无压烧结Si_3N_4陶瓷在加湿空气中的氧化行为

QXIDATION OF SINTERED Si_3N_4 IN WET AIR

研究了无压烧结 Si3N4 陶瓷在 1 2 0 0℃、在流动的含水汽 2 0 vol%的加湿空气中的氧化行为。研究表明 ,Si3N4 陶瓷在加湿空气中氧化比在自然空气中氧化剧烈。动力学研究表明 ,Si3N4 陶瓷在加湿空气中氧化分两个阶段进行 ,第一阶段为直接氧化 ,此时 ,氧化增重与氧化时间成线性关系 ,第二阶段为钝化氧化 ,此时 ,氧化主要通过离子和分子的扩散来完成。

The oxidation of sintered Si 3N 4 was investigated in flowing wet air with 20vol% H 2O at 1200℃.The oxidation of sintered Si 3N 4 in wet air is more severe than that in natural air.Kinefic measurement indicates that the oxidatien of sintered Si 3N 4 in wet air shows two processes.During the first Process which is called direct oxidation,Si 3N 4 reacts with H 2O and O 2 directly,and the relation of weight gain-oxidation time is linear.The second process which is called passive oxidation is controlled mainly by diffusion of ions and molecules through the oxide layer.