Microstructure and phase stability of suspension high velocity oxy-fuel sprayed yttria stabilised zirconia coatings from aqueous and ethanol based suspensions

Bai, Mingwen; Maher, Harry; Pala, Zdenek; Hussain, Tanvir

Abstract

Two commercial 7-8 wt.% Yttria Stabilised Zirconia (YSZ) suspensions were sprayed by Suspension High Velocity Oxy Fuel (SHVOF) thermal spraying for advanced high temperature coatings. Heat treatments of the free-standing coatings were conducted at 800 °C and 1000 °C for 72 h. The SHVOF coatings using two liquid carriers: water and ethanol, behaved differently in terms of micro-structure and phase stability. The ethanol coatings retained a fully tetragonal composition after heat treatments; while the aqueous coatings, however, underwent the undesirable tetragonal to monoclinic phase transformation at 1000 °C, which is lower than previously reported temperatures (>1200 °C) in thermal sprayed YSZ coatings. The heat treatments not only resulted in densification of both coatings, but also caused excessive crystallite growth in aqueous coatings promoting the undesirable phase transformation. On the contrary, the ethanol suspension improved the phase stability by favouring the homogenization of yttrium during spraying.

Citation

Bai, M., Maher, H., Pala, Z., & Hussain, T. (in press). Microstructure and phase stability of suspension high velocity oxy-fuel sprayed yttria stabilised zirconia coatings from aqueous and ethanol based suspensions. Journal of the European Ceramic Society, 38(4), https://doi.org/10.1016/j.jeurceramsoc.2017.10.026

• Journal Article Type: Article
• Acceptance Date: Oct 14, 2017
• Online Publication Date: Oct 16, 2017
• Deposit Date: Oct 18, 2017
• Publicly Available Date: Oct 18, 2017
• Journal: Journal of the European Ceramic Society
• Print ISSN: 0955-2219
• Electronic ISSN: 1873-619X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 38
• Issue: 4
• DOI: https://doi.org/10.1016/j.jeurceramsoc.2017.10.026
• Keywords: Suspension high velocity oxy fuel (SHVOF); Yttria-stabilized zirconia (YSZ); Suspension medium; Microstructure; Phase stability
• Public URL: https://nottingham-repository.worktribe.com/output/887993
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S0955221917307045
• Contract Date: Oct 18, 2017