The steam oxidation behavior of Zr-based Zircaloy-4 fuel cladding was studied at 1273 K with two different surface roughness levels. Steam was introduced either at room temperature (RT) or at 1273 K. Weight gain kinetics were evaluated by post-test weight measurement, and the reaction products and alloy microstructure were evaluated using optical microscopy. Hydrogen pick-up was measured by the gas extraction technique. Specimen surface roughness did not affect the oxidation kinetics or the hydrogen absorption. The time to breakaway oxidation was suppressed when steam was introduced at RT, and the oxide was more adherent, suggesting superior mechanical properties. When steam was introduced at 1273 K, an undulated oxide–metal interface formed earlier and a higher amount of hydrogen was absorbed by cladding before the kinetic transition. The alloy grain grew into larger size in the condition when steam was injected at 1273 K compared to the condition when steam was injected at RT, which may affect the observed behavior. After the oxide breakaway, the rate of hydrogen absorption accelerated substantially independent of the temperature of steam injection.

中文翻译：

---

试样表面粗糙度和蒸汽喷射温度对Zry-4燃料包壳在1273 K蒸汽中分离氧化行为的影响

研究了 Zr 基 Zircaloy-4 燃料包壳在 1273 K 和两种不同表面粗糙度水平下的蒸汽氧化行为。在室温 (RT) 或 1273 K 下引入蒸汽。通过测试后的重量测量评估增重动力学，并使用光学显微镜评估反应产物和合金微观结构。氢气吸收量通过气体提取技术测量。试样表面粗糙度不影响氧化动力学或氢吸收。当在室温下引入蒸汽时，氧化分离的时间受到抑制，并且氧化物的粘附性更强，表明具有优异的机械性能。当在 1273 K 下引入蒸汽时，较早形成起伏的氧化物 - 金属界面，并且在动力学转变之前包层吸收了更多的氢。与在 RT 下注入蒸汽的条件相比，在 1273 K 下注入蒸汽的条件下合金晶粒长大成更大的尺寸，这可能会影响观察到的行为。氧化物分离后，吸氢速度明显加快，与蒸汽注入温度无关。