Re对NiCrAlY涂层热腐蚀行为的影响

EFFECT OF Re ON THE HOT-CORROSION BEHAVIOR OF A NiCrAlY OVERLAY COATING

通过电弧离子镀制备了NiCrAlYRe和NiCrAlY涂层,经真空热处理后涂层均由γ′-Ni_3Al、γ-Ni、β-NiAl和α-Cr四相构成。在NiCrAlYRe涂层中,Re主要存在于α-Cr相,Re促进了α-Cr相在涂层中的析出,并提高了α-Cr在长期氧化过程中的稳定性,特别在氧化膜/涂层界面上析出了大量富Re的α-Cr。由于富Re的α-Cr同α-Al_2O_3具有极为接近的热膨胀系数,降低了氧化膜中的热应力,提高了NiCrAlY涂层表面抗剥落能力。添加Re明显提高了NiCrAlY涂层在900℃90%Na_2SO_4+10%K_2SO_4介质中的抗热腐蚀性能。

Arc ion plating（AIP） was used to produce NiCrAlY and NiCrAlYRe overlay coatings.After heat treatment in vacuum,both of the coatings consisted ofγ′-Ni_3Al,γ-Ni,β-NiAl andα-Cr.Re in the NiCrAlYRe coating existed inα-Cr and promoted the precipitation and thermal stability ofα-Cr.The existence ofα-Cr in the interface of coating and substrate lowered coefficient of thermal expansion and thus reduced thermal stress in the surface scale,improving adherence of the scale.The addition of Re obviously increased hot corrosion resistance of NiCrAlY in 90%Na_2SO_4＋10 mass%K_2SO_4.