Journal of Materials Engineering and Performance ( IF 2.3 ) Pub Date : 2022-01-27 , DOI: 10.1007/s11665-021-06524-3 Sheng Liu 1 , Luming Xu 1 , Xiaokang Huang 1 , Jibing Xie 1 , Ze Chai 1 , Xiaoqi Chen 1, 2
High current density electrochemical machining (ECM) and high temperature corrosion behavior of nickel-based alloys have been well researched, but these works cannot provide reference for precision removal and refurbishment of Haynes 214 honeycomb structure carried out at ambient temperature. Thus, we propose micron-scale removal of the Haynes 214 structure by using the low current density ECM technique at ambient temperature and have systematically investigated the electrochemical dissolution behavior of Haynes 214 alloy under such process conditions. Compared with the NaCl solution, the NaNO3 solution is a preferred electrolyte for electrochemical machining of Haynes 214 due to its good electro-dissolution stability. For Haynes 214 machined in NaNO3 solutions, a low dissolution resistance can be obtained at the concentration of 7 wt.% and temperature of 40 °C, and in a current density range of 0.1~0.5 A·cm−2, a material removal rate at the micron scale (1.5~7.5 μm·min−1) is maintained. The breakdown of passive films on the Haynes 214 surface occurs preferentially at grain boundaries. Continuous Al enrichment is found throughout the polarization process. In the transpassive region, a large number of γ' particles are exposed on the Haynes 214 surface due to the preferential dissolution of γ matrix. The corrosion products identified by x-ray photoelectron spectroscopy are composed of Ni(OH)2, Cr2O3, Cr(OH)3, Al2O3, Fe2O3, and Fe3O4. This study provides an experimental and theoretical basis for the electrochemical machining of Haynes 214 alloy. The results demonstrate the viability of the proposed method for micron-scale removal of Haynes 214 honeycomb structure at ambient temperature.
中文翻译:
低电流密度电化学加工中Haynes 214蜂窝结构在NaNO3溶液中的电化学溶解行为
高电流密度电化学加工(ECM)和镍基合金的高温腐蚀行为已经得到很好的研究,但这些工作不能为在环境温度下进行的Haynes 214蜂窝结构的精密去除和翻新提供参考。因此,我们提出了在环境温度下使用低电流密度 ECM 技术对 Haynes 214 结构进行微米级去除,并系统地研究了 Haynes 214 合金在这种工艺条件下的电化学溶解行为。与NaCl溶液相比,NaNO 3溶液因其良好的电溶解稳定性而成为Haynes 214电化学加工的优选电解质。用于以 NaNO 3加工的 Haynes 214在 7 wt.% 的浓度和 40 ℃的温度下,在 0.1~0.5 A·cm -2的电流密度范围内,材料去除率达到微米级(1.5 ~7.5 μm·min -1 ) 保持不变。Haynes 214 表面钝化膜的破坏优先发生在晶界处。在整个极化过程中发现了连续的铝富集。在穿透区,由于γ基体的优先溶解,大量γ'粒子暴露在Haynes 214表面。X射线光电子能谱鉴定的腐蚀产物由Ni(OH) 2、Cr 2 O 3、Cr(OH) 3、Al 2组成O 3、Fe 2 O 3和Fe 3 O 4。该研究为Haynes 214合金的电化学加工提供了实验和理论依据。结果证明了所提出的在环境温度下以微米级去除 Haynes 214 蜂窝结构的方法的可行性。