Abstract
In this study, the mechanical resistance and the thermal insulation potential of novel thermal barrier coatings (TBCs) made of a foam of hollow alumina particles are assessed through scratch testing, micro-indentation and thermal diffusivity measurements using laser-flash. The thermal diffusivity of the foam coatings ranges between 0.6 × 10−7 and 5 × 10−7 m2·s−1 and is thus comparable with the thermal insulation potential of the standard plasma-sprayed (PS) and electron beam–physical vapour-deposited (EB-PVD) TBCs made of yttria-stabilised zirconia (YSZ). The coatings annealed in more oxidative atmospheres exhibit greater mechanical resistance due to the thickening of the alumina shells and the increased sintering of the foam. However, when the oxidation is poorly tailored, the adhesion of the foam to the substrate decreases due to the presence of unwanted oxide that grows at the substrate/coating interface.
Highlights
The current demand for greater efficiency and a reduction in fuel consumption and greenhouse gas emissions requires higher-temperature operating conditions in gas turbines, including in the low-pressure turbine (LPT) section [1]
The mechanical resistance and the thermal insulation potential of novel thermal barrier coatings made of a foam of hollow alumina particles were assessed through scratch testing, micro-indentation and thermal diffusivity measurements
All the coatings showed great thermal insulation properties on a par with the ones of the state-of-the-art yttria-stabilised zirconia (YSZ) thermal barrier coatings (TBCs) made by plasma spraying or electron beam–physical vapour-deposited (EB-PVD)
Summary
The current demand for greater efficiency and a reduction in fuel consumption and greenhouse gas emissions requires higher-temperature operating conditions in gas turbines, including in the low-pressure turbine (LPT) section [1]. The formation of a complete thermal barrier coating using the slurry technique appears to be attractive for the materials of the LPT section due to its relatively low cost and ease of application [2]. This technology often uses an aqueous slurry that contains Al microparticles, which forms a foam of hollow alumina microspheres on top of an aluminide coating after proper annealing [3,4].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
