Oxidation behaviour of electron beam physical vapour deposition β-NiAlHf coatings at 1100℃ in dry and humid atmospheres
来源期刊：Rare Metals2016年第7期
论文作者：Kai Yan Hong-Bo Guo Hui Peng Sheng-Kai Gong
文章页码：513 - 519
摘 要：NiAl intermetallic compounds attract increasing attention for high-temperature applications due to their combination of excellent properties, especially as metallic protective coatings on superalloys or as bond coats in thermal barrier coatings（TBCs）. Oxidation behaviour of the β-NiAlHf coatings prepared by electron beam physical vapour deposition（EB-PVD） was investigated at 1100 ℃ for short time and 100 h in 20 % O2+Ar and 15% H2O + Ar, respectively. The results of mass changes reveal that the addition of minor reactive element Hf significantly improves the cyclic oxidation resistance of the β-NiAl coatings in both dry and humid atmospheres. During the initial oxidation stage, water vapour retards the phase transformation from θ-Al2O3 to α-Al2O3. Moreover, compared with the case in dry atmosphere, water vapour significantly reduces the surface roughness of the oxide scales formed on EB-PVD β-NiAlHf coatings after 100 h cyclic oxidation, which corresponds with the difference of surface morphologies of the oxide scales.
Kai Yan1，Hong-Bo Guo1,2，Hui Peng1,2，Sheng-Kai Gong1,2
1. School of Materials Science and Engineering,Beihang University2. Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology,Beihang University
摘 要：NiAl intermetallic compounds attract increasing attention for high-temperature applications due to their combination of excellent properties, especially as metallic protective coatings on superalloys or as bond coats in thermal barrier coatings（TBCs）. Oxidation behaviour of the β-NiAlHf coatings prepared by electron beam physical vapour deposition（EB-PVD） was investigated at 1100 ℃ for short time and 100 h in 20 % O2+Ar and 15% H2O + Ar, respectively. The results of mass changes reveal that the addition of minor reactive element Hf significantly improves the cyclic oxidation resistance of the β-NiAl coatings in both dry and humid atmospheres. During the initial oxidation stage, water vapour retards the phase transformation from θ-Al2O3 to α-Al2O3. Moreover, compared with the case in dry atmosphere, water vapour significantly reduces the surface roughness of the oxide scales formed on EB-PVD β-NiAlHf coatings after 100 h cyclic oxidation, which corresponds with the difference of surface morphologies of the oxide scales.
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