Preparation of Ni-Aluminide Surface Layer Containing Hafnium by Molten-Salt Electrodeposition and Cyclic-Oxidation Resistance

作者：Tabata Kazuki^*; Fujii Hisato; Sato Naka; Hara Motoi

来源：Materials Transactions, 2014, 55(8): 1311-1318.

DOI：10.2320/matertrans.M2014053

• nickel aluminide
• coating
• electrodeposition
• molten salt
• aluminum
• hafnium
• cyclic oxidation

The preparation of a coating consisting of Ni aluminide containing a small amount of Hf was carried out by the electrodeposition of Ni using an aqueous solution and the electrodeposition of Hf and Al using a molten salt. Furthermore, in order to change the depth of the layer containing Hf in the coating, a four-step electrodeposition of Ni, Hf, Ni and Al was carried out, and the times of the first and third Ni electrodepositions were changed. As a result, coatings consisting of Ni aluminide, which contained different depths of the Hf-containig layer, were formed. The cyclic-oxidation resistance of these specimens was evaluated in air at 1423 K. For the specimen with a shallow Hf-containing layer in the coating, the specimen mass reduction due to spallation of the scale was observed, whereas for the specimen with a deep Hfcontaining layer, the specimen mass reduction was only slightly observed and a high-cyclic oxidation resistance was obtained. Among the specimens with a deep Hf-containing layer, the specimen prepared by Hf deposition for 0.6 ks showed the highest cyclic-oxidation resistance. For this specimen, the scale formed on the coating after the oxidation test consisted of Al203. This scale was adhesive, and locally entered the metal substrate.

• 出版日期2014-8