The addition of zirconium to aluminide coatings: The effect of the aluminide growth mode
The addition of zirconium to aluminide coatings: The effect of the aluminide growth mode
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在铝化物涂层中添加锆：铝化物生长模式的影响
DOI：
10.1016/j.surfcoat.2019.125066
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发表时间：
2019
影响因子：
5.4
通讯作者：
F. S. Nogorani
中科院分区：
文献类型：
--
作者：
M. S. Zare Mohazabie;F. S. Nogorani
氧化铝前体涂层（如镍铝化物）是对抗燃气涡轮机热段部件腐蚀性工作环境的基本方法。锆对铝化物涂层的循环氧化寿命的积极影响已被报道。本文报道了铝化物涂层的生长方式对锆改性铝化物涂层的微观结构的影响。在铝、氯化铵、氧化锆和氧化铝的粉末混合物中使用卤化物活化的包渗工艺在760和1040 °C下分别进行向内和向外生长的渗铝工艺。采用场发射扫描电镜（FESEM）、能谱仪（EDS）和X射线衍射仪（XRD）研究了涂层的微观结构。结果表明，外层涂层含有高含量的Zr，主要结合在NiAl基体中的第二相如AlNi2Zr中。相反，在向内生长的铝化物涂层中的Zr浓度不超过1原子百分比，并且观察到高活性铝化物涂层的典型显微结构。讨论了包埋渗过程中的化学反应和渗层形成机理。
Alumina-former coatings such as nickel aluminides have been the essential approach to combating the aggressive service environment of gas turbine hot section components. The positive effects of zirconium on the cyclic oxidation lifetime of aluminide coatings have been reported. The current paper has reported the effect of the growth mode of the aluminide coating on the microstructure of the Zr-modified aluminide coating. The aluminization process was carried out using the halide activated pack cementation process in the powder mixtures of aluminum, ammonium chloride, zirconium oxide, and alumina at 760 and 1040 °C for the inward and outward growth, respectively. The microstructures of the coatings were studied using FESEM, EDS and XRD. The results showed that the outward coatings contain a high level of Zr mainly incorporating it in the second phases such as AlNi2Zr in a matrix of NiAl. In contrast, the Zr concentration in the inwardly grown aluminide coatings did not exceed the 1 atomic percentage and the typical microstructure of the high activity aluminide coatings was observed. The chemical reactions involved in the pack cementation process and the mechanism of the coating formation were discussed.