多孔氮化硅高温氧化特性分析  

Analyzing The Oxidation Behavior of Porous Si_3N_4 at High Temperature

作　　者：何凤梅[1] 陈聪慧[1] 杨景兴[1] 黄娜[1] 王晓叶[1] 

机构地区：[1]航天材料及工艺研究所,先进功能复合材料技术重点实验室,北京100076

出　　处：《宇航材料工艺》2014年第1期101-106,共6页Aerospace Materials & Technology

摘　　要：采用TG-DSC、XRD、SEM、ICP等分析手段,对某一典型多孔氮化硅样品进行4个不同温度点的静态和微动态连续氧化试验,最高氧化温度为1 400℃。结果表明:多孔氮化硅在0.1 MPa静态空气气氛下,800℃之前,氧化反应非常微弱,800℃以上可见明显的氧化反应,1 000℃以上氧化反应加剧,增重速率加快,并优先发生在表面与外部孔壁处,之后再发生在样品的内部孔隙处,氧化反应受界面处的化学动力学控制,以被动氧化为主,主要生成物是SiO2,属吸热反应。当生成的SiO2将氮化硅表面和孔壁处覆盖时,在其界面处,随着温度的进一步升高或时间的延长,会生成Si2N2O,且需要注意防范样品可能出现脆性断裂情况。此外,同等温度下,动态氧化气氛将加速氮化硅的氧化,特别是多孔和粉末状样品。A porous SiaN4 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 l atm 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 chemi- cal kinetics to the interface,and SiO2 is main oxidation product. When the SiO2 covers the surface of the Si3N4 com- pletely, and Si2 N20 will appear with the temperature increasing and holding time prolonging. It is necessary to pay at- tention to prevent brittle fracture of the sample at high temperature. In addition, the dynamic oxidation atmosphere will accelerate the oxidation of Si3 N4 in same temperature, especially to the porous and powder samples.

关 键 词：氮化硅 多孔 氧化特性 高温 陶瓷材料 

分 类 号：TB335[一般工业技术—材料科学与工程] TB3