Thick Sol-Gel Coatings Produced by Electrophoretic Deposition

Abstract

Thick, glass‐like coatings that are crack‐free, homogeneous, and transparent are obtained by electrophoretic deposition (EPD) from particulate hybrid sols prepared under basic catalysis (see Figure for an SEM image at the cross section of a coating). The fast EPD kinetics inhibits substrate corrosion. Potentiodynamic tests confirm the dielectric nature of the coating and its suitability for protecting metals.

One-pot manufacture of nanoparticle-based films in aqueous media via an electric field-driven assembly process

“…6 The one-pot process approach, regarded as synthesis, stabilization and EPD of nano-entities, has been proven for nonpolar solvents 17 and for a hybrid sol-gel synthesis route. 18,19 In both cases, solvents diminished the effects of water electrolysis during the deposition. The mechanism that we propose now is to process dense and complete films by electrophoretic deposition using well dispersed as-synthesized nanoparticles hydrothermally synthesized at mild conditions, that is at temperatures lower than 180 °C.…”

TiO2/Eu3+ Thin Films with High Photoluminescence Emission Prepared by Electrophoretic Deposition from Nanoparticulate Sols

“…These nanopowders can be used for the preparation of the thin films by different deposition techniques such as dipping,17,18 low‐pressure hot target magnetron sputtering,23 or pulsed laser deposition 24. Previous works25 dealing with the preparation of glass‐like coatings on metallic substrates have unequivocally demonstrated that the use of EPD enabled the preparation of coatings with a greater thickness and increased density and uniformity than those obtained by simply dipping. Consequently, those coatings presented fewer defects (in terms of thickness and homogeneity) and exhibited better properties, with an increase of the corrosion resistance by nearly four orders of magnitude.…”

Forming of Ceramic Laminates Comprising Thin Layers of a Few Particles

“…Hence, fabrication of laminated materials with very thin layers is in focus and requires the development of simple and innovative processing strategies able to produce defect‐free, uniform layers integrated in complex structures. Among the processing techniques developed to fabricate layered ceramics from precursors or from powder processing techniques 23,24 dip coating has been extensively used in the sol–gel technology to produce thin functional coatings onto ceramic, glass, and metallic substrates 25,26 . The consolidation of a coating layer by dipping is achieved by the deposition and evaporation of the liquid, although it can also be assisted by an external force like filtration or electrophoretic deposition 26–28 .…”

“…Among the processing techniques developed to fabricate layered ceramics from precursors or from powder processing techniques 23,24 dip coating has been extensively used in the sol–gel technology to produce thin functional coatings onto ceramic, glass, and metallic substrates 25,26 . The consolidation of a coating layer by dipping is achieved by the deposition and evaporation of the liquid, although it can also be assisted by an external force like filtration or electrophoretic deposition 26–28 . The thickness of the films fabricated by dip coating can vary from nanometers to a few tens of micrometers depending on substrate parameters (wettability, roughness, and porosity), sol/suspension parameters (viscosity, solid content, binders content, and surface tension), and specific processing parameters (withdrawal rate, soaking time, temperature, and humidity) 29–31 .…”