Michihisa Fukumoto, Takeru Rikiishi, Kiyohide Sugita and Motoi Hara
Department of Materials Science and Engineering, Graduate School of Engineering and Resource Science, Akita University, Akita 010-8502
The formation of coating layer consisting of a Ni aluminide containing Hf on a Ni substrate was tried by the electrodeposition of Hf and Al. The cyclic oxidation resistance for the Ni covered with the coating was then evaluated. Hf and Al were deposited by molten salt electrolysis. For the sample treated with the Hf deposition, followed by the Al deposition at 1023 K, the Ni2Al3 layer and Al3Hf layer were formed in that order from the substrate. On the other hand, for the sample treated with the Hf deposition, followed by the Al deposition at 1173 K, the NiAl layer containing Hf was formed. Further, when electrodeposition time of Hf was changed, the amount of Hf in NiAl layer was changed. The cyclic oxidation test showed that for the untreated sample, the sample with Al depositions and the sample coated with Ni2Al3/Al3Hf layer, the mass reduction due to exfoliation of a scale took place. However, for the sample coated NiAl layer containing of Hf, the mass reduction was not observed. For this sample after the cyclic oxidation test, a scale consisting of α-Al2O3 adhering to the substrate was formed. Consequently, it was found that a cyclic oxidation resistance of the sample was improved by coating with the NiAl layer containing Hf. [doi:10.2320/jinstmet.JB201201]
electrodeposition, molten salt, hafnium, aluminum, cyclic oxidation, nickel aluminide, coating
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