An amorphous SiAlN barrier coating against NaCl attack in humid air at elevated temperature

Zhaohe Gao, Justyna Kulczyk-Malecka, Han Liu, Peter Kelly, Ping Xiao, Yu-Lung Chiu

Research output: Contribution to journalArticlepeer-review

Abstract

Amorphous magnetron sputtered SiAlN films have been designed to prevent NaCl attack of Ti alloy substrates in high temperature humid air environments. Uncoated Ti alloys suffer severe degradation after exposure to NaCl deposits in humid air at 700 °C for 100 h, whereas SiAlN coating forms protective scale mainly consisting of sodium silicate in identical conditions. Amorphous sodium silicate exhibits fast Na+ diffusion rate and extremely slow O2- diffusion rate, but degradation of SiAlN takes place in presence of both O2- and Na+ species. Sodium silicate scale provides good protection for SiAlN due to slow diffusion of O2- through sodium silicate.
Original languageEnglish
Article number110321
Number of pages12
JournalCorrosion Science
Volume203
Early online date21 Apr 2022
DOIs
Publication statusE-pub ahead of print - 21 Apr 2022

Keywords

  • Amorphous SiAlN
  • NaCl attack
  • Sodium Silicate
  • Degradation

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