Abstract:A porous Si3N4 were tested at the static and micro-dynamic condition of the oxidizing atmosphere by
TG-DSC,XRD,SEM,ICP at four different temperatur with the highest temperature of 1 400℃. The testing results
showed that oxidation reaction was very weak before 800℃ at 1atm and in static condition. Oxidation reaction become
obvious after 800℃ and weight increase rapidly after 1 000℃. Preferential oxidation occurs at the surface and the hole
wall of the sample,then occurs at the hole gap in internal. The oxidation reaction endothermic is controlled by chemical
kinetics to the interface,and SiO2 is main oxidation product. When the SiO2 covers the surface of the Si3N4 completely,
and Si2N2O will appear with the temperature increasing and holding time prolonging. It is necessary to pay attention
to prevent brittle fracture of the sample at high temperature. In addition, the dynamic oxidation atmosphere
will accelerate the oxidation of Si3N4 in same temperature, especially to the porous and powder samples.
