Morphological evolution of porous silicon nitride ceramics at initial stage when exposed to water vapor

JOURNAL OF ALLOYS AND COMPOUNDS

卷:725

Article

Wang, Enhui^1,2  Li, Bin³  Yuan, Zhangfu³  Chen, Junhong⁴  Chou, Kuo-Chih¹  Hou, Xinmei^1,2 

[1] Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China

[2] Wuhan Univ Sci & Technol, State Key Lab Refractories & Met, Wuhan, Hubei, Peoples R China

[3] Univ Sci & Technol Beijing, Collaborat Innovat Ctr Steel Technol, Beijing 100083, Peoples R China

[4] Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China

关键词: Porous Si3N4 ceramics;    Morphology;    Kinetics;    Water vapor;   

DOI  :  10.1016/j.jallcom.2017.07.249

来源: Elsevier

【 摘 要 】

The reaction behavior of porous silicon nitride (Si3N4) ceramics at initial stage when exposed to water vapor ranging from 5 to 20 vol% at 1200 degrees C was investigated using online thermogravimetric (TG) method. The effect of water vapor on the surface morphology and corrosion interface of porous Si3N4 ceramics was characterized using scanning electron microscopy (SEM). The results show that water vapor can aggravate the reaction and the reaction rate accelerates with the water vapor content increasing. As for the morphological evolution, water vapor promotes the formation of interconnected pores, which is possibly caused by the breakage of amorphous SiO2 by inner massive gas product and gas releasing through crystalline SiO2. Based on these, a gas-solid model is adopted to describe the effect of different water vapor partial pressure on the reaction kinetics and obtains a good agreement. (C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

Free