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

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

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    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.
    Original languageEnglish
    Pages (from-to)6035-6048
    Number of pages14
    JournalJournal of the European Ceramic Society
    Volume41
    Issue number12
    Early online date24 Apr 2021
    DOIs
    Publication statusPublished - Sep 2021

    Bibliographical note

    Open access under a Creative Commons license CC-BY

    Funder

    Engineering and Physical Sciences Research Council (EPSRC) (grant number EP/L016206/1 )

    Keywords

    • neutron scattering
    • image analysis
    • porosity
    • suspension thermal spray
    • YSZ

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