, the phase transformation and reaction kinetics of thermal decomposition of ammonium molybdate were studied with SEM,XRD,TGA,DTA and so on. The results showed that the dynamic thermal decomposition law of different ammonium molybdenum raw materials is announced, in which it is presented that the thermal decomposition of ammonium dimolybdate has two steps but the ammonium tetramolybdate's has only one step. The rate equation of ammonium dimolybdate in the thermal decomposition reaction is setuped.The first step is (?) and the secondstep is (?). While the rate equation ofammonium tetramolybdate in the thermal decomposition reaction is(?).when the temperature is 500℃, ammonium dimolybdate completely transforms into MoO₃. But the temperature of ammonium tetramolybdate completely transforming into MoO₃ is 450℃. In order to obtain the fine particle MoO₃, the thermal decomposition temperature can't exceed 700℃.