表面粗糙度对PS-PVD热障涂层陶瓷层沉积的影响

Effect of surface roughness on deposition of PS-PVD thermal barrier coating ceramic coating

研究基于等离子喷涂-物理气相沉积(PS-PVD)工艺的沉积表面的粗糙度对YSZ陶瓷层结构的影响,初步阐明了表面粗糙度对陶瓷层气相沉积过程的影响和涂层结构的形成规律。采用PS-PVD工艺在预制有NiCoCrAlYTa黏结层的K417G高温合金上制备YSZ陶瓷层;采用SEM、粗糙度检测仪、3D表面形貌仪等方法分析PS-PVD YSZ陶瓷涂层的形貌和结构特征。基体表面粗糙度对PS-PVD涂层结构有很大影响。结果表明:当基体表面粗糙度分别为 R a≤2μm, 2μm< R a<6μm, R a≥6μm时,涂层粗糙度分别在3.5~5,6~10,10~15μm区间;特征表面形貌"菜花头"的直径随着基体表面粗糙度的增加而逐渐增大, d P=38.5μm, d 280S =25.5μm, d 60S =38.7μm, d 24S =102μm, d S=137μm。表面粗糙度主要通过PS-PVD气相沉积过程中的阴影效应来影响涂层生长和形成差异性结构,随着基体表面粗糙度的增加,YSZ陶瓷层受阴影效应影响增大,表面形貌"菜花头"尺寸和柱状结构间间隙增大,形成更加疏松的结构。

The effect of surface roughness based on PS-PVD process on the structure of YSZ ceramic coating was studied. The influence mechanism of surface roughness on gas-phase deposition and structure formation of ceramic coating was discussed. YSZ ceramic coating was prepared by PS-PVD process on K417G superalloy prefabricated with NiCoCrAlYTa bond coating. The morphology and structural characteristics of PS-PVD YSZ coating were analyzed by means of SEM, roughness detector and 3D surface topography instrument. Substrate surface roughness has a great influence on PS-PVD coating structure. When the surface roughness of the substrate is R a≤2μm, 2μm< R a<6μm, and R a≥ 6μm, respectively, the coating roughness is in the range of 3.5-5, 6-10μm and 10-15μm, respectively. The diameter of cauliflower head increases with the increase of the surface roughness of substrate. The d P=38.5μm, d 280S =25.5μm, d 60S =38.7μm, d 24S =102μm and d S=137μm. In the process of PS-PVD gas-phase deposition, surface roughness mainly affects the growth and formation of coating differential structures through shadow effect. With the increase of substrate surface roughness, YSZ ceramic coating is affected by shadow effect and the size of cauliflower head and the gap width between columnar structures are increased, forming a relatively loose structure.