Evolution of Porosity in Suspension Thermal Sprayed YSZ Thermal Barrier Coatings through Neutron Scattering and Image Analysis Techniques

Tejero-Martin, Daniel; Bai, Mingwen; Mata, Jitendra; Hussain, Tanvir

Abstract

Porosity is a key parameter on thermal barrier coatings, directly influencing thermal conductivity and strain tolerance. Suspension high velocity oxy-fuel (SHVOF) thermal spraying enables the use of sub-micron particles, increasing control over porosity and introducing nano-sized pores. Neutron scattering is capable of studying porosity with radii between 1 nm and 10 µm, thanks to the combination of small-angle and ultra-small-angle neutron scattering. Image analysis allows for the study of porosity with radii above ~100 nm. For the first time in SHVOF 8YSZ, pore size distribution, total porosity and pore morphology were studied to determine the effects of heat treatment. X-ray diffraction and micro-hardness measurements were performed to study the phase transformation, and its effects on the mechanical properties. The results show an abundant presence of nano-pores in the as-sprayed coatings, which are eliminated after heat treatment at 1100 °C; a transition from inter-splat lamellar to globular pores and the appearance of micro-cracks along with the accumulation of micro-strains associated with the phase transformation at 1200 °C.

• Journal Article Type: Article
• Acceptance Date: Apr 9, 2021
• Online Publication Date: Apr 24, 2021
• Publication Date: Sep 1, 2021
• Deposit Date: Apr 21, 2021
• Publicly Available Date: Apr 24, 2021
• Journal: Journal of the European Ceramic Society
• Print ISSN: 0955-2219
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 41
• Issue: 12
• Pages: 6035-6048
• DOI: https://doi.org/10.1016/j.jeurceramsoc.2021.04.020
• Keywords: neutron scattering; image analysis; porosity; suspension thermal spray; YSZ
• Public URL: https://nottingham-repository.worktribe.com/output/5486500
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0955221921002739