Characterization of sol–gel coatings deposited on a mechanically treated stainless steel by using a simple non-destructive electrical method

Abstract

Coating solution of yttria-doped zirconia was prepared by using the solgel method and deposited on AISI 304 stainless steel substrates using dip-coating technique. The influence of the mechanical modification of stainless steel substrates and withdrawal rate on the coating quality has been studied. Herein, a novel method based on measuring the electrical capacitance of such coatings is developed in order to assess the coating quality. The method was performed on sanded and polished samples coated at various withdrawal rates, obtaining the greater thickness uniformity for the coatings deposited on polished specimens coated at a withdrawal rate of 25 mm·min ¹1. The results obtained by the proposed method are well in agreement with those found by both optical and electron microscopies. Therefore, such a method seems to be of great interest because of its simplicity and low cost as compared to other well-established techniques, and its results may be a great support for them.

Electrochemical Impedance Analysis for Corrosion Rate Monitoring of Sol–Gel Protective Coatings in Contact with Nitrate Molten Salts for CSP Applications

“…As expected, and in line with the previously reported study [ 48 ], coated samples showed good uniformity given the high homogeneity in colour, which was a methodology proposed by Morrow et al [ 49 ].…”

Corrosion resistance of protective coatings against molten nitrate salts for thermal energy storage and their environmental impact in CSP technology

“…The 3 mol% yttria-doped zirconia sol-gel solution was prepared in accordance with a previously reported procedure (Encinas-Sánchez et al, 2017;Encinas-Sánchez et al, 2016).…”

“…3). This non-uniformity in thickness may be attributed to the surface preparation (Encinas-Sánchez et al, 2016;Encinas-Sánchez et al, 2015). Furthermore, a diffusion zone was observed, this being a consequence of the thermal treatment to which coatings are subjected during their application.…”

Zirconia-based coatings for the protection of ferritic-martensitic steels in a molten salt environment for CSP technology

“…This heat treatment promotes the densification of the film without unsuitable degradations. The surface preparation, withdrawal rate and heat treatment were selected on the basis of previously published studies [30,31], owing to the good thickness uniformity they provide.…”