Advances in the control of electrophoretic process parameters to tune the ytterbium disilicate coatings microstructure

Abstract

Suspensions of ytterbium disilicate in isopropanol were prepared using iodine dispersant. Their zeta potential, electrical conductivity, and pH dependence with iodine concentration is detailed. Electrophoretic deposition was performed on silicon substrates at various voltages (100-200 V) and times (until 10 minutes) and the growth dynamic was investigated. It was observed that the deposited mass reaches a maximum value for [I 2 ] = 0.2 g/L, and the coating microstructure becomes porous at higher iodine concentrations. Current density and voltage measurements allowed to correlate this behavior to the increase of free protons concentration in the suspension. In these conditions, it was proved that porosity increases with the increase in applied voltage, and a compaction occurs as the deposition time increases. This has been related to the coating resistance increase and subsequent decrease in effective voltage in the suspension. The denser coatings (20% of porosity) were obtained in the case of suspension without iodine, at the minimum applied voltage and for the longest deposition times.

Review of processing and design methodologies of environmental barrier coatings for next generation gas turbine applications

“…Although EPD has not been widely used for the processing of EBCs, preliminary works on the processing of rare-earth silicate EBC via EPD were undertaken by Prioux et al [55] and Yilmaz et al [56]. Prioux et al [55] studied the effect of dispersant concentration (iodine), applied voltage, and deposition time on microstructural characteristics of Yb 2-Si 2 O 7 green coatings such as thickness, density, and homogeneity. They reported that increasing dispersant concentration, up to 2 g/L, increased the deposition rates, but a further increase resulted in a reduction in the relative coating density.…”

Solvent‐Free Synthesis of PMMA Particles using Tandem Acoustic Emulsification

“…Ceramic particles find applications in protective coatings. These include so‐called thermal barrier coatings or environmental barrier coatings for engine applications, mostly in the aeronautics industry [7–9] . For these applications, particles size range is 0.02–2 μm.…”

“…These include so-called thermal barrier coatings or environmental barrier coatings for engine applications, mostly in the aeronautics industry. [7][8][9] For these applications, particles size range is 0.02-2 μm. In these fields, particles are deposited through electrophoretic deposition (EPD), allowing a quite dense and thin deposit to be obtained compared with more conventional ceramic deposition processes, for instance thermal spray deposition.…”

Integrated Regeneration Method for Used Mineral Motor Oils

“…Taking into account the short life of cordieritemullite refractory materials, associated with destructive processes caused by aggressive factors in their surface layers [1], it is advisable to protect the surface of refractories by coating. The use of known coating compositions for the protection of cordierite-mullite refractories is unacceptable due to the significant difference between the thermal coefficients of linear expansion (TCLE) of these coatings and the substrate ((6-10)•10 -6 K -1 ) [2][3][4][5][6]. The coating for the protection of cordierite-mullite refractories should have a composition that will provide a TCLE value close to that of cordierite ceramics, i.e., within ((2.0-3.5)•10 -6 K -1 ).…”