Electrochemical formation of MoSi2 film on Ni-based superalloy

Osamu Takeda, Shigeki Yamanaka, Masayoshi Hoshi, Hongmin Zhu, Yuzuru Sato

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1 Citation (Scopus)

Abstract

The growth of MoSi2 films by the electrochemical siliciding of Mo was investigated and MoSi2 film formation was attempted on a Ni-based superalloy (CMSX-4) via a two-step coating process. An oxidation test of the MoSi2 film was also performed. A thick MoSi2 film was obtained at a temperature below 1073 K. At a relatively high current density of 100 mA · cm-2, the supply of Si to the Mo surface was too fast and pure Si was deposited outward instead of alloying. The growth rate of MoSi2 at 50 mA · cm-2 was 57 μm · h-1, abnormally fast compared to that by normal diffusion. This indicated that Si diffused through the grain boundaries, rather than through grain bodies. A dense and homogeneous MoSi2 film, approximately 100 μm thick, was successfully formed on CMSX-4. The boundaries in MoSi2/Mo and Mo/CMSX-4 were coherent. After oxidation testing, a multilayer comprising SiO2, MoSi2, Mo5Si3, Mo, an intermediate layer, and CMSX-4 was formed. The SiO2 film was significantly thick at 10-30 μm compared to literature values. To obtain a thin SiO2 film, a MoSi2 layer with fewer defects might be required.

Original languageEnglish
Pages (from-to)D978-D984
JournalJournal of the Electrochemical Society
Volume164
Issue number14
DOIs
Publication statusPublished - 2017

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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