High SiMo cast iron components in automotive exhaust systems are exposed to high-temperature oxidation over time. Quantitative analysis of formed oxide scale is therefore important for the assessment of a component durability. The brittle nature of multilayered scale and thermal stress limits capture of a true topology using traditional 2D destructive cut and polish methods. In this study, nondestructive high spatial-resolution 3D µCT analysis was performed on 2.90-mm-diameter oxidized specimens which permitted direct observation with 3.5 µm pixel resolution. The specimens were oxidized in three sequential time steps for a total 100 h at 700 °C and 800 °C in air and combustion gas atmospheres. A MATLAB-coded algorithm was used to quantify the topology, thickness variation in internal and external scale layers, and scale/metal interface unevenness. Scale topology was linked to oxidation temperature and gas atmosphere. A water vapor environment increases scale/metal interface unevenness and scale layer thickness irregularity which were related to an accelerated oxidation rate.

中文翻译：

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高硅钼铸铁氧化过程中形成的鳞片拓扑的定量 μ-CT 分析

随着时间的推移，汽车排气系统中的高 SiMo 铸铁部件会受到高温氧化。因此，对形成的氧化皮进行定量分析对于评估部件的耐久性很重要。多层尺度和热应力的脆性限制了使用传统 2D 破坏性切割和抛光方法捕获真实拓扑。在这项研究中，对直径为 2.90 毫米的氧化样品进行了无损高空间分辨率 3D µCT 分析，允许以 3.5 µm 像素分辨率进行直接观察。样品在空气和燃烧气体气氛中在 700°C 和 800°C 下以三个连续的时间步骤氧化总共 100 小时。MATLAB 编码算法用于量化拓扑结构、内部和外部鳞片层的厚度变化以及鳞片/金属界面的不平整度。尺度拓扑与氧化温度和气体气氛有关。水蒸气环境增加了与加速氧化速率有关的氧化皮/金属界面不均匀性和氧化皮层厚度不规则性。