A KINETIC-STUDY ON OXIDATION OF NIOBIUM CARBIDE

被引:29
作者
SHIMADA, S
INAGAKI, M
机构
[1] Department of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo
关键词
D O I
10.1016/0167-2738(93)90122-J
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The isothermal oxidation of NbC powders was carried out at temperatures of 420-600-degrees-C and oxygen pressures of 4, 8 and 16 kPa, using an electro-microbalance. The oxidation process was divided into three steps I to III. In step I, oxidation occurs linearly in initial period (a degree of oxidation (alpha) < 10-20%). In step II (10% < alpha < 30%), oxidation proceeds by a diffusion-controlled process below 490-degrees-C, whereas oxidation was extremely accelerated by large heat evolution due to the crystallization of Nb2O5 formed above that temperature. A phase boundary-controlled process operates in step III (alpha > 30%).
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页码:312 / 317
页数:6
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