Epitaxial growth and oxidation behavior of an overlay coating on a Ni-base single-crystal superalloy by laser cladding
Epitaxial growth and oxidation behavior of an overlay coating on a Ni-base single-crystal superalloy by laser cladding
复制标题
激光熔覆镍基单晶高温合金堆焊层的外延生长和氧化行为
DOI：
10.1016/j.jmst.2018.10.011
复制
发表时间：
2019
影响因子：
10.9
通讯作者：
Sun Xiaofeng
中科院分区：
文献类型：
--
作者：
Liang Jingjing;Liu Yongsheng;Li Jinguo;Zhou Yizhou;Sun Xiaofeng
采用激光熔覆的方法在单晶高温合金SRR99表面沉积了覆盖层材料。通过扫描电子显微镜（SEM）和x射线衍射仪（XRD）研究了涂层的微观结构和氧化行为。结果表明：虽然激光熔覆层的成分选择是基于ren<s:1> N5高温合金中的γ′成分，但熔覆层的初凝固相是γ- ni；此外，在激光熔覆条件下，从衬底外延生长出细小的平行枝晶，表明再现了衬底的单晶结构。当单晶MCrAlY涂层在1000℃氧化时，初始氧化过程中同时生成θ- al2o3和α- al2o3。随着氧化时间的延长，θ- al2o3的存在有利于氧化nial2o4尖晶石的形成。一旦尖晶石被观察到，它就会茁壮成长，并在鳞片中引起一些孔隙。当水垢厚度增加到6 ~ 7 μm时，水垢开始大面积剥落。
An overlay coating material was deposited on a single crystal superalloy SRR99 by laser cladding. The microstructure and oxidation behavior of this coating was investigated through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that although the composition of the coating was chosen based on the γ' composition in René N5 superalloy, the primary solidification phase of this coating during laser cladding was γ-Ni. Furthermore, under the laser cladding condition, fine parallel dendrites grew epitaxially in the coating from the substrate, indicating the single crystal structure of the substrate was reproduced. When the single crystal MCrAlY coating was oxidized at 1000℃, both θ-Al2O3and α-Al2O3formed during initial oxidation process. As the oxidation time proceeded, the presence of θ-Al2O3facilitated the formation of NiAl2O4spinel oxide. Once the spinel was observed, it flourished and induced some porosity in the scale. When the scale thickness increased to 6–7 μm, large area spallation of the scale began.