The Influence of Heat Treatments on the Porosity of Suspension Plasma-Sprayed Yttria-Stabilized Zirconia Coatings
Journal article, 2018

Suspension plasma-sprayed coatings are produced using fine-grained feedstock. This allows to control the porosity and to achieve low thermal conductivity which makes the coatings attractive as topcoats in thermal barrier coatings (TBCs). Used in gas turbine applications, TBCs are exposed to high temperature exhaust gases which lead to microstructure alterations. In order to obtain coatings with optimized thermomechanical properties, microstructure alterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBC topcoats consisting of 4 mol.% yttria-stabilized zirconia were heat-treated in air at 1150 °C and thereafter the coating porosity was investigated using image analysis (IA) and nuclear magnetic resonance (NMR) cryoporometry. Both IA and NMR cryoporometry showed that the porosity changed as a result of the heat treatment for all investigated coatings. In fact, both techniques showed that the fine porosity decreased as a result of the heat treatment, while IA also showed an increase in the coarse porosity. When studying the coatings using scanning electron microscopy, it was noticed that finer pores and cracks disappeared and larger pores grew slightly and achieved a more distinct shape as the material seemed to become more compact.

porosity

thermal barrier coatings (TBCs)

heat treatment

image analysis (IA)

nuclear magnetic resonance (NMR) cryoporometry

suspension spraying

axial injection

Author

Johanna Ekberg

Chalmers, Industrial and Materials Science, Materials and manufacture

Ashish Ganvir

University West

Uta Klement

Chalmers, Industrial and Materials Science, Materials and manufacture

Simone Creci

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Lars Nordstierna

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Lars Nordstierna Group

Journal of Thermal Spray Technology

1059-9630 (ISSN) 1544-1016 (eISSN)

Vol. 27 3 391-401

Driving Forces

Sustainable development

Subject Categories

Materials Engineering

Ceramics

Areas of Advance

Materials Science

DOI

10.1007/s11666-017-0682-y

More information

Latest update

9/5/2018 6