High-temperature oxidation of CrAlYN coatings: Implications of the presence of Y and type of steel

SURFACE & COATINGS TECHNOLOGY

卷:354

Article

Rojas, T. C.¹  Dominguez-Meister, S.^1,2  Brizuela, M.²  Sanchez-Lopez, J. C.¹ 

[1] Univ Seville, Inst Ciencia Mat Sevilla, CSIC, Avda Amer Vespucio 49, Seville 41092, Spain

[2] TECNALIA, Mikeletegi Pasealekua 2, Donostia San Sebastian 20009, Spain

关键词: Rare earth elements;    Sputtered films;    Steel;    STEM;    High temperature corrosion;    Oxidation;   

DOI  :  10.1016/j.surfcoat.2018.09.020

来源: Elsevier

【 摘 要 】

Nanolayered CrAIN and CrAIYN/CrAIN (average contents of Al approximate to 25 at.% and Y approximate to 1.6 at. %) coatings are deposited on M2 and 316 steel substrates and heated to 1000 degrees C in air for 2 h to study their oxidation mechanism, the thermal stability and the reactive element (RE) effect of yttrium. CrAIN on M2 develops a Cr2O3/Al2O3 passivation layer that preserves in high degree the fcc-CrAIN structure however iron ions leave the substrate and travel to the surface along the column boundaries. The CrAIYN/CrAIN coatings deposited on steels are not stable at 1000 degrees C, and the initial fcc-CrAIN phase is partially transformed to hcp-Al(O)N and Cr-Fe phases (M2) and Cr2N and Al2O3 (316). The addition of Y changes the predominant scale growth direction. Inward oxygen diffusion becomes dominant but a reduction of the oxide scale thickness as compared to CrAIN is not observed. The advanced microstructural analysis made by transmission electron microscopy combined with electron energy loss spectroscopy determined that yttrium migrates mainly to the oxide scale (forming mixed oxides with substrate elements - V and Mo, either as dispersed particles or segregated at the grain boundaries) in M2, and to the oxide interface and column boundaries (forming Al-Y oxides and YN, respectively) in 316 steel. The benefits of addition of Y in improving the oxidation resistance are discussed comparatively with literature data. The RE effect of yttrium is thus observed to be dependent on the substrate, film architecture and composition.

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