Incoloy 800H於1000℃空氣中循環氧化行為之探討

A Study of Cyclic Oxidation Behavior of Incoloy 800H at 1000 ℃ in Air

本研究探討兩種不同廠家的Incoloy 800H在1000℃空氣中循環氧化（每週期氧化50分鐘，冷卻10分鐘）行為。研究方法包括合金光學顯微鏡（OM）觀察、試片表面溫度熱履歷量測、氧化試驗、氧化量量測，進一步以掃描式電子顯微鏡／能量散佈光譜儀（SEM/EDS）及X光繞射儀（XRD）解析氧化皮膜層。結果顯示在氧化初期，皮膜／底材界面有含Si氧化物結瘤滲入底材，形成鍵結，銹皮不易剝落，氧化失重很少，超過一定時期結瘤消失，故氧化失重快速增加。本研究中，底材高鋁且低矽的合金耐循環氧化性能略優於低鋁且高矽的合金，應與前者可生成滲入底材之含Al氧化物有關。Cr2O3富集在內層皮膜可使該氧化層不易剝落，但無法防止外層皮膜剝落。

Cyclic oxidation (50 min oxidation + 10 min cooling) behaviors in air at 1000 ℃ of two Incoloy 800H alloys from different mills have been investigated. The experimental methods included optical microscopy (OM) observation, measurement of surface thermal history, oxidation test, and measurement of weight change during test. Furthermore, oxide scales were analyzed using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X ray diffraction (XRD). The results showed that, in the early stage of oxidation, a number of nodules composed of Si-containing oxides formed and intruded from the oxide scale/substrate interface into the alloy. These nodules acted as a bonding between the scale and the substrate and protected the scale from spalling. After a certain period the nodules disappeared and the weight loss significantly increased. In this investigation, the alloy with high [Al] and low [Si] possessed better cyclic oxidation resistance than that with low [Al] and high [Si], probably due to the Al-containing oxide scale intruded into the alloy grain boundary. The Cr2O3 in the inner scale also contributed to the adherence of the inner scale itself, but could not prevent the outer scale from spalling.