The high‐temperature oxidation of additively manufactured and chemically vapor infiltrated (3D‐printed SiC) has been compared to chemical vapor deposited (CVD) SiC. 100‐h isothermal exposures were conducted at 1425° and 1300°C at 1 atm under both dry air and steam environments. A SiC reaction tube was utilized to reduce silica volatility. After steam oxidation at 1425° and 1300°C, on the 3D‐printed SiC surface, which was intrinsically rougher than the CVD surface, scales were 70%–90% thicker at the convex regions compared to concave/flat regions. In the convex regions, large cracks perpendicular to the oxidizing interface were observed. After dry air oxidation, scale thicknesses were comparable between 3D‐printed SiC and CVD SiC, regardless of geometry. Finite element modeling, conducted to elucidate the relationship between SiC geometry and ß‐ to α‐cristobalite transformation stress, determined cristobalite transformation tensile stresses to be on the order of 10³ MPa during cool down, assuming a 6 vol% reduction. Compared to flat SiC substrates, tensile transformation stresses were elevated at concave regions and relaxed at convex regions. Combined with specimen mass gain (accounting for the rougher surface) of 3D‐printed SiC being 15%–32% higher for 3D‐printed SiC after 1300°C and 1425°C steam oxidation, the work presented concludes that the increased oxidation of 3D‐printed SiC is primarily caused by tensile hoop stresses driven by oxidation volume expansion. Lastly, the efficacy of the 3D‐printing method is demonstrated through the production of tristructural isotropic imbedded 3D‐printed SiC fuel forms.

中文翻译：

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在空气和蒸汽环境中3D打印SiC的氧化

添加剂制造和化学气相渗透（3D打印的SiC）的高温氧化已与化学气相沉积（CVD）SiC进行了比较。在干燥空气和蒸汽环境下，于1425°C和1300°C在1个大气压下进行100-h等温暴露。SiC反应管用于减少二氧化硅的挥发性。在1425°和1300°C下进行蒸汽氧化后，在3D打印的SiC表面上本质上比CVD表面更粗糙，与凹/平区域相比，凸区域的氧化皮厚70％–90％。在凸起区域，观察到垂直于氧化界面的大裂纹。经过干燥空气氧化后，无论几何形状如何，3D打印SiC和CVD SiC的氧化皮厚度都相当。有限元建模 在冷却过程中为³ MPa，假设减少了6 vol％。与平坦的SiC衬底相比，拉伸变形应力在凹形区域升高，而在凸形区域松弛。结合1300°C和1425°C蒸汽氧化后3D打印SiC的样品质量增益（占粗糙表面），其3D打印SiC的质量增加了15％–32％，得出的结论是3D氧化的增加预印碳化硅主要是由氧化体积膨胀驱动的张紧环应力引起的。最后，通过生产三向同性的3D打印SiC燃料模样，证明了3D打印方法的有效性。