In the present study, microstructural analysis was carried out to investigate the effect of substrate surface chemistry on splat formation. Ni powder was sprayed onto stainless steel substrates exhibiting two different surface conditions (polished and oxidized) by high-velocity oxy-fuel (HVOF) thermal spray. X-ray photoelectron spectroscopy (XPS) was employed to investigate the chemical state of the surfaces which indicated the presence of the adsorbates on the oxidized substrate. Single splats of different morphologies from both samples were examined using a range of characterization techniques including scanning electron microscopy (SEM), focused ion beam (FIB) microscopy and transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDS) interfaced to both SEM and TEM. This provided information on the particle solidification behavior and splat formation mechanism following impact on substrates with distinct surface conditions. The results showed the effect of oxidized surface adsorbates on splat morphology, pore formation and splat–substrate interactions. These microstructural findings, aided by theoretical models, revealed that a mixture of mechanical and metallurgical bonds exists between the splats and both substrates.

中文翻译：

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超音速火焰喷涂镍在抛光和氧化不锈钢基材上的显微结构表征

在本研究中，进行了显微结构分析以研究基材表面化学对飞溅形成的影响。通过高速氧燃料 (HVOF) 热喷涂，将镍粉喷涂到具有两种不同表面条件（抛光和氧化）的不锈钢基材上。X 射线光电子能谱 (XPS) 被用来研究表面的化学状态，这表明被氧化的基材上存在吸附物。使用一系列表征技术检查来自两个样品的不同形态的单个碎片，包括扫描电子显微镜 (SEM)、聚焦离子束 (FIB) 显微镜和透射电子显微镜 (TEM) 以及能量色散 X 射线光谱 (EDS) 接口SEM 和 TEM。这提供了在对具有不同表面条件的基材产生影响后颗粒凝固行为和飞溅形成机制的信息。结果表明氧化表面吸附物对splat形态、孔形成和splat-底物相互作用的影响。在理论模型的帮助下，这些微观结构的发现表明，在板片和两种基材之间存在机械和冶金结合的混合物。