热浸镀锌铝的界面反应机理

彭浩平^{1, 2, 3}，苏旭平¹，王建华¹，李 智³，刘 亚¹

(1. 常州大学 先进金属材料常州市重点实验室，常州 213164；
2. 常州大学 江苏省油气储运技术重点实验室，常州 213016；
3. 湘潭大学 材料设计及制备技术湖南省重点实验室，湘潭 411105)

摘 要：通过热浸镀和扩散偶试验研究铁基与4种锌铝熔池成分合金Zn-0.2%Al、Zn-5%Al、Zn-25%Al、Zn-55%Al(质量分数)之间的界面反应过程，提出热浸镀锌铝中扩散通道移动对合金层形成的控制机理。结果表明：热浸镀(扩散偶)初期，扩散通道均沿两相区共轭线(tie-line)穿过熔池成分液相与对应的Fe-Al化合物构成的两相区，铁基表面优先形成对应的Fe-Al化合物的连续层状组织。随着热浸镀(扩散)时间的延长，扩散通道具有逐渐向两扩散组元成分点连线移动的趋势，一旦扩散通道切割熔池成分液相与对应的Fe-Al化合物构成的两相区共轭线，初期形成的Fe-Al化合物层失稳破裂，导致镀层合金层(扩散层)快速增厚。

关键词：热浸镀锌铝；扩散偶；Zn-Fe-Al体系；界面反应；扩散通道

Interface reaction mechanism for galvanizing in Zn-Al baths

PENG Hao-ping^{1, 2, 3}, SU Xu-ping¹, WANG Jian-hua¹, LI Zhi³, LIU Ya¹

(1. Key Laboratory of Advanced Metal Materials of Changzhou City, Changzhou University, Changzhou 213164, China;
2. Key Laboratory of Oil and Gas Storage and Transportation Technology of Jiang)

Abstract:By galvanizing and diffusion couple experiments, the interface reactions between the iron-base and different baths, which are Zn-0.2%Al, Zn-5%Al, Zn-25%Al and Zn-55%Al (mass fraction), were studied, respectively. The controlled mechanism of alloy layer formation in the process of galvanizing by the diffusion path change was proposed. The results show that in the beginning of galvanizing (diffusion couple), the diffusion path crosses the two-phase region of melting bath point composition and the relevant Fe-Al compound following its tie-line, the Fe-Al compound forms on the iron-based surface firstly. With the immersion (diffusion) time increasing, the diffusion path trends to move gradually to the line connecting with two diffusion component points. Once the diffusion path cuts the tie-line of the two-phase region of melting bath and the relevant Fe-Al compound, the first Fe-Al compound layer is steadiness losing and breaking, which makes the thickness of coating alloy layer (diffusion layer) increase rapidly.

Key words:hot-dipping Zn-Al; diffusion couple; Zn-Fe-Al system; interface reaction; diffusion path