Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying

Effect of particle size distribution of suspension feedstock on the microstructure and mechanical properties of suspension plasma spraying YSZ coatings

“…Figure 2 shows the cross-sectional SEM images of the as-sprayed coatings obtained from Yn, Ys and Ysn feedstocks at the three spraying distances tested (in the case of the Yn sample the longest spraying distance was not realised). As reported elsewhere all the micrographs reveal two-zones microstructure, named as (I) molten melted and (II) sintered grains areas [11,15], which are displayed on the micrographs. For the sake of distinguishing porosity is also marked P in the micrographs.…”

“…This is the usual phase in as-sprayed coatings when the yttria proportion is 3 mol% [11]. However small peaks of monoclinic phase were detected in those coatings obtained from feedstocks containing nanoparticles due to the presence of [11].…”

“…Average values of hardness and elastic modulus were then determined for a depth range from 100 to 200 nm. More details of this procedure can be found in previous research [10,11]. Figure 1 shows the evolution of zeta potential of nano-and submicron-sized YSZ powders without dispersant and with different contents of PAA.…”

“…However, the amount of papers dealing with the use of nanoindentation method to characterise SPS layers is still very scarce [10]. In a recent work by some of the authors [11], it was proved that hardness and elastic modulus of SPS YSZ coatings could be estimated by this technique.…”

Mechanical Properties of Double-Layer and Graded Composite Coatings of YSZ Obtained by Atmospheric Plasma Spraying

“…Nanoindentation technique has been succesfully used for characterisation of mechanical properties of plasma spray coatings because this technique allows to easily distinguish the melted and partially melted areas in the coatings and therefore to correlate these areas with mechanical properties by determining elastic modulus and/or hardness of different points throughout the coating cross-section [14,15]. Thus first part of the research previous works have shown that elastic modulus and hardness in titania or YSZ coatings can widely vary on the basis of the amount of partially melted areas present in the coatings while the porosity and sintering degree of these partially melted areas can also play a role [5].…”