外加压应力对纯Ni在800 ℃空气中氧化行为的影响

来源期刊:中国有色金属学报2009年第12期

论文作者:周长海 马海涛 王 来

文章页码:2162 - 2166

关键词:Ni;压应力;扩散;高温氧化;空位

Key words:Ni; compressive stress; diffusion; high temperature oxidation; vacancy

摘    要:采用热重(TGA)方法测定纯Ni在800 ℃无应力及外加压应力为10和20 MPa时的氧化动力学曲线,通过扫描电镜观察有无压应力作用下的氧化膜表面和截面形貌,分析压应力作用下氧化动力学的变化和氧化膜的失效形式,从金属空位扩散的角度讨论压应力对纯Ni高温氧化行为的影响。结果表明:纯Ni在800 ℃时氧化,外加压应力增大其氧化速率,这是由于外加压应力对氧化膜结构的影响造成的;无压应力作用时,氧化膜为脊状氧化物;而在压应力作用下,氧化膜由粒状NiO组成,这增大晶界扩散的短路扩散;且压应力促进空位在氧化膜/金属界面的聚集、粗化,弱化界面,改变氧化膜的失效形式。

Abstract: The effect of compressive stress on the oxidation behavior of pure nickel was investigated by thermogravimetric analysis (TGA). Compressive samples were subjected to stresses of 10 and 20 MPa and the oxidation behavior was studied at 800 ℃ in air. The surface and cross section morphologies of the oxidized coating were analyzed by SEM. The change of oxidation kinetic and the failure form of the coatings under compressive stress were analyzed. The effect of compressive stress on the oxidation behavior of pure nickel at high temperature was discussed. The results show that the compressive stress increases the oxidation rate, which is attributed to the effect of compressive stress on the oxidized coating microstructure. Compared with the formation of ridge-like oxide, the compressive stress deduces the formation of particles oxide of NiO, which increases the short-circuit paths for diffusion. In addition, the compressive stresses induce vacancies coalescence at oxide-metal interface and cavities development, thus the strength of oxide-metal interface is weakened, and the failure form of the oxidized coating is changed.

基金信息:国家自然科学基金资助项目

有色金属在线官网  |   会议  |   在线投稿  |   购买纸书  |   科技图书馆

中南大学出版社 主办 版权声明   电话:0731-88830515 88830516   传真:0731-88710482   Email:administrator@cnnmol.com

互联网出版许可证:(署)网出证(湘)字第028号   湘ICP备09001153号