Theoretical Investigation of the Interfacial Reactions during Hot-Dip Galvanizing of Steel
Theoretical Investigation of the Interfacial Reactions during Hot-Dip Galvanizing of Steel
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DOI：
10.1007/s11661-008-9748-2
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发表时间：
2009-01
期刊：
影响因子：
--
通讯作者：
G. Mandal;R. Balasubramaniam;S. Mehrotra
中科院分区：
文献类型：
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作者：
G. Mandal;R. Balasubramaniam;S. Mehrotra
在现代镀锌生产线上，钢带一进入含铝锌浴，钢带和液锌合金界面处就会发生两种反应：(1)铁从钢带表面迅速溶解，提高了钢带液界面处液相中的铁浓度；(2)铝对铁的亲和力较大，在带-涂层界面形成稳定的铝-铁金属间化合物层。本研究的主要目的是建立一个简单而现实的数学模型，以便更好地理解带钢和液锌合金界面的镀锌反应动力学。在本研究中，提出了一个模型来模拟不同工艺参数对铁在镀液中溶解的影响，以及在衬底-涂层界面上富铝抑制层的形成。基于导热传热和对流传热机理，对浸没带钢的瞬态温度分布进行了预测。假设浸入式带材的冷却路径由一系列无限小时间步长等温保持组成，从而预测了衬底-涂层界面处的抑制层厚度。通过考虑各保温时间下的成核和生长机制来评估镀锌反应的影响，并以此来估计浸泡时间对缓蚀层形成机制的总影响。铁的溶解模型是根据公认的扩散原理建立的，考虑了在缓蚀层形成过程中金属间化合物覆盖在带材表面的面积分数。通过对工艺参数的优化，可以有效地利用该模型对槽内的渣滓生成进行监测。将理论预测与其他研究人员的发现进行比较。模拟结果与其他研究人员的理论和实验观察结果吻合较好。
In the modern galvanizing line, as soon as the steel strip enters the aluminum-containing zinc bath, two reactions occur at the strip and the liquid-zinc alloy interface: (1) iron rapidly dissolves from the strip surface, raising the iron concentration in the liquid phase at the strip-liquid interface; and (2) aluminum forms a stable aluminum-iron intermetallic compound layer at the strip-coating interface due to its greater affinity toward iron. The main objective of this study is to develop a simple and realistic mathematical model for better understanding of the kinetics of galvanizing reactions at the strip and the liquid-zinc alloy interface. In the present study, a model is proposed to simulate the effect of various process parameters on iron dissolution in the bath, as well as, aluminum-rich inhibition layer formation at the substrate-coating interface. The transient-temperature profile of the immersed strip is predicted based on conductive and convective heat-transfer mechanisms. The inhibition-layer thickness at the substrate-coating interface is predicted by assuming the cooling path of the immersed strip consists of a series of isothermal holds of infinitesimal time-step. The influence of galvanizing reaction is assessed by considering nucleation and growth mechanisms at each hold time, which is used to estimate the total effect of the immersion time on the formation mechanism of the inhibition layer. The iron- dissolution model is developed based on well established principles of diffusion taking into consideration the area fraction covered by the intermetallic on the strip surface during formation of the inhibition layer. The model can be effectively used to monitor the dross formation in the bath by optimizing the process parameters. Theoretical predictions are compared with the findings of other researchers. Simulated results are in good agreement with the theoretical and experimental observation carried out by other investigators.