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采用Ni和AI颗粒复合电沉积与后续真空退火的方法,分别于600℃和800℃退火温度下制备了两种新型细晶Ni_3Al涂层。与粗晶合金相比,经1000℃氧化20 h后,合金的氧化层发生大面积剥落,而两种涂层的氧化膜粘附性佳,其主要原因为细晶涂层内的大量晶界促进Al向氧化前沿的扩散,从而抑制了氧化膜/基体界面处“Kirkendall”孔洞的形成与长大。同时发现,800℃退火涂层氧化膜结构由外至内分别为NiO/NiAl_2O_4/Al_2O_3,而600℃退火涂层仅生成NiAl_2O_4与Al_2O_3,对该原因进行了探讨。
Two new types of fine-grained Ni 3 Al coatings were prepared at 600 ℃ and annealing temperature of 800 ℃ respectively by Ni-AI particles composite electrodeposition and subsequent vacuum annealing. Compared with the coarse-grained alloy, the oxide layer of the alloy peeled off extensively after being oxidized at 1000 ℃ for 20 h, and the adhesion of the two coatings was good, mainly due to the large number of grain boundaries Promote the diffusion of Al to the oxidation front, thereby inhibiting the formation and growth of the “Kirkendall” hole at the oxide film / substrate interface. It is also found that the structure of the oxide film annealed at 800 ℃ is NiO / NiAl_2O_4 / Al_2O_3 from the outside to the inside, while the annealing coating at 600 ℃ only produces NiAl_2O_4 and Al_2O_3.