加氧处理对700℃级超超临界锅炉合金GH2984饱和蒸汽氧化行为的影响

Oxygenated treatment on Saturated Vapour Oxidation Behaviors of GH2984 Alloys for 700 °C Ultra-supercritical Boilers

摘要:

采用氧化增重法、X射线衍射、扫描电子显微镜研究了不同溶解氧浓度下700℃级超超临界锅炉用GH2984镍基合金的750℃饱和蒸汽氧化行为,结果表明： GH2984合金在不同溶解氧浓度(10ppb、5ppm)的水蒸气中生成的氧化层均为单层结构,主要由连续Cr2O3和少量弥散或局部聚集分布着Al2O3、TiO2内氧化产物组成。加氧处理会造成GH2984合金氧化膜厚度增加和内氧化现象明显,并使得表面零散分布的Fe2O3瘤状凸起消失,转而生成更多富Cr瘤状凸起。另外,水中溶解氧浓度上升未引起GH2984合金表面Cr2O3氧化膜的加速挥发,但降低了氧化膜中的TiO2含量。

Abstract:

The saturated vapor oxidation behaviors of GH2984 alloys at 750 °C were investigated by oxidation weight increasing method, X-ray diffraction and scanning electronic microscopy in different dissolved oxygen concentrations. The results showed that the oxide film of GH2984 alloys in different dissolved oxygen concentrations was of a single layer consisting of continuous Cr2O3 and disperse or local clustered internal oxidation products of Al2O3 and TiO2. The oxidation weight gain of GH2984 alloys slightly increased with increment of the dissolved oxygen concentrations in water vapor. Oxygenated treatment could accelerate the internal oxidation phenomenon, enhance the oxidation film thickness and make the scattered nodular bulges of Fe2O3 disappear and more Cr-rich nodular bulges form. Moreover, high dissolved oxygen concentrations did not affect the stabilization of Cr2O3 but decrease TiO2 content in the oxide film.