Fe-B合金耐锌液冲刷腐蚀的交互作用及其转型机制研究

The abominable liquid zinc erosion-corrosion of the equipment and core components is deemed to be an important corrosion damage process in continuous hot-dip galvanizing line. However, the interaction and strong synergistic effect between erosion and corrosion in liquid zinc of materials are the main damage mechanism which can induce and accelerate the damage process of components and parts used in continuous hot-dip galvanizing line. It is of practical importance and scientific significance for design and improvement of a material immersed in liquid zinc to investigate the interaction of erosion-corrosion and its transition mechanism. Based on the corrosion interface pinning effect and Al-inhibition behavior of microstructure-controlled tow-phase Fe-B alloy corroded in liquid zinc, the aim of the work in this project is to investigate the interaction and its transition mechanism of liquid zinc erosion-corrosion for Fe-B alloy. The rotation-disk experimental technique in this work is adopted, and the erosion and corrosion process are separated respectively from the system. Thus, the interaction and synergistic effect between erosion and corrosion in liquid zinc of Fe-B alloy are studied, and a new quantitative estimating model of the interaction created by liquid zinc erosion and corrosion is naturally established. Additionally, the interaction maps of erosion-corrosion and evolution patterns are experimentally determined, which can reveal the liquid zinc erosion-corrosion mechanism in deep. According to the experimental results and analysis mentioned above, the improved microstructures of Fe-B alloy are obtained by directional solidification, and the grains of oriented Fe2B and matrix phase are well refined. In this case, the well refined Fe-B alloy fabricated by directional solidification is selected to evaluate the influence on the interaction of erosion-corrosion in liquid zinc, especially for the synergistic effect between Fe2B phase and matrix structure of Fe-B alloy corroded in liquid zinc. It is revealed that the examination and evaluation of the interaction between erosion and corrosion in liquid zinc and its damage mechanism are very important significance, and it can also provide a design method and improvement for effective control of erosion-corrosion interaction and the enhanced liquid zinc erosion-corrosion resistance of Fe-B alloy as a component material utilized in continuous hot-dip galvanizing line.

锌液冲刷腐蚀已成为热镀锌生产线上核心部件的重要损伤过程，而冲刷与腐蚀间的交互作用是诱发并加速该过程的主要机制。研究锌液冲刷腐蚀的交互作用及其转型机制对设计并实现材料高耐锌蚀性能具有重要的科学意义和实用价值。本项目基于双相Fe-B合金微尺度调控下锌蚀界面独有的"钉扎效应"和含铝添加剂下腐蚀抑制行为的基础上，以冲刷腐蚀交互作用及转型机制为研究目标，采用旋转盘技术将冲刷与腐蚀分量从系统中显化并表征，进而明确冲刷与腐蚀间的交互作用及影响效应，构建冲刷腐蚀交互作用新的定量模型；并通过强化冲刷与腐蚀来构筑交互作用的转型机制图，揭示冲刷腐蚀间的演变规律，阐明锌液冲刷腐蚀的控制机制。基于上述结果，利用定向凝固技术来调控材料的微尺度，探索微尺度协同效应对冲刷腐蚀交互作用的影响。研究结果对揭示锌液冲刷腐蚀交互作用的损伤机制具有重要的理论意义，并为有效控制交互作用量、强化材料冲蚀抗力提供新的设计方法与控制途径。

热镀锌设备的关键零部件长期服役在450~600℃的高温锌液中，承受锌液强烈的冲刷-腐蚀，成为零部件的重要损伤过程，其交互作用是诱发并加速损伤过程的主要机制。本项目以流动锌液冲刷-腐蚀交互作用为研究目标，采用旋转盘技术研究了强腐蚀（提高锌液温度）和强冲刷（提高冲刷速度）过程，揭示冲刷-腐蚀的演变规律。同时，利用定向凝固技术来调控/Fe2B组相形态，探索Fe2B形态、位向、尺度等对冲刷-腐蚀交互作用的影响机制。主要获得以下结论：.Fe-B合金在锌液冲刷-腐蚀过程中，锌液冲刷加速了铁锌腐蚀产物移除，加快了铁锌原子的互扩散过程进而诱发腐蚀反应，使得冲刷强烈加剧腐蚀；腐蚀导致的疏松铁锌腐蚀产物层，使网状Fe2B失去基体支撑而裸露于冲刷-腐蚀界面，强烈促进冲刷对腐蚀产物的移除、残留Fe2B的损伤过程，二者相互促进产生强烈交互作用。冲刷-腐蚀初期，基体的快速溶解、剧烈铁锌腐蚀反应使得冲刷与腐蚀之间产生强烈的交互作用；随时间延长，界面前沿冲刷-腐蚀层增厚，对传质过程产生阻挡，弱化了冲刷与腐蚀的交互作用。.锌液温度460℃、冲刷速度60rpm，当冲刷-腐蚀进入稳定状态后，与普通试样冲刷-腐蚀交互作用相比，平行试样降低12.76%，垂直试样下降高达49.84%。其主要原因为，Fe2B择优取向垂直冲刷-腐蚀界面时，取向Fe2B诱导腐蚀产物ζ-FeZn13向外侧取向生长；二者产生强烈的 界面“钉扎效应”，形成稳定抗冲刷屏蔽层，弱化了交互作用。.锌液温度升高导致平行试样中Fe2B逐层剥落；当温度达550℃时，与平行试样冲刷-腐蚀交互作用速率相比，普通试样降低52.95%；垂直试样则下降75.52%。冲刷速度的提高加速Fe2B破碎、剥落，冲刷与腐蚀之间产生强烈的交互作用。冲刷角度增加弱化了切向剪切作用、增强法向冲击作用，使普通试样冲刷-腐蚀交互作用最弱。