Influence of Microstructure on Thermal Properties of Axial Suspension Plasma-Sprayed YSZ Thermal Barrier Coatings

Computational image analysis of Suspension Plasma Sprayed YSZ coatings

“…SPS was developed in order to spray fine-grained powders that cannot be deposited by APS. On one hand, SPS is a very versatile technique (applied amongst others in energy, aerospace, mechanical and petrochemical industries) and provides a variety of coating microstructures [1][2][3]. However, on the other hand, the final coating's properties are highly dependent on the deposition parameters.…”

“…Nevertheless, the great attention has to be paid to this technique [1,2,5]. The total coatings porosity (including both nano-and micropores) is of significant meaning: it affects the wide range of coating properties, such as: elastic modulus, thermal conductivity, dielectric behaviour and many others [3,5,15,17,22].…”

Influence of Isothermal Heat Treatment on Porosity and Crystallite Size in Axial Suspension Plasma Sprayed Thermal Barrier Coatings for Gas Turbine Applications

“…Suspension plasma spraying (SPS) is a relatively more recent technique [13][14][15] that allows depositing porous as well as columnar structured TBCs, which can provide both strain tolerance and lower thermal conductivity and, hence, bear promise for providing enhanced lifetime as well as better thermal insulation [16][17][18][19][20]. SPS not only allows incorporation of higher porosity but also with widely varying pore size ranging from few nanometers to few micrometers [16,20,21].…”

“…SPS not only allows incorporation of higher porosity but also with widely varying pore size ranging from few nanometers to few micrometers [16,20,21]. Depositing TBCs with a columnar structure as in case of EB-PVD, but with higher porosity and in a more cost-effective manner, provides particular motivation for studying the SPS technique comprehensively.…”

“…Hence, it is desirable to have a higher porosity in a TBC, while ensuring that it does not lead to premature degradation of the underlying bond coat through ingress of oxidizing/corrosive species. Notwithstanding the above, porosity measurement is a big challenge especially in SPS TBCs due to the presence of pores that span a wide dimensional scale, from nano-sized fine pores to large micron sized inter-columnar spaces [16,20,21]. Several techniques have been reported in literature to analyze porosity in TBCs [20,21], and the most commonly used are mercury infiltration porosimetry [20,24], image analysis [11,20] and water impregnation [17,25].…”