Spain. Researchers from the Institute of Ceramics and Glass in Madrid have developed sol-gel coatings obtained by electrophoretic deposition (EPD) on metals.
The sol-gel process is a method of great interest for the production of vitreous films on metals, which act as a protective barrier against oxidation and increase their resistance to corrosion. Inorganic and hybrid coatings of different compositions have been obtained on different metals using techniques such as immersion, centrifugation and spraying. Although these methods provide coatings with good properties, the thicknesses obtained are low (less than 2 mm), which limits their application possibilities.
Electrophoretic deposition (EPD) is emerging as a technique of great versatility for obtaining homogeneous coatings of greater thickness. The objective of this research was the preparation of coatings on metal by EPD from hybrid solutions of SiO2 (TEOS, MTES) and colloidal suspensions of SiO2 in which the hybrid solutions themselves act as a dispersion medium.
Both solutions and suspensions have been studied using viscosity, density and conductivity measurements. Likewise, the physical parameters associated with EPD, such as deposition time and current density, have been studied, taking into account the additional effect of layer formation by immersion during extraction. The coatings have been characterized by profilometry and optical microscopy, comparing the layers deposited by immersion and those obtained by EPD.
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