Comparing the deposition mechanisms in suspension plasma spray (SPS) and solution precursor plasma spray (SPPS) deposition of yttria-stabilised zirconia (YSZ)

Abstract

Thermal spraying using liquid feedstock has emerged as a promising technology for the deposition of finely structured ceramic coatings. In order to provide a comparative assessment of the deposition mechanisms occurring when spraying suspension or solution feedstock, suspensions of 300 nm-sized ZrO2–4.5 mol.% Y2O3 particles dispersed in water and in ethanol and solutions of zirconium and yttrium salts, corresponding to ZrO2–4.5 mol.% Y2O3 and ZrO2–8 mol.% Y2O3 stoichiometries, were processed by plasma spraying using different parameter settings. In-flight diagnostics of sprayed droplets, together with the morphological, microstructural and phase analysis of individual lamellae collected onto polished substrates, performed by SEM, FIB, AFM and micro-Raman spectroscopy, led to the identification of deposition mechanisms, which were subsequently verified through the characterisation of complete coating layers

Aqueous suspension processing of multicomponent submicronic Y-TZP/Al 2 O 3 /SiC particles for suspension plasma spraying

“…SPS is an emerging thermal spray process in which the powder feedstock is replaced by a suspension feedstock. An important benefit of SPS process is the possibility of spraying very fine, poor flowability powders [3,[19][20][21][22][23]. Moreover, the SPS technique would be very favourable to avoid undesirable oxidation of the sealing material because a lot of the plasma energy is destined to solvent (water) evaporation.…”

“…Moreover, the SPS technique would be very favourable to avoid undesirable oxidation of the sealing material because a lot of the plasma energy is destined to solvent (water) evaporation. However, limiting energy during plasma deposition can compromise coating microstructure and adherence since the particles may not melt as much as required [3,19,21]. For this reason, the optimisation of solid content and stability of SPS feedstock containing SiC particles is necessary to obtain coatings in which the amount of SiC particles can be maximised.…”

A study of the influence of TiO2 addition in Al2O3 coatings sprayed by suspension plasma spray

“…Several reports have demonstrated that nanometric ZrO 2 [17,18], TiO 2 [19][20][21] and Al 2 O 3 [22,23] are successfully deposited by SPS. The SPS coatings obtained using nanopowder feedstock exhibit superior characteristics due to the fact that they present a much lower porosity, leading to a denser structure.…”

Characteristics of selected methods for the synthesis of nanometric zirconium oxide – critical review

“…For example, it may be a magnetron spu ering [13,14], plasma spraying [15][16][17][18][19][20], which consists in creating a plasma of high temperature, to 2000 K, and then delivered thereto, by a carrier gas, the material in the form of a powder that will be deposited. Hass et al [15] concluded that a ceramic coating obtained this way may exhibit less consistency with the substrate and be characterized by higher porosity and non-uniform distribution of the pore volume fraction and shape.…”